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stone-game-v
Beats 60.00%of users with JavaScript
beats-6000of-users-with-javascript-by-ss-hvj9
\n# Code\n\nvar stoneGameV = function(stoneValue) {\n let n = stoneValue.length;\n const pre = new Array(n + 1).fill(0);\n for (let i = 1; i <= n; i++) {\n
SSDeepakReddy
NORMAL
2023-10-14T05:32:22.145488+00:00
2023-10-14T05:32:22.145514+00:00
56
false
\n# Code\n```\nvar stoneGameV = function(stoneValue) {\n let n = stoneValue.length;\n const pre = new Array(n + 1).fill(0);\n for (let i = 1; i <= n; i++) {\n pre[i] = pre[i - 1] + stoneValue[i - 1];\n }\n const dp = [...Array(n).fill(null)].map((_) => new Array(n).fill(0));\n for (let l = 1; l < n; l++) {\n for (let i = 0; i < n - l; i++) {\n let j = i + l,\n res = 0;\n for (let k = i; k < j; k++) {\n let left = pre[k + 1] - pre[i],\n right = pre[j + 1] - pre[k + 1];\n if (left < right) {\n res = Math.max(res, left + dp[i][k]);\n } else if (left > right) {\n res = Math.max(res, right + dp[k + 1][j]);\n } else {\n res = Math.max(res, left + dp[i][k]);\n res = Math.max(res, right + dp[k + 1][j]);\n }\n }\n dp[i][j] = res;\n }\n }\n return dp[0][n - 1];\n};\n```
1
0
['JavaScript']
0
stone-game-v
Basic Java Solution(Commented)
basic-java-solutioncommented-by-karthik_-r5nd
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time
Karthik_1512
NORMAL
2023-09-16T17:16:11.484621+00:00
2023-09-16T17:16:11.484644+00:00
140
false
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution {\n public int findSum(int[] stoneValue)\n {\n int sum=0;\n for(int n:stoneValue) sum+=n;\n return sum; // returns the sum of the stoneValue Array.\n }\n public int findMin(int[] stoneValue,int start,int end,int preSum,int sum,int[][] dp)\n {\n if(start==end) return 0; // returns 0 whenever the length of the array equals 1.\n\n if(dp[start][end]!=-1) return dp[start][end]; // returns the stored value of the sub problem when the specific values of start and end already solved before.\n\n int ans=Integer.MIN_VALUE; // Initializing the required maximum score of alice with the minimum possible integer.\n\n for(int i=start;i<end;i++) // Iterating a for loop from the starting index to the ending index to check with all the possible partitions.\n {\n preSum=preSum+stoneValue[i]; //Increment the preSum with value of stoneValue at current index where we are going to make partition.\n\n if(preSum < sum-preSum)\n {\n ans=Math.max(ans,preSum+findMin(stoneValue,start,i,0,preSum,dp)); \n //if the preSum(the sum of the array from start index to current index) is less than the remaining part of the array,\n //Then Bob throws away the right array i.e the array with the largest sum,\n //Alice score is increased by preSum(sum of the left array) and parameters of the left array are sent to the recursion.\n }\n else if(preSum>sum-preSum)\n {\n ans=Math.max(ans,sum-preSum+findMin(stoneValue,i+1,end,0,sum-preSum,dp));\n //if the preSum(the sum of the array from start index to current index) is more than the remaining part of the array,\n //Then Bob throws away the left array i.e the array with the largest sum,\n //Alice score is increased by sum-preSum(sum of the right array) and parameters of the right array are sent to the recursion.\n }\n else{\n ans=Math.max(ans,Math.max(preSum+findMin(stoneValue,start,i,0,preSum,dp),sum-preSum+findMin(stoneValue,i+1,end,0,sum-preSum,dp)));\n // if the preSum(the sum of left array) and sum-preSum(the sum of the right array) are equal,\n // Then, Bob gives Alice a chance to remove either the left array or the right array,\n // So alice has a chance to get maximum score from either of the arrays,\n // So Alice take the the Max value from both the recursions(recursion calls of both left array and right array).\n }\n }\n return dp[start][end]=ans; // store the value of the partition for specific start and end values in the dp array.\n }\n public int stoneGameV(int[] stoneValue) {\n int sum = findSum(stoneValue); // To find Sum of the stoneValue array.\n\n int[][] dp = new int[stoneValue.length][stoneValue.length]; // A 2D array for memorization.\n\n for(int i=0;i<stoneValue.length;i++)\n {\n Arrays.fill(dp[i],-1); // Initializing all the values of the 2D array dp with -1.\n }\n return findMin(stoneValue,0,stoneValue.length-1,0,sum,dp); // function to find Maximum score of alice.\n }\n}\n```\n**Thank You : )**
1
0
['Dynamic Programming', 'Recursion', 'Memoization', 'Prefix Sum', 'Java']
1
stone-game-v
Python O(n^2) DP Solution, faster than 100%(1399ms)
python-on2-dp-solution-faster-than-10013-cf6a
\n\'\'\'\nSuppose we know the k\' for stones[i..j], what do we know about k\' for stones[i..j+1]? It is either the same or it got shifted a few places to the ri
hemantdhamija
NORMAL
2022-10-16T07:53:06.184473+00:00
2022-10-16T07:53:06.184514+00:00
846
false
```\n\'\'\'\nSuppose we know the k\' for stones[i..j], what do we know about k\' for stones[i..j+1]? It is either the same or it got shifted a few places to the right.\nAnd so if we calculate dp values in the order: dp[i][i], dp[i][i+1], dp[i][i+2], ..., dp[i][j], we can essentially keep track of k\' as we go within that same linear time bound.\n\nUsing this idea, we implement the final solution. Couple of pointers about my code:\n\n1) mid: represents k\' or first index such that left half >= right half\n2) with i < j, max[i][j] represents left[i][j] of previous solution i.e. max(dp[i][i], dp[i][i+1], dp[i][i+2] .. dp[i][j]) and max[j][i] represents right[i][j] of previous solution i.e. max(dp[i][j], dp[i+1][j], dp[i+2][j] .. dp[j][j]). We could have used two different arrays left and right just like previous solution but this trick saves space.\n3) I am traversing in the order: dp[j][j], dp[j-1,j], dp[j-2, j], .., dp[i][j] instead of the above mentioned order but the idea remains same.\n\'\'\'\n\nclass Solution:\n def stoneGameV(self, stoneValue: List[int]) -> int:\n sz = len(stoneValue)\n dp, maxScore = [[0] * sz for _ in range(sz)], [[0] * sz for _ in range(sz)]\n for i in range(sz):\n maxScore[i][i] = stoneValue[i]\n for j in range(1, sz):\n mid, sm, rightHalf = j, stoneValue[j], 0\n for i in range(j - 1, -1, -1):\n sm += stoneValue[i]\n while (rightHalf + stoneValue[mid]) * 2 <= sm:\n rightHalf += stoneValue[mid]\n mid -= 1\n dp[i][j] = maxScore[i][mid] if rightHalf * 2 == sm else (0 if mid == i else maxScore[i][mid - 1]);\n dp[i][j] = max(dp[i][j], 0 if mid == j else maxScore[j][mid + 1])\n maxScore[i][j] = max(maxScore[i][j - 1], dp[i][j] + sm);\n maxScore[j][i] = max(maxScore[j][i + 1], dp[i][j] + sm);\n return dp[0][sz - 1]\n```
1
1
['Dynamic Programming', 'Memoization', 'Python', 'Python3']
0
stone-game-v
Simple Partition DP | Recursive | Memoization
simple-partition-dp-recursive-memoizatio-2vj5
We need to try out all possible partition for every subproblem hence partition dp.\n\tBase Case: When there is only one element left in subarray (i.e i == j) we
lrrajput2001
NORMAL
2022-09-08T13:05:06.769420+00:00
2022-09-08T13:05:50.037944+00:00
395
false
We need to try out all possible partition for every subproblem hence **partition dp**.\n\t**Base Case:** When there is only one element left in subarray (i.e i == j) we return 0 because alice cannot score anything from that.\n```\nint f(int i,int j,vector<int> &stoneValue,vector<vector<int>> &dp){\n if(i == j) return 0;\n if(dp[i][j] != -1) return dp[i][j];\n int totSum = 0;\n for(int k = i ; k <= j ; k++) totSum += stoneValue[k];\n int leftSum = 0;\n int res = INT_MIN;\n for(int k = i ; k < j ; k++){\n leftSum += stoneValue[k];\n int rightSum = totSum - leftSum;\n if(leftSum == rightSum){\n int dropLeft = rightSum + f(k+1,j,stoneValue,dp);\n int dropRight = leftSum + f(i,k,stoneValue,dp);\n res = max(res,max(dropLeft,dropRight));\n }\n else if(leftSum < rightSum) res = max(res,leftSum + f(i,k,stoneValue,dp));\n else res = max(res,rightSum + f(k+1,j,stoneValue,dp));\n }\n return dp[i][j] = res;\n }\n int stoneGameV(vector<int>& stoneValue) {\n int n = stoneValue.size();\n vector<vector<int>> dp(n,vector<int> (n,-1));\n return f(0,n-1,stoneValue,dp);\n }\n```
1
0
['Dynamic Programming', 'Recursion', 'Memoization', 'C']
0
stone-game-v
c++
c-by-rony_the_loser-iqt7
(```) class Solution {\npublic:\n \n int dp[501][501];\n \n int help(vector& v, int start, int end)\n {\n if(start > end) \n {
Algo_wizard2020
NORMAL
2022-08-27T18:38:41.015707+00:00
2022-08-27T18:38:41.015740+00:00
37
false
(```) class Solution {\npublic:\n \n int dp[501][501];\n \n int help(vector<int>& v, int start, int end)\n {\n if(start > end) \n {\n return 0;\n }\n \n int sum = 0, left_sum = 0, right_sum =0,ans = 0;\n \n if(dp[start][end] != -1)\n {\n return dp[start][end];\n }\n \n for(int i=start; i<=end; i++)\n {\n sum += v[i];\n }\n \n for(int j=start; j<=end; j++)\n {\n left_sum += v[j];\n \n right_sum = sum - left_sum;\n \n if(left_sum < right_sum)\n {\n ans = max(ans,left_sum + help(v,start,j));\n }\n else if(left_sum > right_sum)\n {\n ans = max(ans, right_sum + help(v,j+1,end));\n }\n else\n {\n ans = max(ans,left_sum + help(v,start,j));\n ans = max(ans, right_sum + help(v,j+1,end));\n \n }\n \n }\n \n return dp[start][end] = ans;\n }\n \n int stoneGameV(vector<int>& stoneValue) \n {\n \n memset(dp,-1,sizeof(dp));\n \n return help(stoneValue, 0, stoneValue.size()-1);\n \n \n }\n};
1
0
[]
0
stone-game-v
[C++] || DP || Check Every possible Partition
c-dp-check-every-possible-partition-by-r-gmm6
\nclass Solution {\npublic:\n int dp[501][501] ;\n int solve(vector<int>&nums , int s , int e){\n if(s == e) return 0 ; \n if(dp[s][e] != -1
rahul921
NORMAL
2022-07-13T13:27:01.106070+00:00
2022-07-13T13:36:17.826639+00:00
181
false
```\nclass Solution {\npublic:\n int dp[501][501] ;\n int solve(vector<int>&nums , int s , int e){\n if(s == e) return 0 ; \n if(dp[s][e] != -1) return dp[s][e] ;\n \n int sum = 0 , left = 0 , right = 0 ;\n for(int i = s ; i <= e ; ++i) sum += nums[i] ;\n \n int op1 = 0 , op2 = 0 ;\n for(int i = s ; i < e ; ++i ){\n left += nums[i] , right = sum - left ;\n if(left <= right) op1 = max(op1,left + solve(nums,s,i)) ;\n if(left >= right) op2 = max(op2,right + solve(nums,i+1,e)) ;\n }\n \n return dp[s][e] = max(op1,op2) ;\n }\n int stoneGameV(vector<int>& nums) {\n memset(dp,-1,sizeof(dp)) ;\n return solve(nums,0,nums.size() - 1) ;\n }\n};\n```
1
0
['C']
0
stone-game-v
Worst case time complexity when using recursion without DP
worst-case-time-complexity-when-using-re-o0nl
I was able to solve this problem using DP in O(n^2) time + top down approach.\n\nBut wasnt able to do satisfactory time complexity analysis when only using recu
pritamprakash
NORMAL
2022-07-03T11:19:18.244161+00:00
2022-07-03T11:19:18.244219+00:00
73
false
I was able to solve this problem using DP in O(n^2) time + top down approach.\n\nBut wasnt able to do satisfactory time complexity analysis when only using recursion without using any DP?\n\nHas anyone done time complexity analysis when only using recusrsion without any DP ?
1
0
['Recursion']
0
stone-game-v
C++ solution. || Recursion+Memoization.
c-solution-recursionmemoization-by-samar-yrvw
\n#define ll long long\n#define vb vector<bool>\n#define vi vector<int>\n#define vl vector<long long>\n#define vvb vector<vector<bool>>\n#define vvi vector<vect
samarthya2912
NORMAL
2022-06-07T03:20:08.151053+00:00
2022-06-07T03:20:08.151084+00:00
87
false
```\n#define ll long long\n#define vb vector<bool>\n#define vi vector<int>\n#define vl vector<long long>\n#define vvb vector<vector<bool>>\n#define vvi vector<vector<int>>\n#define vvl vector<vector<long long>>\n#define pii pair<int,int>\n#define all(i) i.begin(),i.end()\n#define f(i,s,e) for(int i = s; i < e; i++)\n#define b(i,s,e) for(int i = s; i >= e; i--)\ninline int getMid(int i,int j) { return i+(j-i)/2; }\n\nclass Solution {\npublic:\n vi prefixSum;\n\n int maxScore(int i, int j, vvi& memo) {\n if(i == j) return 0;\n if(memo[i][j] != -1) return memo[i][j];\n\n int ans = 0;\n f(k,i,j) {\n int left = prefixSum[k+1]-prefixSum[i], right = prefixSum[j+1]-prefixSum[k+1];\n if(left > right) ans = max(ans,right+maxScore(k+1,j,memo));\n else if(left < right) ans = max(ans,left+maxScore(i,k,memo));\n else ans = max({ans,left+maxScore(i,k,memo),right+maxScore(k+1,j,memo)});\n }\n return memo[i][j] = ans; \n }\n\n int stoneGameV(vi& stoneValue) {\n int n = stoneValue.size();\n this->prefixSum = vi(n+1);\n prefixSum[0] = stoneValue[0];\n f(i,1,n+1) prefixSum[i] = prefixSum[i-1]+stoneValue[i-1];\n vvi memo(n,vi(n,-1));\n return maxScore(0,n-1,memo);\n }\n};\n```
1
0
[]
0
stone-game-v
ONLY GO SOLUTION | DP (only using indices)
only-go-solution-dp-only-using-indices-b-nmih
```\nfunc stoneGameV(stoneValue []int) int {\n type Key struct {\n r int\n l int\n }\n prefix := []int{0}\n curr := 0\n for _, s :=
Pedraamy
NORMAL
2022-04-20T22:52:30.618025+00:00
2022-04-20T23:03:32.602933+00:00
79
false
```\nfunc stoneGameV(stoneValue []int) int {\n type Key struct {\n r int\n l int\n }\n prefix := []int{0}\n curr := 0\n for _, s := range stoneValue {\n curr += s\n prefix = append(prefix, curr)\n }\n memo := make(map[Key]int)\n var dp func(lb int, rb int) int\n dp = func(lb int, rb int) int {\n if rb == lb {\n return 0\n }\n currKey := Key{lb, rb}\n val, exists := memo[currKey]\n if exists {\n return val\n }\n var res, curr, sl, sr int\n res = 0\n for i := lb; i < rb; i++ {\n sl = prefix[i]-prefix[lb-1]\n sr = prefix[rb]-prefix[i]\n if sl < sr {\n curr = sl+dp(lb, i)\n } else if sl > sr {\n curr = sr+dp(i+1, rb)\n } else {\n curr = Max2(sl+dp(lb, i), sr+dp(i+1, rb))\n }\n res = Max2(res, curr)\n }\n memo[currKey] = res\n return res\n }\n return dp(1, len(prefix)-1)\n}\n\nfunc Max2(c1 int, c2 int) int {\n if c2 > c1 {\n return c2\n } else {\n return c1\n }\n}
1
0
[]
0
stone-game-v
CPP/Game Theory/Highly Commented/Step-by-step/Easy Approach/N2
cppgame-theoryhighly-commentedstep-by-st-hps1
\nclass Solution {\npublic:\n int dp[501][501];\n \n// Time Complexity : O(N2)\n// Idea is to check \n// from i ...... j\n// parition the
vijaypal1621
NORMAL
2022-03-14T15:16:01.853726+00:00
2022-03-14T15:20:50.429739+00:00
101
false
```\nclass Solution {\npublic:\n int dp[501][501];\n \n// Time Complexity : O(N2)\n// Idea is to check \n// from i ...... j\n// parition the array[i...j] from k = [i to (j-1)]\n// forming two parts arr[i...k] and arr[k+1 .... j]\n// check whichever is greater, discard and recur for smaller part\n \n vector<int> pre;\n int solve(int i,int j,vector<int>&v )\n {\n if(i==j)return 0;\n \n int &x = dp[i][j];\n if(x != -1)return x;\n \n // just to calculate the total sum of array [i....j]\n int total = pre[j+1]-pre[i];\n \n int leftPartSum = 0; // to ccalculate the array sum [i...k]\n int rightPartSum;\n int ans = 0;// final ans to be returned\n for(int k=i;k<j;k++){\n leftPartSum += v[k];// adding the kth el\n rightPartSum = total - leftPartSum;\n if(leftPartSum > rightPartSum){ // if left part is greater, dicard left and recur for right part\n ans = max(ans,rightPartSum + solve(k+1,j,v) );\n }else if(leftPartSum < rightPartSum){// if right part is greater, discard right part and recur for left part\n ans = max(ans,leftPartSum + solve(i,k,v));\n }else{\n // both part have equal sum\n ans = max(ans, leftPartSum + solve(i,k,v));// recur for left\n ans = max(ans, rightPartSum + solve(k+1,j,v));// recur for right\n }\n }\n return x = ans;\n \n }\n \n \n int stoneGameV(vector<int>& v) {\n memset(dp,-1,sizeof(dp));\n int sum = 0;\n pre.push_back(0);\n for(int i=0;i<v.size();i++){\n sum += v[i];\n pre.push_back(sum);\n // cout << pre[i] << " ";\n }\n \n int ans = solve(0,v.size()-1,v);\n return ans;\n }\n};\n```
1
0
['Dynamic Programming', 'Prefix Sum']
0
stone-game-v
Do Only What is stated in the question | Noob Solution | Game Strategy
do-only-what-is-stated-in-the-question-n-ssfb
```\nclass Solution {\npublic:\n vector> dp;\n int fun(int i,int j,vector &arr,vector &pre){\n //Base Case \n if(i == j) return 0;\n
njcoder
NORMAL
2022-03-06T11:32:19.617434+00:00
2022-03-06T11:32:44.638667+00:00
115
false
```\nclass Solution {\npublic:\n vector<vector<int>> dp;\n int fun(int i,int j,vector<int> &arr,vector<int> &pre){\n //Base Case \n if(i == j) return 0;\n if(dp[i][j] != -1) return dp[i][j];\n int score = INT_MIN;\n for(int part = i+1;part <= j;part++){\n int left = pre[part-1] - (i == 0 ? 0 : pre[i-1]);\n int right = pre[j] - pre[part-1];\n if(left > right){\n score = max(score,right + fun(part,j,arr,pre)); \n }else if(left < right){\n score = max(score,left + fun(i,part-1,arr,pre));\n }else{\n score = max(score,left + fun(i,part-1,arr,pre)); \n score = max(score,right + fun(part,j,arr,pre)); \n }\n }\n return dp[i][j] = score;\n \n }\n \n int stoneGameV(vector<int>& arr) {\n int n = arr.size();\n \n vector<int> pre(n);\n pre[0] = arr[0];\n for(int i=1;i<n;i++) pre[i] = pre[i-1] + arr[i];\n dp = vector<vector<int>> (n,vector<int> (n,-1));\n return fun(0,n-1,arr,pre);\n }\n};
1
0
['Recursion', 'Memoization']
1
stone-game-v
[C++/DP and Memorization] 172 ms (94.32%) , 10.6 MB (75.68%) O(n^2)
cdp-and-memorization-172-ms-9432-106-mb-ds10f
The following algorithm is an 1-index solution.\nFirst a DP table is defined as\ndp[i][j] := the maximum score with the initial states: stones in the range from
HirofumiTsuda
NORMAL
2021-08-18T11:41:57.569137+00:00
2021-08-20T14:58:55.966878+00:00
172
false
The following algorithm is an 1-index solution.\nFirst a DP table is defined as\ndp[i][j] := the maximum score with the initial states: stones in the range from i to j (i and j are included).\nThen, there are (j - i) stones in this state. It means there are (j - i - 1) separators.\nIt is clear that the value dp[i][j] is found if all ways of setting a separator is investigated.\nTo accelerate computation, each derived value should be memorized.\n\n```\nclass Solution {\npublic:\n #define MAX 500\n int memo[MAX+2][MAX+2]; // 1-index\n int sum[MAX+2];\n int dp(int i, int j){\n if(i == j)\n return 0;\n if(memo[i][j] > 0)\n return memo[i][j];\n int ans=0;\n for(int n=i;n<j;n++){\n int left = sum[n] - sum[i-1];\n int right = sum[j] - sum[n];\n int tmp;\n if(left < right){\n tmp = dp(i,n) + left;\n }else if(right < left){\n tmp = dp(n+1, j)+right;\n }else{\n int lnum = dp(i,n);\n int rnum = dp(n+1,j);\n tmp = max(lnum, rnum) + right;\n }\n if(ans < tmp)\n ans = tmp;\n }\n memo[i][j] = ans;\n return ans;\n }\n \n int stoneGameV(vector<int>& stoneValue) {\n int N = stoneValue.size();\n int amt= 0;\n for(int i=0;i<N;i++){\n amt += stoneValue[i];\n sum[i+1] = amt;\n }\n for(int i=0;i<N-1;i++){\n memo[i+1][i+2] = min(stoneValue[i], stoneValue[i+1]);\n }\n return dp(1,N);\n }\n};\n```
1
0
[]
0
stone-game-v
Simple C++ Dynamic Programming Solution
simple-c-dynamic-programming-solution-by-f135
\nclass Solution {\npublic:\n \n int dp[505][505];\n \n int fun(vector<int>& stoneValue, int i, int j){\n \n if(i == j){\n
tanishqj2005
NORMAL
2021-07-20T17:47:05.237864+00:00
2021-07-20T17:47:05.237907+00:00
98
false
```\nclass Solution {\npublic:\n \n int dp[505][505];\n \n int fun(vector<int>& stoneValue, int i, int j){\n \n if(i == j){\n return 0;\n }\n \n if(dp[i][j] != -1){\n return dp[i][j];\n }\n \n int sum = 0, curr = 0, ans = 0;\n \n for(int k = i; k <= j; k++){\n sum += stoneValue[k];\n }\n \n for(int k = i; k < j; k++){\n \n curr += stoneValue[k];\n \n if(curr < (sum - curr)){\n ans = max(ans,fun(stoneValue,i,k) + curr);\n }\n else if(curr > (sum - curr)){\n ans = max(ans,fun(stoneValue,k+1,j) + (sum - curr));\n }\n else{\n ans = max(ans, curr + max(fun(stoneValue,i,k),fun(stoneValue,k+1,j)));\n }\n \n }\n \n dp[i][j] = ans;\n \n return ans;\n \n }\n \n int stoneGameV(vector<int>& stoneValue) {\n \n int size = stoneValue.size();\n memset(dp,-1,sizeof(dp));\n \n return fun(stoneValue,0,size-1);\n }\n};\n\n```
1
0
[]
0
stone-game-v
Top down DP | Commented
top-down-dp-commented-by-apooos3-297p
\nclass Solution {\n public int stoneGameV(int[] s) {\n int n = s.length;\n\t\t//prefix array so that difference between left and right can be calcula
apooos3
NORMAL
2021-06-11T18:59:12.892598+00:00
2021-06-11T19:02:59.100933+00:00
312
false
```\nclass Solution {\n public int stoneGameV(int[] s) {\n int n = s.length;\n\t\t//prefix array so that difference between left and right can be calculated in O(1)\n int[] prefix = new int[n];\n\t\t//2D DP array for each cut (length) vs. elements containing the actual sum\n int[][] dp = new int[n][n];\n prefix[0] = s[0];\n for(int i=1; i<n; i++) {\n prefix[i] = prefix[i-1] + s[i];\n }\n \n return minimax5(s, prefix, 0, n-1, dp);\n }\n\n private int minimax5(int[] stones, int[] pre, int s, int e, int[][] dp) {\n\t\t//base case: no profit as game ends when there\'s only one stone left\n if(s==e) {\n return 0;\n }\n\t\t//return the memoized solution\n if(dp[s][e]!=0) return dp[s][e];\n int sum = 0, ans = Integer.MIN_VALUE;\n\t\t//make a cut at each length and find the one with maximum profit\n for(int i=s; i<e; i++) {\n int left = s == 0? 0 : pre[s-1];\n\t\t\t//calculate left and right sum at the cut using prefix array built earlier\n int pl = pre[i] - left; int pr = pre[e] - pre[i];\n sum = Math.min(pl, pr);\n \n\t\t\t//pick the one with lower value as the larger one will be thrown\n\t\t\t//in case of equal partition, we need to look both ways and find the one that returns maximum value\n if(pl>pr) {\n sum += minimax5(stones, pre, i+1, e, dp);\n }else if(pl<pr) {\n sum += minimax5(stones, pre, s, i, dp);\n }else{\n sum += \n Math.max(minimax5(stones, pre, i+1, e, dp), minimax5(stones, pre, s, i, dp));\n }\n //save the overall maximum\n ans = Math.max(ans, sum);\n }\n //memoize the answer and return\n return dp[s][e]=ans;\n }\n}\n```\n\nHowever, I am not sure what would be it\'s time complexity (seems O(n^3) but not sure). If anyone can explain, that\'d be very helpful.
1
0
['Dynamic Programming', 'Memoization', 'Java']
0
stone-game-v
DP n^3 with optimisation and elimination. Detailed explanation. [Latest] [Python]
dp-n3-with-optimisation-and-elimination-isryp
The idea of elimiation was based on GP and inspired from @Prezes Code. In O(n^3) we trim some corner cases. Like if we are itterating over different partionions
glastonbury
NORMAL
2021-06-04T19:46:12.451498+00:00
2021-06-04T19:49:35.265342+00:00
155
false
The idea of elimiation was based on GP and inspired from @Prezes Code. In O(n^3) we trim some corner cases. Like if we are itterating over different partionions for a given subarray(start,end) we keep track of what is the max from any given subarry. Now when we compute leftRow Sum and rightRow sum we apply an elimation logic. Let\'s sat leftRow was smaller and got selected for next round . Now what is the maxValue we can get from left Row in best case scenario? So lets say the sum of leftRow is X. So X will be directly added to points. But what is the maximum value possible from this X in remaining rounds without actually checking? It will be when X splits equally in two X/2 and X/2 and bob removes X/2 and adds the other X/2 to points, which further goes for next round (X/2 that remained) and in best case splits in X/4 and X/4 and bob will removes one X/4 and other X/4 will go to your point and similarly it goes on.. So the best case points will be X +X/2 +X/4 +X/8 +X/16 = X/(1-1/2) = X/(1/2) =2X. \nSo for any distribution of X, the remaining sum wont go beyond this. We compare this with current max. If it is less than current max then in now that sub partition can form a sum more than max.\nSo we compare- if 2*(sumOfSlectedRow)<=max then skip\nTime - worst case may go upto n^3 but average case will be much much better. 76% faster than others\nMemory - O(n^2) beats 95%\n```\nclass Solution:\n def stoneGameV(self, sv: List[int]) -> int:\n n=len(sv)\n sv.append(0)\n for i in range(n-1,-1,-1):\n sv[i]+=sv[i+1]\n #sv now stores the sum. sv[i]= sum of all stones from ith postion to end \n \n @lru_cache(None)\n def getMax(startIndex,endIndex):\n # We start solving a subProblem as to maximum score alice can get for subarray from startIndex to endIndex\n \n #if start==end that means only one element left in subarray. You can only get zero. like for [6] \n # you will make pile [6] and[0] and bob will remove [6] leaving you with zero\n if (endIndex==startIndex):\n return 0\n \n # Now we start making partitons. Remember- Having one row empty will be useless as it will give zero\n # lets say startIndex=3 and endIndex is 6, So we itterate over partions as :\n # [3] [4,5,6]; [3,4] [5,6]; [3,4,5] [6]. So leftRow will contain startIndex to ith element\n # Also note we do not incude endIndexin loop as it would cause right row to be empty\n for i in range(startIndex,endIndex):\n \n left=[startIndex,i]\n right=[i+1,endIndex]\n \n #we wont calculate sum each time. Rather use precomputed sum array to get sum from i to j in 0(1)\n leftSum=sv[startIndex]-sv[i+1]\n rightSum=sv[i+1]-sv[endIndex+1]\n \n # min(leftSum,rightSum) represents the sum of row that is selected.\n # Now calue you can get from it will be sum + sum/2 + sum/4 .... = 2*sum\n # if this is less than currentMax , then it can never form next max. So skip\n # i>startIndex is just to check if it is the first element we are starting or if there is a previous max\n if i>startIndex and 2*min(leftSum,rightSum)<maxi:\n continue\n if leftSum>rightSum:\n last=getMax(right[0],right[1])\n value=rightSum+last\n elif rightSum>leftSum:\n last=getMax(left[0],left[1])\n value=leftSum+last\n else :\n last=getMax(right[0],right[1])\n value=max(leftSum+getMax(left[0],left[1]),rightSum+getMax(right[0],right[1]))\n \n # if we have a previous max Value compare it with it. If greater so we have find a new partion for\n # given subarray that gives more points to alice\n if i>startIndex:\n maxi=max(maxi,value)\n else:\n maxi=value\n result = maxi \n return result\n \n \n return getMax(0,n-1)\n```
1
1
[]
0
stone-game-v
Recursion ->DP
recursion-dp-by-sinhaneha455-cm9x
TLE Error Recursion Code\n\n public int solve(int si , int ei , int[]arr){\n \n if(si>ei){\n return 0;\n }\n \n in
sinhaneha455
NORMAL
2021-05-11T12:59:44.921023+00:00
2021-05-11T13:00:20.543162+00:00
311
false
**TLE Error Recursion Code**\n```\n public int solve(int si , int ei , int[]arr){\n \n if(si>ei){\n return 0;\n }\n \n int rightPart =0 , leftPart=0 , result=0;\n \n for(int i=si;i<=ei;i++){\n rightPart+=arr[i];\n }\n \n for(int i=si;i<ei;i++){\n leftPart+=arr[i];\n rightPart-=arr[i];\n \n \n // bob will throw maximum one so we need to add the leftpart in our result\n if(leftPart<rightPart)result = Math.max(result , leftPart+solve(si , i , arr));\n // bob will throw maximum one so we need to add the rightpart in our result\n if(leftPart>rightPart)result = Math.max(result , rightPart+solve(i+1, ei , arr)); \n //if both are equal then alice will decide which need to be thrown \n if(leftPart==rightPart) result = Math.max(result , leftPart + Math.max(solve(si , i , arr) , solve(i+1 , ei , arr)));\n \n \n \n }\n \n return result;\n }\n```\n\n\n**Dp Top down **\n\n\n```\n public int solve(int si , int ei , int[]arr , int[][] strg){\n \n if(si>ei){\n return 0;\n }\n if(strg[si][ei]!=-1){\n return strg[si][ei];\n }\n int rightPart =0 , leftPart=0 , result=0;\n \n for(int i=si;i<=ei;i++){\n rightPart+=arr[i];\n }\n \n for(int i=si;i<ei;i++){\n leftPart+=arr[i];\n rightPart-=arr[i];\n \n \n // bob will throw maximum one so we need to add the leftpart in our result\n if(leftPart<rightPart)result = Math.max(result , leftPart+solve(si , i , arr , strg));\n // bob will throw maximum one so we need to add the rightpart in our result\n if(leftPart>rightPart)result = Math.max(result , rightPart+solve(i+1, ei , arr , strg)); \n //if both are equal then alice will decide which need to be thrown \n if(leftPart==rightPart) result = Math.max(result , leftPart + Math.max(solve(si , i , arr , strg) , solve(i+1 , ei , arr , strg)));\n \n \n \n }\n strg[si][ei]=result;\n return result;\n }\n```\n
1
0
['Dynamic Programming', 'Recursion', 'Java']
0
stone-game-v
C# solution using Memoization and Prefix Sum
c-solution-using-memoization-and-prefix-psz82
\npublic class Solution {\n int[,] dp;\n int[] prefix;\n public int Solve(int[] arr, int i, int j)\n {\n if(i>=j) return 0;\n if(dp[i,
aj936563
NORMAL
2021-05-08T11:10:30.118437+00:00
2021-05-08T11:10:30.118465+00:00
56
false
```\npublic class Solution {\n int[,] dp;\n int[] prefix;\n public int Solve(int[] arr, int i, int j)\n {\n if(i>=j) return 0;\n if(dp[i,j]!=0) return dp[i,j];\n int res = 0;\n for(int k=i;k<=j;k++)\n {\n int left = prefix[k+1] - prefix[i];\n int right = prefix[j+1] - prefix[k+1];\n if(left>right)\n {\n res = Math.Max(res, right + Solve(arr,k+1,j));\n }\n else if(left<right)\n {\n res = Math.Max(res, left + Solve(arr,i,k));\n }\n else\n {\n res = Math.Max(res, right + Math.Max(Solve(arr,i,k),Solve(arr,k+1,j)));\n }\n \n }\n \n dp[i,j] = res;\n return res;\n \n }\n public int StoneGameV(int[] stoneValue) {\n int n = stoneValue.Count();\n dp = new int[n,n];\n prefix = new int[n+1];\n prefix[0] = 0;\n for(int i=0;i<n;i++)\n {\n prefix[i+1] = prefix[i] + stoneValue[i];\n }\n return Solve(stoneValue,0,n-1);\n }\n}\n```
1
0
[]
0
stone-game-v
100% (T), 100%(S) :: C / Python - Memoization
100-t-100s-c-python-memoization-by-tuhin-lmm6
Down below, you\'ll find C and Python implementations for the same. Funny how a 100% faster C solution exceeds the allotted time limit when coded in Python, The
tuhinnn_py
NORMAL
2021-05-06T15:09:39.632686+00:00
2021-05-06T15:09:39.632717+00:00
254
false
Down below, you\'ll find C and Python implementations for the same. Funny how a 100% faster C solution exceeds the allotted time limit when coded in Python, The code is pretty self explanatory. Let me know if you still need help in the comments below.\n\n**C**\n\n```\nint dp[501][501];\n\nint max(int a, int b)\n{\n return (a > b)? a: b;\n}\n\nint playGame(int* sumValue, int* arr, int i, int j)\n{\n if(dp[i][j] != -1)\n return dp[i][j];\n if(i == j)\n {\n dp[i][j] = 0;\n return 0;\n }\n int res, k, ans = 0;\n for(k = i; k < j; k++)\n {\n int left = sumValue[k + 1] - sumValue[i], right = sumValue[j + 1] - sumValue[k + 1];\n if(left > right)\n res = right + playGame(sumValue, arr, k + 1, j); \n else if(left < right)\n res = left + playGame(sumValue, arr, i, k); \n else\n res = max(left + playGame(sumValue, arr, i, k), right + playGame(sumValue, arr, k + 1, j)); \n ans = max(ans, res);\n }\n dp[i][j] = ans;\n return ans;\n}\n\nint stoneGameV(int* stoneValue, int stoneValueSize)\n{\n memset(dp, -1, sizeof(dp));\n if(stoneValueSize == 1)\n return 0;\n \n int i;\n int* sumValue = (int*)malloc(sizeof(int) * (stoneValueSize + 1));\n sumValue[0] = 0;\n sumValue[1] = stoneValue[0];\n \n for(i = 1; i < stoneValueSize; i++)\n sumValue[i + 1] = sumValue[i] + stoneValue[i];\n \n return playGame(sumValue, stoneValue, 0, stoneValueSize - 1);\n}\n```\n\n**Python**\n\n```\nfrom functools import lru_cache\nclass Solution:\n def stoneGameV(self, arr: List[int]) -> int:\n if len(arr) == 1:\n return 0\n \n sumValue = [0, arr[0]]\n for i in range(1, len(arr)):\n sumValue.append(sumValue[-1] + arr[i])\n \n @lru_cache(None)\n def playGame(i, j):\n if i == j:\n return 0\n ans = 0\n for k in range(i, j):\n left, right = sumValue[k + 1] - sumValue[i], sumValue[j + 1] - sumValue[k + 1] \n # sum(arr[i: k + 1]), sum(arr[k + 1: j + 1])\n if left > right:\n res = right + playGame(k + 1, j) \n elif left < right:\n res = left + playGame(i, k) \n else:\n res = max(left + playGame(i, k), right + playGame(k + 1, j)) \n ans = max(ans, res)\n return ans\n return playGame(0, len(arr) - 1)\n```
1
0
['Memoization', 'C', 'Python']
1
stone-game-v
80ms C++ DP and reduce branches
80ms-c-dp-and-reduce-branches-by-mz1007-veqv
The key to accelerate the code is to reduce branches (if(2*min(sumL, sumR) < tmp) continue;), which helps to reduce runtime from 800ms to 80ms (faster than 97%)
mz1007
NORMAL
2021-03-29T14:14:43.637621+00:00
2021-03-30T18:38:10.513341+00:00
152
false
The key to accelerate the code is to reduce branches (`if(2*min(sumL, sumR) < tmp) continue;`), which helps to reduce runtime from 800ms to 80ms (faster than 97%).\n```c++\nclass Solution {\npublic:\n int stoneGameV(vector<int>& v) {\n //dp[i][j]: max scores obtained from v[i:j]\n //dp[i][j] = max{ ( sum(v[i:k]) < sum(v[k+1:j]) ) ? sum(v[i:k]) + dp[i][k] : sum(v[k+1:j]) + dp[k+1][j] } for k in [i,j-1]\n int n = v.size();\n if(n == 1) return 0;\n vector<int> sum(n, 0);\n int lsum = 0;\n for(int i = 0; i < n; i++) sum[i] = lsum = lsum + v[i];\n vector<vector<int>> dp(n, vector<int>(n, 0));\n function<int(int,int)> helper = [&](int i, int j){ \n if(i == j) return 0;\n if(dp[i][j]) return dp[i][j];\n int tmp = 0;\n int init = i > 0 ? sum[i-1] : 0; //careful\n for(int k = i; k <= j-1; k++){ //careful about range of k\n int sumL = sum[k] - init;\n int sumR = sum[j] - sum[k];\n if(2*min(sumL, sumR) < tmp) continue; //key to reduce the runtime: 2*min(sumL, sumR) is the score upper bound for this cut (reduce runtime from 800ms to 80ms)\n if(sumL != sumR) tmp = max(tmp, (sumL<sumR) ? sumL + helper(i,k) : sumR + helper(k+1,j));\n else tmp = max(tmp, max(sumL + helper(i,k), sumR + helper(k+1,j)));\n }\n return dp[i][j] = tmp;\n };\n return helper(0, n-1);\n }\n};\n\n```
1
0
[]
2
stone-game-v
Javascript beats 100% time and 100% memory (368ms, 39.4mb)
javascript-beats-100-time-and-100-memory-lysu
\nvar stoneGameV = function(stones) {\n let bestAns = 0\n let stoneSum = stones.reduce((sum, current)=> {return sum+ current},0)\n\n function splitAndA
raphyhayes
NORMAL
2021-03-22T20:18:35.767200+00:00
2021-03-22T20:30:35.880266+00:00
135
false
```\nvar stoneGameV = function(stones) {\n let bestAns = 0\n let stoneSum = stones.reduce((sum, current)=> {return sum+ current},0)\n\n function splitAndAdd(stoneSum, ans, leftBound,rightBound){\n\t\n if (rightBound === leftBound){return ans}\n\n if (rightBound - leftBound === 1){\n return ans + Math.min(stones[leftBound], stones[rightBound])\n }\n let bestSoFar = 0\n let leftSum = 0\n let rightSum = stoneSum\n for(let i = leftBound; i <= rightBound; i++){\n leftSum += stones[i]\n rightSum -=stones[i]\n \n \n if (2* Math.min(leftSum, rightSum) + ans < bestAns){continue} \n if (leftSum === rightSum){\n bestSoFar = Math.max(splitAndAdd(leftSum, ans+leftSum, leftBound,i), bestSoFar)\n bestSoFar = Math.max(splitAndAdd(rightSum, ans+rightSum, i+1, rightBound), bestSoFar)\n \n } else{\n \n leftSum > rightSum\n ? bestSoFar = Math.max(splitAndAdd(rightSum, ans+rightSum, i+1, rightBound),bestSoFar)\n : bestSoFar = Math.max(splitAndAdd(leftSum, ans+leftSum, leftBound, i), bestSoFar)\n }\n \n }\n \n bestAns = Math.max(bestAns, bestSoFar)\n return bestSoFar\n }\n \n \n let ans = splitAndAdd(stoneSum, 0, 0, stones.length-1)\n return ans\n \n};\n```
1
0
['JavaScript']
1
stone-game-v
C++ Solution [Recursive Memoization ]
c-solution-recursive-memoization-by-sha_-nxh8
\nclass Solution {\npublic:\n \n vector<int> presum;\n \n vector<vector<int>> dp;\n \n vector<int> stones;\n \n int solve(int i,int j)\n
sha_256
NORMAL
2021-01-07T07:08:28.336630+00:00
2021-01-07T07:08:28.336664+00:00
110
false
```\nclass Solution {\npublic:\n \n vector<int> presum;\n \n vector<vector<int>> dp;\n \n vector<int> stones;\n \n int solve(int i,int j)\n {\n \n\n\n if(i>j)\n return 0;\n\n \n if(i == j)\n return 0;\n \n \n if(j-i == 1)\n {\n return min(stones[i],stones[j]);\n }\n \n if(dp[i][j]!=-1)\n return dp[i][j];\n \n int ans = 0;\n \n \n for(int k = i;k<j;k++)\n {\n \n \n int pre_;\n \n if(i-1 <0)\n {\n pre_ = 0;\n }\n else\n {\n pre_ = presum[i-1];\n }\n \n if(presum[k]-pre_>presum[j]-presum[k])\n {\n int temp = solve(k+1,j);\n int x_ = presum[j]-presum[k];\n ans = max(ans,temp+x_);\n }\n else if(presum[k]-pre_<presum[j]-presum[k])\n {\n int temp = solve(i,k);\n int x_ = presum[k]-pre_;\n ans = max(ans,temp+x_);\n }\n else\n {\n \n int temp1 = solve(k+1,j)+presum[j]-presum[k];\n int temp2 = solve(i,k)+presum[k]-pre_;\n ans = max(ans,max(temp1,temp2));\n \n } \n \n }\n return dp[i][j] = ans;\n }\n \n \n \n int stoneGameV(vector<int>& stoneValue) {\n \n \n \n dp.resize(stoneValue.size()+1,vector<int>(stoneValue.size()+1,-1));\n presum.resize(stoneValue.size(),0);\n stones = stoneValue;\n \n presum[0] = stoneValue[0]; \n for(int i = 1;i<stoneValue.size();i++)\n {\n presum[i] = presum[i-1]+stoneValue[i];\n }\n \n \n return solve(0,stoneValue.size()-1);\n }\n};\n```
1
0
[]
0
stone-game-v
C++ | DP | ft. Prefix - Sum | Clean Code.
c-dp-ft-prefix-sum-clean-code-by-lekhesh-syum
\n\nclass Solution {\npublic:\n int dp[501][501];\n int prefixSum[501];\n \n int helper(vector<int>& s, int l, int r){\n \n if(l >= r)
lekhesh12
NORMAL
2020-10-26T18:03:31.100195+00:00
2020-10-26T18:03:31.100248+00:00
116
false
\n```\nclass Solution {\npublic:\n int dp[501][501];\n int prefixSum[501];\n \n int helper(vector<int>& s, int l, int r){\n \n if(l >= r) return 0; // BASE case\n \n if(dp[l][r] != -1)return dp[l][r]; // Return pre commputed sub-problem.\n \n int ans = INT_MIN;\n \n for(int i = 0; i < r-l; i++){ // You can only break the array at l+0, l+1, l+2,.....r-1 th index.\n \n int L = prefixSum[l+i+1] - prefixSum[l];\n int R = prefixSum[r+1] - prefixSum[l+i+1];\n \n if(L < R){\n int temp = dp[l][l+i] == -1 ? helper(s, l, l+i) : dp[l][l+i];\n ans = max(ans, L + temp);\n }\n else if (R < L){\n int temp = dp[l+i+1][r] == -1 ? helper(s, l + i + 1, r) : dp[l+i+1][r];\n ans = max(ans, temp + R);\n }\n else{\n int temp1 = dp[l][l+i] == -1 ? helper(s, l, l+i) : dp[l][l+i];\n int temp2 = dp[l+i+1][r] == -1 ? helper(s, l + i + 1, r) : dp[l+i+1][r];\n ans = max(ans, L + max(temp1, temp2));\n }\n }\n return dp[l][r] = ans;\n }\n \n \n int stoneGameV(vector<int>& stoneValue) {\n int ans = INT_MIN;\n memset(dp, -1, sizeof dp);\n int n = stoneValue.size();\n \n prefixSum[0] = 0; // Prefix sum is used to optimize the intermediate Range Sum...\n \n for(int i = 0; i < n; i++)prefixSum[i+1] = prefixSum[i] + stoneValue[i];\n \n ans = helper(stoneValue, 0, n - 1);\n \n return ans;\n }\n};\n```\n
1
0
[]
0
stone-game-v
Java solution from brute-force to DP O(n^3)
java-solution-from-brute-force-to-dp-on3-gbyg
Solution brute-force - Time Limit Exceeded \n\npublic class StoneGameVRecursiveApproach {\n public static void main(String[] args) {\n int[] stoneGame
akiramonster
NORMAL
2020-10-04T22:37:44.193620+00:00
2020-10-04T22:37:44.193664+00:00
99
false
Solution brute-force - Time Limit Exceeded \n```\npublic class StoneGameVRecursiveApproach {\n public static void main(String[] args) {\n int[] stoneGame = {6, 2, 3, 4, 5, 5};\n System.out.println(stoneGameV(stoneGame));\n }\n\n public static int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = createPrefixSum(stoneValue);\n return stoneGameV(0, n - 1, sum);\n }\n\n private static int stoneGameV(int i, int k, int[] sum) {\n if (i >= k) return 0;\n int maxScore = Integer.MIN_VALUE;\n for (int j = i; j < k; j++) { // divides to 2 rows (i, j), (j+1, k)\n int sum1 = sum[j + 1] - sum[i]; // sum from i -> j inclusive\n int sum2 = sum[k + 1] - sum[j + 1]; // sum from j+1 -> k inclusive\n if (sum1 > sum2) { // Bob removes left\n maxScore = Math.max(maxScore, stoneGameV(j + 1, k, sum) + sum2);\n } else if (sum1 < sum2) { // Bob removes right\n maxScore = Math.max(maxScore, stoneGameV(i, j, sum) + sum1);\n } else { // Bob let Alice to decide which rows will be removed.\n maxScore = Math.max(maxScore, Math.max(stoneGameV(i, j, sum), stoneGameV(j + 1, k, sum)) + sum1);\n }\n }\n return maxScore;\n }\n\n private static int[] createPrefixSum(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = new int[n + 1];\n for (int i = 0; i < n; i++) sum[i + 1] = sum[i] + stoneValue[i];\n return sum;\n }\n}\n\n```\n\nSolution uses memoization\n```\npublic class StoneGameVMemoizationApproach {\n public static void main(String[] args) {\n int[] stoneGame = {6, 2, 3, 4, 5, 5};\n System.out.println(stoneGameV(stoneGame));\n }\n\n public static int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = createPrefixSum(stoneValue);\n int[][] memo = new int[n][n];\n stoneGameV(0, n - 1, sum, memo);\n return memo[0][n - 1];\n }\n\n private static int stoneGameV(int i, int k, int[] sum, int[][] memo) {\n if (i >= k) return 0;\n if (memo[i][k] > 0) return memo[i][k];\n int maxScore = Integer.MIN_VALUE;\n for (int j = i; j < k; j++) { // divides to 2 rows (i, j), (j+1, k)\n int sum1 = sum[j + 1] - sum[i]; // sum from i -> j inclusive\n int sum2 = sum[k + 1] - sum[j + 1]; // sum from j+1 -> k inclusive\n if (sum1 > sum2) { // Bob removes left\n maxScore = Math.max(maxScore, stoneGameV(j + 1, k, sum, memo) + sum2);\n } else if (sum1 < sum2) { // Bob removes right\n maxScore = Math.max(maxScore, stoneGameV(i, j, sum, memo) + sum1);\n } else { // Bob let Alice to decide which rows will be removed.\n maxScore = Math.max(maxScore, Math.max(stoneGameV(i, j, sum, memo), stoneGameV(j + 1, k, sum, memo)) + sum1);\n }\n }\n memo[i][k] = maxScore;\n return maxScore;\n }\n\n private static int[] createPrefixSum(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = new int[n + 1];\n for (int i = 0; i < n; i++) sum[i + 1] = sum[i] + stoneValue[i];\n return sum;\n }\n}\n```\n\nSolution uses DP Bottom-up\n```\n\npublic class StoneGameVBottomUpApproach {\n public static void main(String[] args) {\n int[] stoneGame = {6, 2, 3, 4, 5, 5};\n System.out.println(stoneGameV(stoneGame));\n }\n\n public static int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = createPrefixSum(stoneValue);\n int[][] dp = new int[n][n];\n for (int i = n - 1; i >= 0; i--) {\n for (int k = 0; k < n; k++) {\n if (i >= k) continue;\n dp[i][k] = Integer.MIN_VALUE;\n for (int j = i; j < k; j++) { // divides to 2 rows (i, j), (j+1, k)\n int sum1 = sum[j + 1] - sum[i]; // sum from i -> j inclusive\n int sum2 = sum[k + 1] - sum[j + 1]; // sum from j+1 -> k inclusive\n if (sum1 > sum2) { // Bob removes left\n dp[i][k] = Math.max(dp[i][k], dp[j + 1][k] + sum2);\n } else if (sum1 < sum2) { // Bob removes right\n dp[i][k] = Math.max(dp[i][k], dp[i][j] + sum1);\n } else { // Bob let Alice to decide which rows will be removed.\n dp[i][k] = Math.max(dp[i][k], Math.max(dp[i][j], dp[j + 1][k]) + sum1);\n }\n }\n }\n }\n return dp[0][n - 1];\n }\n\n private static int[] createPrefixSum(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = new int[n + 1];\n for (int i = 0; i < n; i++) sum[i + 1] = sum[i] + stoneValue[i];\n return sum;\n }\n}\n```\nReference: https://leetcode.com/problems/stone-game-v/discuss/870497/Java-Recursive-greater-Memoization-greater-2D-Bottom-Up\n
1
0
[]
0
stone-game-v
Over-commented code for Stone Game V (1563)
over-commented-code-for-stone-game-v-156-bi2b
Hopefully this helps some folks. Over-commented :-)\n\nclass Solution {\npublic:\n int sgv( int b, /* Beginning index of row of stone
tktripathy
NORMAL
2020-09-10T02:16:53.689418+00:00
2020-09-10T02:23:44.386236+00:00
148
false
Hopefully this helps some folks. Over-commented :-)\n```\nclass Solution {\npublic:\n int sgv( int b, /* Beginning index of row of stones */\n int e, /* Ending index of row */\n vector<int>& s, /* Original row of stones - prefix-summed */\n vector<vector<int>>& memo) /* Memo to not TLE */\n {\n int m/*ax score*/ = 0;\n \n /* Return if we have seen this answer from before */\n if (memo[b][e] != -1) return memo[b][e];\n\n for (int i = b; i < e; i++) {\n int t = 0;\n /* \n * Alice divides the row into two different rows -\n * left (b - i) and right (i+1 - e). Bob now calculates\n * total sums using precomputed prefix sums.\n */\n int l = s[i] - (b ? s[b - 1] : 0);\n int r = s[e] - s[i]; \n if (l == r) { /* Alice gets a chance to pick. So, here she\n * evaluates both rows for max possible score.\n */\n t = l + /* Score Alice has now */\n max(sgv(b, i, s, memo), /* Score from recursion on left row */\n sgv(i+1, e, s, memo));/* Score from recursion on right row */\n } else if (l > r ) { /* Bob throws away left row */\n t = r + /* Score Alice has now - right row sum */ \n sgv(i+1, e, s, memo); /* Score from recursion on the right row */\n } else { /* Bob throws away right row */\n t = l + /* Score Alice has now - left row sum */\n sgv(b, i, s, memo); /* Score from recursion on the left row */\n }\n m = max(m, t); /* The max score that Alice can get */\n }\n \n /* Remember the max score that Alice can get if \n * she has a row of stones beginning at b and \n * ending in e\n */\n return memo[b][e] = m;\n }\n \n int stoneGameV(vector<int>& s) {\n vector<vector<int>> memo(501, vector<int>(501, -1));\n for (int i = 1; i < s.size(); i++) s[i] += s[i-1]; /* prefix sum */\n return sgv(0, s.size() - 1, s, memo);\n }\n};\n```
1
0
[]
1
stone-game-v
[Python] Need help with TLE | DP O(n^3)
python-need-help-with-tle-dp-on3-by-zhen-ue2b
126/131 cases passed. I used lru to cache results from function. \n\nclass Solution:\n def stoneGameV(self, stoneValue: List[int]) -> int:\n # stoneVa
zhenglun
NORMAL
2020-09-01T03:25:39.446560+00:00
2020-09-01T03:25:39.446605+00:00
269
false
126/131 cases passed. I used lru to cache results from function. \n```\nclass Solution:\n def stoneGameV(self, stoneValue: List[int]) -> int:\n # stoneValue\n prefix = [0] \n for v in stoneValue:\n prefix.append(prefix[-1]+v)\n @lru_cache(None)\n def dp(i, j):\n if i == j:\n return 0\n val = 0\n for cut in range(i, j):\n l, r = prefix[cut+1] - prefix[i], prefix[j+1] - prefix[cut+1]\n if l > r:\n val = max(val, r+dp(cut+1, j))\n elif l < r:\n val = max(val, l+dp(i, cut))\n else:\n val = max(val, l+dp(i, cut), r+dp(cut+1, j))\n return val\n return dp(0, len(stoneValue)-1)\n```
1
0
['Python']
1
stone-game-v
[Java] Easy Bottom Up O(N^3)
java-easy-bottom-up-on3-by-lancewang-fra5
```\n\npublic int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = new int[n + 1];\n \n for(int i = 0; i <
lancewang
NORMAL
2020-08-30T03:28:31.326601+00:00
2020-08-30T03:43:35.741919+00:00
86
false
```\n\npublic int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] sum = new int[n + 1];\n \n for(int i = 0; i < n; i++){\n sum[i+1] = sum[i] + stoneValue[i];\n }\n \n int[][] dp = new int[n + 1][n + 1];\n \n for(int len = 2; len <= n; len++){\n for(int i = 0; i + len <= n; i++){\n int j = i + len;\n \n for(int k = i + 1; k < j; k++){\n int left = sum[k] - sum[i];\n int right = sum[j] - sum[k];\n \n if(left <= right){\n dp[i][j] = Math.max(dp[i][j], left + dp[i][k]);\n }\n \n if(right <= left){\n dp[i][j] = Math.max(dp[i][j], right + dp[k][j]);\n }\n }\n }\n }\n \n return dp[0][n];\n }\n\t
1
0
[]
0
stone-game-v
well comment and easy to understand..
well-comment-and-easy-to-understand-by-f-26z3
We are going to explore all the devisior of stoneValue and maintain a sum...\nat any position there could be 3 condition\n1.leftsum is greater then right sum\n\
faltu_admi
NORMAL
2020-08-29T05:07:26.349298+00:00
2020-08-29T05:07:26.349348+00:00
125
false
We are going to explore all the devisior of stoneValue and maintain a sum...\nat any position there could be 3 condition\n1.leftsum is greater then right sum\n\tin this case bob will through out left part and alice got the point as right sum and rest of game start with right part of stoneValue\n2.right sum is greater then left sum\n\tin this case bob will through out right part and alice got the point as left sum and rest of game start with left part of stoneValue\n3.both are equal\n\tlet\'s play the alice as both above 1 and 2 condition and decide which one is better\n```\nint solve( vector<int> &sum ,int **dp, int left , int right ){\n\tif(left>right) return 0;//invalid interavel\n\tint &ans=dp[left][right];\n\tif(ans!=-1) return ans;\n\tfor(int i=left ; i<=right ; i++){\n\t\tint leftSum=sum[i]-sum[left-1];//get the left sum and get the right sum\n\t\tint rightSum=sum[right]-sum[i];\n\t\tif(leftSum>rightSum){\n\t\t\t//left sum will be through out\n\t\t\tans=max(ans , rightSum+solve(sum, dp ,i+1 ,right));\n\t\t}else if(leftSum<rightSum){\n\t\t\t//right sum will be through out\n\t\t\tans=max(ans , leftSum+solve(sum, dp , left , i));\n\t\t}else{\n\t\t\t//let\'s find both way\n\t\t\tans=max(ans , max(rightSum+solve(sum ,dp, i+1 , right) , leftSum+solve(sum ,dp, left , i)));\n\t\t}\n\t}\n\treturn ans;\n}\nint stoneGameV(vector<int>& stoneValue) {\n\tint n=stoneValue.size();\n\tvector<int> sum(n+1);\n\tint **dp=new int*[n+1];\n\tsum[0]=0;\n\tfor(int i=0 ; i<=n;i++){\n\t\tdp[i]=new int[n+1];\n\t\tif(i) sum[i]=sum[i-1]+stoneValue[i-1];\n\t\tfor(int j=0 ; j<=n ; j++) dp[i][j]=-1;\n\t}\n\treturn solve(sum,dp ,1 , stoneValue.size());\n}\n```\nHappy coding!!!
1
0
[]
0
stone-game-v
Easy JAVA dp solution
easy-java-dp-solution-by-virti-4co0
\nclass Solution {\n Integer dp[][];\n public int stoneGameV(int[] stoneValue) {\n dp=new Integer[stoneValue.length][stoneValue.length];\n f
virti
NORMAL
2020-08-24T16:07:17.295591+00:00
2020-08-24T16:07:54.527030+00:00
109
false
```\nclass Solution {\n Integer dp[][];\n public int stoneGameV(int[] stoneValue) {\n dp=new Integer[stoneValue.length][stoneValue.length];\n for(int i=1;i<stoneValue.length;i++) stoneValue[i]+=stoneValue[i-1];\n return check(0,stoneValue.length-1,stoneValue);\n }\n public int check(int i, int j, int arr[]){\n if(dp[i][j]!=null) return dp[i][j];\n if(i>=j) return dp[i][j]=0;\n int ans=0,b=(i==0)?0:arr[i-1];\n for(int a=i;a<j;a++){\n int c=arr[j]-arr[a];\n if(c>arr[a]-b) ans=Math.max(ans, arr[a]-b+check(i,a,arr));\n else if(c<arr[a]-b) ans=Math.max(ans, c+check(a+1,j,arr));\n else ans=Math.max(arr[a]-b+check(i,a,arr),c+check(a+1,j,arr));\n }\n return dp[i][j]=ans;\n }\n}\n```\n
1
0
['Dynamic Programming']
0
stone-game-v
easy DP solution using cumulative sum (JAVA)
easy-dp-solution-using-cumulative-sum-ja-0em4
\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n int n= stoneValue.length;\n if(n==1) return 0;\n int A[]= new int[n+1];
nrjain1997
NORMAL
2020-08-24T12:31:39.869105+00:00
2020-08-24T12:31:39.869153+00:00
83
false
```\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n int n= stoneValue.length;\n if(n==1) return 0;\n int A[]= new int[n+1];\n int dp[][] = new int[n+1][n+1];\n for(int[] x:dp)Arrays.fill(x,-1);\n A[0]=0;\n for(int i=1;i<n+1;i++) A[i]=A[i-1]+stoneValue[i-1];\n System.out.println(Arrays.toString(A)); \n return dfs(dp,0,n-1,A,stoneValue); \n }\n public int dfs(int dp[][],int i, int j,int A[],int arr[]){\n if(j<=i) return dp[i][j]=0;\n if(dp[i][j]!=-1) return dp[i][j]; \n int max =Integer.MIN_VALUE;\n for(int k=i+1;k<=j;k++){\n int left =A[k]-A[i];\n int right = A[j+1]-A[k];\n int a;\n if(left<right)\n a =left+dfs(dp,i,k-1,A,arr);\n else if(right<left)\n a =right+dfs(dp,k,j,A,arr);\n else\n a=left+ Math.max(dfs(dp,i,k-1,A,arr),dfs(dp,k,j,A,arr)); \n max= Math.max(a,max); \n }\n dp[i][j]=max;\n return dp[i][j];\n }\n}\n```
1
0
['Dynamic Programming', 'Prefix Sum']
0
stone-game-v
DP Javascript
dp-javascript-by-rockwell153-kjaf
\n/**\n:subproblem\n what is the maximum score of the rest of the stones\n\n:recurrence\n for all possible break points\n if equal halfs\n
rockwell153
NORMAL
2020-08-23T18:04:55.021498+00:00
2020-08-23T18:05:04.633135+00:00
113
false
```\n/**\n:subproblem\n what is the maximum score of the rest of the stones\n\n:recurrence\n for all possible break points\n if equal halfs\n dp[left][right] = max(\n leftsum + recur( left ),\n rightsum + recur( right )\n )\n else \n dp[left][right] = max( dp, recur( min( left, right ) ) )\n \n return dp[left][right]\n */\nvar stoneGameV = function(a) {\n const rowSum = getRowSumWithNums( a )\n const dp = Array.from({length:a.length+1},_=>Array(a.length+1).fill(0))\n const guess = ( left, right ) => {\n if ( left === right ) return 0\n if ( dp[ left ][ right ] ) return dp[ left ][ right ]\n\n for ( let i = left + 1; i <= right; i++ ) {\n const leftSum = rowSum( left, i - 1 )\n const rightSum = rowSum( i, right )\n\n if ( leftSum === rightSum ) {\n dp[ left ][ right ] = Math.max(\n dp[ left ][ right ],\n leftSum + guess( left, i - 1 ),\n rightSum + guess( i, right )\n )\n } else if ( rightSum > leftSum ) {\n dp[ left ][ right ] = Math.max(\n dp[ left ][ right ],\n leftSum + guess( left, i - 1 )\n )\n } else {\n dp[ left ][ right ] = Math.max(\n dp[ left ][ right ],\n rightSum + guess( i, right )\n )\n }\n }\n \n return dp[ left ][ right ]\n }\n guess( 0, a.length-1 )\n \n return dp[ 0 ][ a.length-1 ]\n}\n\nconst getRowSumWithNums = nums => {\n const sums = nums.reduce( ( s, x ) => [ ...s, x + ( s[s.length - 1 ] || 0 ) ], [] )\n\n return ( left, right ) => sums[ right ] - ( sums[ left - 1 ] || 0 )\n}\n```
1
0
['Dynamic Programming', 'JavaScript']
0
stone-game-v
C# Prefix Sum + Memoization
c-prefix-sum-memoization-by-ve7545-uz17
Runtime: 228 ms\nMemory Usage: 33.7 MB\n\n public int StoneGameV(int[] stoneValue) {\n int[,] dp = new int[stoneValue.Length, stoneValue.Length];
ve7545
NORMAL
2020-08-23T15:43:23.240503+00:00
2020-08-23T15:57:00.697791+00:00
77
false
Runtime: 228 ms\nMemory Usage: 33.7 MB\n```\n public int StoneGameV(int[] stoneValue) {\n int[,] dp = new int[stoneValue.Length, stoneValue.Length]; \n int[] prefixSum = new int[stoneValue.Length+1];\n \n for(int i=0; i< stoneValue.Length; i++)\n {\n prefixSum[i+1] = prefixSum[i] + stoneValue[i];\n }\n \n return Traverse(stoneValue, 0, stoneValue.Length-1, dp, prefixSum);\n }\n \n private int Traverse(int[] stoneValue, int start, int end, int[,] dp, int[] prefixSum)\n { \n if (start >= end) { return 0; }\n if (dp[start,end] != 0) { return (dp[start,end]==-1)? 0 : dp[start,end]; }\n \n int total = prefixSum[end+1] - prefixSum[start];\n \n int left =0;\n int right;\n int result = -1;\n \n for(int i=start; i < end; i++)\n {\n left = prefixSum[i+1] - prefixSum[start];\n right = total - left;\n \n if (left >= right)\n {\n result = Math.Max(result, right + Traverse(stoneValue, i+1, end, dp, prefixSum));\n }\n \n if (left <= right)\n {\n result = Math.Max(result, left + Traverse(stoneValue, start, i, dp, prefixSum));\n }\n }\n \n dp[start, end] = result;\n return result;\n }\n```\n\nSecond way of doing this but it takes much longer to execute:\n\nRuntime: 1328 ms\nMemory Usage: 33.5 MB\n```\n\n public int StoneGameV(int[] stoneValue) {\n int[,] dp = new int[stoneValue.Length, stoneValue.Length];\n \n int[] prefixSum = new int[stoneValue.Length+1];\n \n for(int i=0; i< stoneValue.Length; i++)\n {\n dp[i,i] = 0;\n prefixSum[i+1] = prefixSum[i] + stoneValue[i];\n }\n \n for(int k=1; k< stoneValue.Length; k++)\n {\n for(int i=0; i + k < stoneValue.Length; i++)\n {\n Traverse(stoneValue, i, i+k, dp, prefixSum);\n }\n }\n \n return dp[0, stoneValue.Length-1];\n }\n \n private int Traverse(int[] stoneValue, int start, int end, int[,] dp, int[] prefixSum)\n { \n int total = prefixSum[end+1] - prefixSum[start];\n \n int left =0;\n int right;\n int result = 0;\n \n for(int i=start; i < end; i++)\n {\n left = prefixSum[i+1] - prefixSum[start];\n right = total - left;\n \n if (left >= right)\n {\n result = Math.Max(result, right + dp[i+1,end]);\n }\n \n if (left <= right)\n {\n result = Math.Max(result, left + dp[start, i]);\n }\n }\n \n dp[start, end] = result;\n return result;\n }
1
0
[]
1
stone-game-v
please clear my doubt
please-clear-my-doubt-by-anshuman2043-bwbr
\nclass Solution:\n def stoneGameV(self, stoneValue: List[int]) -> int:\n ans = 0\n def game(l,score):\n #print(l)\n #pri
Anshuman2043
NORMAL
2020-08-23T09:06:05.966531+00:00
2020-08-23T09:06:05.966562+00:00
136
false
```\nclass Solution:\n def stoneGameV(self, stoneValue: List[int]) -> int:\n ans = 0\n def game(l,score):\n #print(l)\n #print(score)\n if len(l) <= 1:\n nonlocal ans\n ans = max((ans,score))\n return\n s = sum(l)\n x = 0\n for i in range(len(l)):\n x += l[i]\n if x == s/2:\n game(l[:i+1],score+x)\n game(l[i+1:],score+x)\n return\n elif x >s/2:\n game(l[i+1:],score+s-x)\n game(l[:i],score+x-l[i])\n return \n game(stoneValue,0)\n return ans\n \n```\n\nhere is my greedy approch for this Question.\nmy approch is as follow \n\n1. i first find the element, that add to either side of the array gives the sum greater than or equal to half of the sum of initial array.\n2. then there are two path now , either we choose first half or we choose second half .\n3. we compare the result for each such possiblity and return maximum of them \n\nmy ans for arr = [98 ,77 ,24 ,49 ,6 ,12 ,2 ,44 ,51 ,96] is 307\nbut expected ans is 330\n\nis have checked my ans many times but i can\'t find any way to get the ans (score) 330.\ni thought ans is wrong\ncan you help me out how the ans is 330.\n
1
0
[]
1
stone-game-v
TopDownDFS+Memo(O(N^3)) And BottomUpDP(O(N^2))
topdowndfsmemoon3-and-bottomupdpon2-by-j-xomg
Top Down DFS + Memo 460ms\ncpp\nclass Solution {\n vector<int> prefixSum;\n vector<vector<int>> mem;\n int cnt = 0;\n void dfs(const vector<int>& pr
jiah
NORMAL
2020-08-23T08:05:35.198352+00:00
2020-08-23T08:09:33.253435+00:00
123
false
Top Down DFS + Memo 460ms\n```cpp\nclass Solution {\n vector<int> prefixSum;\n vector<vector<int>> mem;\n int cnt = 0;\n void dfs(const vector<int>& prefixSum, int begin, int end) {\n if (mem[begin][end])\n return;\n if (begin+1 == end)\n return;\n cnt ++;\n int ans = 0;\n int total = prefixSum[end] - prefixSum[begin];\n if (end - begin >= 2) {\n for (int mid = begin+1; mid < end; mid++) {\n int left = prefixSum[mid] - prefixSum[begin];\n int right = total - left;\n int tmp = 0;\n if (left < right) {\n tmp += left;\n dfs(prefixSum, begin, mid);\n tmp += mem[begin][mid];\n } else if (left > right) {\n tmp += right;\n dfs(prefixSum, mid, end);\n tmp += mem[mid][end];\n } else {\n tmp += left;\n dfs(prefixSum, begin, mid);\n dfs(prefixSum, mid, end);\n tmp += max(mem[begin][mid], mem[mid][end]);\n }\n ans = max(ans, tmp);\n }\n } \n mem[begin][end] = ans;\n }\npublic:\n int stoneGameV(vector<int>& stoneValue) {\n cout << stoneValue.size() << endl;\n int n = stoneValue.size();\n prefixSum.resize(n+1);\n mem.resize(n+1, vector<int>(n+1));\n for (int i = 0; i < n; i++)\n prefixSum[i+1] = prefixSum[i] + stoneValue[i];\n dfs(prefixSum, 0, stoneValue.size());\n cout << cnt << endl; // See how many states visited if you want to know why O(n^3) topdown works\n return mem[0][n];\n }\n};\n```\n\nBottom Up DP 200+ms\n```cpp\nclass Solution {\npublic:\n int stoneGameV(vector<int>& stoneValue) {\n const int n = stoneValue.size();\n vector<int> ps(n+1); // prefix_sum\n vector<vector<int>> dp(n+1, vector<int>(n+1));\n vector<vector<int>> maxL = dp;\n vector<vector<int>> maxR = dp;\n vector<vector<int>> mid = dp;\n \n for (int i = 0; i < n; i++)\n ps[i+1] = ps[i] + stoneValue[i];\n \n for (int i = 0; i <= n; i++) {\n int middle = i+1;\n for (int j = i+2; j <= n; j++) {\n while (middle < j && \n ps[middle] - ps[i] <= ps[j] - ps[middle]) {\n middle ++;\n }\n mid[i][j] = middle-1;\n }\n }\n \n for (int i = 0; i < n; i++)\n maxL[i][i+1] = maxR[i][i+1] = stoneValue[i];\n \n for (int i = n; i >= 0; i--) {\n for (int j = i+2; j <= n; j++) {\n int middle = mid[i][j];\n if (ps[middle] - ps[i] < ps[j] - ps[middle]) {\n dp[i][j] = max(maxL[i][middle], maxR[middle+1][j]);\n } else {\n dp[i][j] = max(maxL[i][middle], maxR[middle][j]);\n }\n maxL[i][j] = max(maxL[i][j-1], dp[i][j] + ps[j] - ps[i]);\n maxR[i][j] = max(maxR[i+1][j], dp[i][j] + ps[j] - ps[i]);\n }\n }\n return dp[0][n];\n }\n};\n```\n\n
1
0
[]
0
stone-game-v
Prefix Sum +DP(Memoization)
prefix-sum-dpmemoization-by-ghoshashis54-db68
\nint cache[505][505];\nint pre[505];\nint n;\nint dp(int left,int right)\n{\n if(left == right)\n return 0;\n int &ans = cache[left][right];\n
ghoshashis545
NORMAL
2020-08-23T08:00:39.298549+00:00
2020-08-23T08:00:39.298593+00:00
102
false
```\nint cache[505][505];\nint pre[505];\nint n;\nint dp(int left,int right)\n{\n if(left == right)\n return 0;\n int &ans = cache[left][right];\n if(ans != -1)\n return ans;\n // left subarray -> [left , partition_index]\n // right subarray -> [partition_index + 1 , right]\n \n for(int partition_index = left ; partition_index < right; ++partition_index)\n {\n int leftsum = pre[partition_index];\n if(left > 0)\n leftsum -= pre[left-1];\n \n int rightsum = pre[right] - pre[partition_index];\n \n // if leftsum value greater than rightsum than bob throw away left subarray([left,partition_index]) and rightsum value will added to answer and do following step using right subarray([partition_index+1,right]).\n \n if(leftsum > rightsum)\n ans = max(ans, rightsum + dp(partition_index+1 , right));\n \n else if(leftsum < rightsum)\n ans = max(ans ,leftsum + dp(left , partition_index));\n // if leftsum equal to rightsum than we go both subarray seperately.\n else\n {\n ans = max(ans , rightsum + dp(partition_index+1 , right));\n ans = max(ans , leftsum + dp(left , partition_index));\n }\n }\n return ans;\n \n}\nclass Solution {\npublic:\n int stoneGameV(vector<int>& a) {\n n = a.size();\n // initialize\n for(int i = 0;i<n;++i)\n {\n for(int j =0;j<n;++j)\n cache[i][j]=-1;\n pre[i] =0;\n }\n\t\t// build prefix\n for(int i = 0;i < n;++i)\n {\n if(i > 0)\n pre[i]+=pre[i-1];\n pre[i]+=a[i];\n }\n \n return dp(0,n-1);\n \n }\n};\n```\nTime : O(n^3)\nSpace : O(n^2)
1
0
[]
2
stone-game-v
Python PrefixSum + DFS memo
python-prefixsum-dfs-memo-by-ysz951-7s79
\nclass Solution(object):\n def stoneGameV(self, stones):\n """\n :type stoneValue: List[int]\n :rtype: int\n """\n n = le
ysz951
NORMAL
2020-08-23T04:19:11.844616+00:00
2020-08-23T04:19:11.844650+00:00
96
false
```\nclass Solution(object):\n def stoneGameV(self, stones):\n """\n :type stoneValue: List[int]\n :rtype: int\n """\n n = len(stones)\n preSum = [0] * (n + 1)\n for i in range(1, n + 1):\n preSum[i] = stones[i - 1] + preSum[i - 1]\n memo = {}\n def dfs(s, e):\n if s == e: return 0\n if (s, e) in memo: return memo[(s, e)]\n res = -float(\'inf\')\n for i in range(s, e):\n option1 = preSum[i + 1] - preSum[s]\n option2 = preSum[e + 1] - preSum[i + 1]\n if option1 > option2:\n res = max(res, option2 + dfs(i + 1, e))\n elif option1 < option2:\n res = max(res, option1 + dfs(s, i))\n else:\n res = max(res, option1 + dfs(s, i), option2 + dfs(i + 1, e))\n memo[(s, e)] = res\n return res\n return dfs(0, n - 1)\n```
1
0
[]
0
stone-game-v
[Java] 45ms clean code, Top down dp O(n^3)
java-45ms-clean-code-top-down-dp-on3-by-6kuj3
Java\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] preSum = new int[n + 1];\n for (
binglelove
NORMAL
2020-08-23T04:11:47.131280+00:00
2020-08-23T04:11:47.131337+00:00
129
false
```Java\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] preSum = new int[n + 1];\n for (int i = 0; i < n; i++)\n preSum[i + 1] = preSum[i] + stoneValue[i];\n int[][] memo = new int[n][n];\n return dfs(stoneValue, preSum, 0, n - 1, memo);\n }\n \n private int dfs(int[] stone, int[] preSum, int left, int right, int[][] memo) {\n if (left >= right) return 0;\n if (left + 1 == right) return Math.min(stone[left], stone[right]);\n if (memo[left][right] != 0) return memo[left][right];\n \n int res = 0;\n for (int i = left; i <= right; i++) {\n int leftSum = preSum[i + 1] - preSum[left];\n int rightSum = preSum[right + 1] - preSum[i + 1];\n \n if (leftSum >= rightSum) res = Math.max(res, rightSum + dfs(stone, preSum, i + 1, right, memo));\n if (leftSum <= rightSum) res = Math.max(res, leftSum + dfs(stone, preSum, left, i, memo));\n }\n memo[left][right] = res;\n return res;\n }\n}\n```
1
1
[]
0
stone-game-v
Any idea how to speedup bottoms up DP ? | C++ | O(N^3) | TLE
any-idea-how-to-speedup-bottoms-up-dp-c-alf80
imo, dp questions should accept both top down and bottom up approaches. No able to figure out what I could have done to improve this solution. Suggestions are w
all_might
NORMAL
2020-08-23T04:05:42.285150+00:00
2020-08-23T04:11:08.659923+00:00
156
false
> imo, dp questions should accept both top down and bottom up approaches. No able to figure out what I could have done to improve this solution. Suggestions are welcome.\n\n```\nclass Solution {\npublic:\n typedef long long ll;\n int stoneGameV(vector<int>& sv) {\n int n = sv.size();\n vector<int> presum(n, 0);\n for (int i = 0; i<n; i++) presum[i] = sv[i] + ((i>0)?presum[i-1]:0);\n\n vector<vector<ll>> dp(n, vector<ll>(n, INT_MIN));\n\n for (int l = 0; l<n; l++) {\n for (int i = 0; i<(n-l); i++){ \n int j = i+l;\n if (i==j) dp[i][j] = 0;\n else if(i+1 == j) dp[i][j] = min(sv[i], sv[j]);\n else {\n ll &v = dp[i][j];\n for (int k = i+1; k<=j; k++) {\n int lsum = presum[k-1] - ((i>0)?presum[i-1]:0);\n int rsum = presum[j] - presum[k-1];\n\n if (rsum == lsum) v = max(dp[i][k-1],dp[k][j]) + lsum;\n else if (lsum > rsum) v = max(v, rsum + dp[k][j]);\n else v = max(v, lsum + dp[i][k-1]);\n }\n }\n }\n }\n\n return dp[0][n-1];\n }\n};\n```
1
0
[]
2
stone-game-v
C++ DP | Easy Solution | Memoization
c-dp-easy-solution-memoization-by-kaintp-ydam
class Solution {\npublic:\n \n \n int findMax(vector&prefix, int start, int end, vector>&dp ){\n \n if(start==end){\n return 0
kaint
NORMAL
2020-08-23T04:05:40.851553+00:00
2020-08-23T04:09:10.862069+00:00
95
false
class Solution {\npublic:\n \n \n int findMax(vector<int>&prefix, int start, int end, vector<vector<int>>&dp ){\n \n if(start==end){\n return 0;\n } \n if(dp[start][end]!=-1)\n return dp[start][end];\n int maxans=0;\n \n for(int cut=start;cut<end;cut++){\n \n int leftRowSum=prefix[cut]-prefix[start-1];\n int rightRowSum=prefix[end]-prefix[cut];\n \n if(leftRowSum < rightRowSum ){\n maxans=max(maxans, leftRowSum+findMax(prefix, start, cut,dp));\n }else if(leftRowSum>rightRowSum){\n maxans=max(maxans, rightRowSum+findMax(prefix, cut+1, end,dp));\n }else{\n maxans=max(maxans, leftRowSum+findMax(prefix, start, cut, dp));\n maxans=max(maxans, rightRowSum+findMax(prefix, cut+1, end, dp));\n }\n }\n \n return dp[start][end]=maxans;\n }\n\n int stoneGameV(vector<int>& arr) {\n \n arr.insert(arr.begin(),0);\n vector<vector<int>>dp(502,vector<int>(502,-1));\n \n for(int i=2;i<arr.size();i++){\n arr[i]+=arr[i-1];\n } \n\t\t\n return findMax(arr, 1, arr.size()-1,dp);\n }\n};
1
0
[]
0
stone-game-v
[Java] Top Down DP with Memo O(N^3)
java-top-down-dp-with-memo-on3-by-yuhwu-vg24
\nclass Solution {\n int[][] memo;\n public int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] pSum = new int[n+1];\n
yuhwu
NORMAL
2020-08-23T04:02:17.321815+00:00
2020-08-23T04:02:17.321877+00:00
119
false
```\nclass Solution {\n int[][] memo;\n public int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length;\n int[] pSum = new int[n+1];\n memo = new int[n+1][n+1];\n for(int i=1; i<=n; i++){\n pSum[i] = pSum[i-1] + stoneValue[i-1];\n }\n return calc(pSum, 0, n-1);\n }\n \n public int calc(int[] pSum, int lo, int hi){\n if(lo>=hi){\n return 0;\n }\n if(memo[lo][hi]!=0){\n return memo[lo][hi];\n }\n int max = 0;\n for(int k=lo; k<hi; k++){\n int cur = 0;\n int left = pSum[k+1] - pSum[lo];\n int right = pSum[hi+1] - pSum[k+1];\n if(left>right){\n cur = right + calc(pSum, k+1, hi);\n }\n else if(left<right){\n cur = left + calc(pSum, lo, k);\n }\n else{\n cur = left + Math.max(calc(pSum, lo, k), calc(pSum, k+1, hi));\n }\n max = Math.max(max, cur);\n }\n memo[lo][hi] = max;\n return max;\n }\n}\n```
1
0
[]
0
stone-game-v
Easy To understand! JAVA DFS+Memory+preSum!!
easy-to-understand-java-dfsmemorypresum-8u3vh
I think it is clear to understand! Maybe someone can help me to explain it.\n\n\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n\n int
sugersu
NORMAL
2020-08-23T04:02:13.159504+00:00
2020-08-23T04:02:13.159572+00:00
112
false
I think it is clear to understand! Maybe someone can help me to explain it.\n\n```\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n\n int n=stoneValue.length;\n if(n<2) return 0;\n \n long[] preSum=new long[n+1];\n Map<Pair<Integer,Integer>,Long> memo= new HashMap<>();\n for(int i=1;i<=n;i++){\n preSum[i]=preSum[i-1]+stoneValue[i-1];\n }\n \n return (int)dfs(preSum,0,n,memo);\n \n }\n\n long dfs(long[] sum, int lo, int hi, Map<Pair<Integer,Integer>,Long> memo){\n //System.out.println(lo+","+hi);\n if(lo+1==hi) return 0;\n Pair<Integer,Integer> key = new Pair<>(lo,hi);\n \n if(memo.containsKey(key)) return memo.get(key);\n \n long ans=0;\n for(int i=lo+1;i<hi;i++){\n long left=sum[i]-sum[lo];\n long right=sum[hi]-sum[i];\n \n if(left>right){\n ans=Math.max(right+dfs(sum,i,hi,memo),ans);\n }else if(left < right){\n ans=Math.max(left+dfs(sum,lo,i,memo),ans);\n }else{\n ans=Math.max(left+Math.max(dfs(sum,i,hi,memo),dfs(sum,lo,i,memo)),ans);\n }\n }\n \n memo.put(key,ans);\n return ans;\n }\n}\n```
1
0
[]
0
stone-game-v
Top Down DP with Memoization
top-down-dp-with-memoization-by-zsshen-rh2l
\nclass Solution {\npublic:\n int stoneGameV(vector<int>& arr) {\n \n int n = arr.size();\n\n vector<int> prefix(n + 1, 0);\n for
zsshen
NORMAL
2020-08-23T04:02:02.827965+00:00
2020-08-23T04:02:02.828013+00:00
123
false
```\nclass Solution {\npublic:\n int stoneGameV(vector<int>& arr) {\n \n int n = arr.size();\n\n vector<int> prefix(n + 1, 0);\n for (int i = 1 ; i <= n ; ++i) {\n prefix[i] = prefix[i - 1] + arr[i - 1];\n }\n \n vector<vector<int>> dp(n, vector<int>(n, -1));\n return topDown(arr, 0, n - 1, prefix, dp);\n }\n \nprivate:\n int topDown(\n vector<int>& arr,\n int l, int r,\n vector<int>& prefix,\n vector<vector<int>>& dp) {\n \n if (l == r) {\n return 0;\n }\n \n if (dp[l][r] != -1) {\n return dp[l][r];\n }\n \n int opt = 0; \n for (int m = l ; m < r ; ++m) {\n int left = prefix[m + 1] - prefix[l];\n int right = prefix[r + 1] - prefix[m + 1];\n \n if (left > right) {\n int sum = right + topDown(arr, m + 1, r, prefix, dp);\n opt = max(opt, sum);\n } else if (left < right) {\n int sum = left + topDown(arr, l, m, prefix, dp);\n opt = max(opt, sum);\n } else {\n int sum = right + topDown(arr, m + 1, r, prefix, dp);\n opt = max(opt, sum);\n sum = left + topDown(arr, l, m, prefix, dp);\n opt = max(opt, sum); \n }\n }\n \n return dp[l][r] = opt;\n }\n};\n```
1
0
[]
0
stone-game-v
[Python3] intuitive DP
python3-intuitive-dp-by-xavier90-g0oq
\nclass Solution:\n def stoneGameV(self, stoneValue: List[int]) -> int:\n n = len(stoneValue)\n \n pre = [0]\n for e in stoneValue:\n
xavier90
NORMAL
2020-08-23T04:01:33.439148+00:00
2020-08-27T23:54:09.155057+00:00
172
false
```\nclass Solution:\n def stoneGameV(self, stoneValue: List[int]) -> int:\n n = len(stoneValue)\n \n pre = [0]\n for e in stoneValue:\n pre.append(pre[-1]+e)\n \n import functools\n @functools.lru_cache(None)\n def dp(i, j):\n if i >= j:\n return 0\n res = 0\n for mid in range(i, j):\n\t\t\t\tleft = pre[mid+1]-pre[i]\n\t\t\t\tright = pre[j+1]-pre[mid+1]\n if right < left:\n res = max(res, dp(mid+1,j)+right)\n elif right > left:\n res = max(res, dp(i, mid)+left)\n else:\n res = max(res, dp(i, mid)+left, dp(mid+1,j)+right)\n return res\n return dp(0,n-1)\n```
1
1
[]
0
stone-game-v
[Java] Simple top-down dfs+memo(with comments)
java-simple-top-down-dfsmemowith-comment-0rki
Intuition\nSimulate the game by dividing the array into two subarrays at each iteration. Add the subarray with smaller sum to result of current search and conti
dorayaki1018
NORMAL
2020-08-23T04:01:30.858769+00:00
2020-08-23T04:22:01.977688+00:00
161
false
**Intuition**\nSimulate the game by dividing the array into two subarrays at each iteration. Add the subarray with smaller sum to result of current search and continue searching the subarray with smaller sum.\n\n`dp[i][j]` represents the max score we can get in range `[i, j]`\n\nWe use the `presum` array to comput the subarray sum in `O(1)`\n\n```java\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n int n = stoneValue.length, sum = 0;;\n Integer[][] dp = new Integer[n][n];\n // initialize presum array\n int[] presum = new int[n];\n for(int i = 0; i < n; i++) {\n sum += stoneValue[i];\n presum[i] = sum;\n }\n return dfs(dp, 0, n-1, presum, stoneValue);\n }\n \n private int dfs(Integer[][] dp, int start, int end, int[] presum, int[] stoneValue) {\n // base condition\n // when start == end, we already added the value in previous function all. \n if(start == end) {\n return 0;\n }\n // return if we already searched this range\n if(dp[start][end] != null) return dp[start][end];\n int res = 0;\n \n // left: [start, i]\n // right: (i, end]\n for(int i = start; i < end; i++) {\n int left = presum[i] - (start > 0 ? presum[start - 1] : 0);\n int right = presum[end] - presum[i];\n // add the smaller pile to current result and continue search on the smaller pile\n if(left > right) {\n res = Math.max(res, right + dfs(dp, i + 1, end, presum, stoneValue));\n } else if(left < right) {\n res = Math.max(res, left + dfs(dp, start, i, presum, stoneValue));\n } else {\n res = Math.max(res, right + dfs(dp, i + 1, end, presum, stoneValue));\n res = Math.max(res, left + dfs(dp, start, i, presum, stoneValue));\n }\n }\n return dp[start][end] = res;\n }\n}\n```\n\nTime: O(n<sup>3</sup>)\n\nSpace: O(n<sup>2</sup>)\n
1
0
[]
0
stone-game-v
[C++] Prefix Sum + DP (Memoization)
c-prefix-sum-dp-memoization-by-jayesh_jo-70tw
Complexity Time complexity: O(n³) Space complexity: O(n²) Code
Jayesh_Joshi
NORMAL
2025-04-05T13:17:14.353885+00:00
2025-04-05T13:17:14.353885+00:00
1
false
# Complexity - Time complexity: O(n³) <!-- Add your time complexity here, e.g. $$O(n)$$ --> - Space complexity: O(n²) <!-- Add your space complexity here, e.g. $$O(n)$$ --> # Code ```cpp [] class Solution { public: int n; vector<int> v, p; vector<vector<int>> dp; int solve(int l, int r) { if (l >= r) return 0; int ans = 0; if (dp[l][r] != -1) { return dp[l][r]; } for (int k = l; k <= r; k++) { int left = p[k]; if (l != 0) { left -= p[l - 1]; } int right = p[r] - p[k]; int cnt = 0; if (left > right) { cnt = right + solve(k + 1, r); } else if (right > left) { cnt = left + solve(l, k); } else { cnt = left + max(solve(l, k), solve(k + 1, r)); } ans = max(ans, cnt); } return dp[l][r] = ans; } int stoneGameV(vector<int>& stoneValue) { v = stoneValue; n = v.size(); p.assign(n, 0); p[0] = v[0]; for (int i = 1; i < n; i++) { p[i] = p[i - 1] + v[i]; } dp.assign(n + 1, vector<int>(n + 1, -1)); return solve(0, n - 1); } }; ```
0
0
['C++']
0
stone-game-v
Simple|| DP || Memoization Code ||
simple-dp-memoization-code-by-rwt2003-gida
IntuitionApproachComplexity Time complexity: O(n^3) Space complexity: O(n^2)Code
rwt2003
NORMAL
2025-03-08T10:29:05.915101+00:00
2025-03-08T10:29:05.915101+00:00
2
false
# Intuition <!-- Describe your first thoughts on how to solve this problem. --> # Approach <!-- Describe your approach to solving the problem. --> # Complexity - Time complexity: <!-- Add your time complexity here, e.g. $$O(n)$$ --> O(n^3) - Space complexity: <!-- Add your space complexity here, e.g. $$O(n)$$ --> O(n^2) # Code ```cpp [] class Solution { public: int n; int dp[505][505]; int rec(int i,int j,vector<int> &p){ //base case if(i >= j)return 0; //here we have to divide the v[i,....j]; if(dp[i][j] != -1)return dp[i][j]; int mx = INT_MIN; for(int k = i;k<j;k++){ int leftSum = (i != 0) ? p[k] - p[i-1] : p[k]; int rightSum = p[j] - p[k]; if(rightSum > leftSum){ mx = max(mx,rec(i,k,p) + leftSum); }else if(leftSum > rightSum){ mx = max(mx,rec(k+1,j,p) + rightSum); }else{ mx = max(mx,rec(i,k,p) + leftSum); mx = max(mx,rec(k+1,j,p) + rightSum); } } return dp[i][j] = mx; } int stoneGameV(vector<int>& v) { n = v.size(); memset(dp,-1,sizeof(dp)); vector<int> preSum(n,0); preSum[0] = v[0]; for(int i=1;i<n;i++){ preSum[i] = preSum[i-1] + v[i]; } return rec(0,n-1,preSum); } }; ```
0
0
['C++']
0
stone-game-v
Easy CPP Solution
easy-cpp-solution-by-vidhyarthisunav-ors4
Code
vidhyarthisunav
NORMAL
2025-03-04T17:56:15.791401+00:00
2025-03-04T17:56:15.791401+00:00
5
false
# Code ```cpp [] class Solution { public: vector<int> prefix_sum; int dp[501][501]; int dfs(int i, int j) { if (i == j) return 0; if (dp[i][j] != -1) return dp[i][j]; int res = 0; for (int idx = i; idx < j; idx++) { int left_sum = prefix_sum[idx + 1] - prefix_sum[i]; int right_sum = prefix_sum[j + 1] - prefix_sum[idx + 1]; if (left_sum < right_sum) { res = max(res, left_sum + dfs(i, idx)); } else if (left_sum > right_sum) { res = max(res, right_sum + dfs(idx + 1, j)); } else { res = max(res, max(left_sum + dfs(i, idx), right_sum + dfs(idx + 1, j))); } } return dp[i][j] = res; } int stoneGameV(vector<int>& stoneValue) { int n = stoneValue.size(); prefix_sum.resize(n + 1, 0); memset(dp, -1, sizeof(dp)); for (int i = 0; i < n; i++) { prefix_sum[i + 1] = prefix_sum[i] + stoneValue[i]; } return dfs(0, n - 1); } }; ```
0
0
['C++']
0
stone-game-v
✅ C++ sol. using TOP DOWN (RECURSIVE) 2-d DP and PREFIX-SUM
c-sol-using-top-down-recursive-2-d-dp-an-vf43
Code
deepanshugupta134
NORMAL
2025-02-19T18:48:13.557923+00:00
2025-02-19T18:48:13.557923+00:00
6
false
# Code ```cpp [] class Solution { public: int dp[501][501]; int fun(vector<int>&v , vector<int>&ps , int l , int r ){ if(r - l == 0){ return 0 ; } if(dp[l][r] != -1){ return dp[l][r]; } int ans = 0 ; int lp = 0 , rp = 0 ; for(int i=l ; i<r ; i++){ lp = ps[i] - ((l==0)? 0 : ps[l-1]); rp = ps[r] - ps[i] ; if(rp == lp){ ans = max(lp + fun(v , ps , l , i) , rp + fun(v , ps , i+1 , r )); } else if(lp > rp){ ans = max(ans , rp + fun(v , ps , i+1 , r )); } else{ ans = max(ans , lp + fun(v , ps , l , i)); } } return dp[l][r] = ans ; } int stoneGameV(vector<int>& stoneValue) { memset(dp , -1 , sizeof(dp)); int n = stoneValue.size(); vector<int>v(n); v[0] = stoneValue[0]; for(int i=1 ; i<n ; i++){ v[i] = v[i-1] + stoneValue[i]; } return fun(stoneValue , v , 0 , n-1 ); } }; ```
0
0
['Array', 'Dynamic Programming', 'Recursion', 'Memoization', 'Game Theory', 'C++']
0
stone-game-v
Bottom up DP with Knuth optimization
bottom-up-dp-with-knuth-optimization-by-hflwb
ApproachBottom up DP with Knuth optimization.Sorry in Japanese, but refer tomy blog postfor the idea.Complexity Time complexity:O(N^2) Space complexity:O(N^2)
kudojp
NORMAL
2025-02-18T09:27:28.795886+00:00
2025-02-18T09:29:18.085076+00:00
6
false
# Approach Bottom up DP with Knuth optimization. Sorry in Japanese, but refer to [my blog post](https://qiita.com/kudojp/items/5811b6d6444c866780a5) for the idea. # Complexity - Time complexity: `O(N^2)` <!-- Add your time complexity here, e.g. $$O(n)$$ --> - Space complexity: `O(N^2)` <!-- Add your space complexity here, e.g. $$O(n)$$ --> # Code ```python3 [] class Solution: def stoneGameV(self, stones: List[int]) -> int: n = len(stones) self.stones = stones self.prefix_sum = self.build_prefix_sum(stones) dp = [[None] * n for _ in range(n)] best_cut = [[None] * n for _ in range(n)] for i in range(n): dp[i][i] = 0 best_cut[i][i] = i # I am not sure if this is really okay. for right in range(1, n): left = 0 # fill in cells in this order: # (r, c) -> (r+1, c+1) -> (r+2, c+2) -> ... while 0 <= left <= n-1 and 0 <= right <= n-1: max_score = - math.inf mid_then = None # In case of tie, any of mid is fine? # knuth optimization for mid in range(best_cut[left][right-1] - 1, best_cut[left+1][right] + 1 + 1): if not left <= mid <= right - 1: continue left_sum = self.value_sum(left, mid) right_sum = self.value_sum(mid+1, right) if left_sum == right_sum: score = max(dp[left][mid] + left_sum, dp[mid+1][right] + right_sum) elif left_sum < right_sum: score = dp[left][mid] + left_sum else: score = dp[mid+1][right] + right_sum if max_score < score: max_score = score mid_then = mid dp[left][right] = max_score best_cut[left][right] = mid_then left += 1 right += 1 return dp[0][n-1] def build_prefix_sum(self, arr): curr_sum = 0 ret = [] for num in arr: curr_sum += num ret.append(curr_sum) return ret @cache def value_sum(self, left, right): if left == 0: return self.prefix_sum[right] return self.prefix_sum[right] - self.prefix_sum[left - 1] ```
0
0
['Python3']
0
stone-game-v
Solution using Prefix sum and DP
solution-using-prefix-sum-and-dp-by-user-47qv
IntuitionApproachComplexity Time complexity: Space complexity: Code
user5947v
NORMAL
2025-01-30T09:03:49.144909+00:00
2025-01-30T09:03:49.144909+00:00
2
false
# Intuition <!-- Describe your first thoughts on how to solve this problem. --> # Approach <!-- Describe your approach to solving the problem. --> # Complexity - Time complexity: <!-- Add your time complexity here, e.g. $$O(n)$$ --> - Space complexity: <!-- Add your space complexity here, e.g. $$O(n)$$ --> # Code ```cpp [] class Solution { int _stoneGameV(vector<int>& stoneValue, vector<vector<int>>& dp, vector<int>& prefSum, int l, int r) { if(l==r) { return dp[l][r] = 0; } if(dp[l][r]!=-1) return dp[l][r]; int max_ans = 0; for(int i=l+1;i<r;i++) { int leftSum = prefSum[i]-prefSum[l]; int rightSum = prefSum[r] - prefSum[i]; int ans = 0; if(leftSum < rightSum) ans = _stoneGameV(stoneValue, dp, prefSum, l, i) + leftSum; else if(leftSum > rightSum) ans = _stoneGameV(stoneValue, dp, prefSum, i, r) + rightSum; else { ans = max(_stoneGameV(stoneValue, dp, prefSum, l, i)+leftSum, _stoneGameV(stoneValue, dp, prefSum, i, r)+rightSum); } max_ans = max(max_ans, ans); } return dp[l][r] = max_ans; } public: int stoneGameV(vector<int>& stoneValue) { int n = stoneValue.size(); vector<vector<int>> dp(n+1, vector<int>(n+1, -1)); vector<int> prefSum(n+1, 0); for(int i=1;i<=n;i++) { prefSum[i] = (i==0 ? 0 : prefSum[i-1]) + stoneValue[i-1]; } return _stoneGameV(stoneValue, dp, prefSum, 0, n); } }; ```
0
0
['C++']
0
stone-game-v
1563. Stone Game V
1563-stone-game-v-by-g8xd0qpqty-ii15
IntuitionApproachComplexity Time complexity: Space complexity: Code
G8xd0QPqTy
NORMAL
2025-01-13T16:24:20.719004+00:00
2025-01-13T16:24:20.719004+00:00
4
false
# Intuition <!-- Describe your first thoughts on how to solve this problem. --> # Approach <!-- Describe your approach to solving the problem. --> # Complexity - Time complexity: <!-- Add your time complexity here, e.g. $$O(n)$$ --> - Space complexity: <!-- Add your space complexity here, e.g. $$O(n)$$ --> # Code ```cpp [] class Solution { public: int stoneGameV(vector<int>& stoneValue) { int n = stoneValue.size(); vector<int> prefixSum(n + 1, 0); vector<vector<int>> dp(n, vector<int>(n, 0)); for (int i = 1; i <= n; ++i) { prefixSum[i] = prefixSum[i - 1] + stoneValue[i - 1]; } for (int len = 2; len <= n; ++len) { for (int left = 0; left + len - 1 < n; ++left) { int right = left + len - 1; for (int mid = left; mid < right; ++mid) { int leftSum = prefixSum[mid + 1] - prefixSum[left]; int rightSum = prefixSum[right + 1] - prefixSum[mid + 1]; if (leftSum > rightSum) { dp[left][right] = max(dp[left][right], rightSum + dp[mid + 1][right]); } else if (rightSum > leftSum) { dp[left][right] = max(dp[left][right], leftSum + dp[left][mid]); } else { dp[left][right] = max(dp[left][right], max(leftSum + dp[left][mid], rightSum + dp[mid + 1][right])); } } } } return dp[0][n - 1]; } }; ```
0
0
['C++']
0
stone-game-v
Why this problem pass all cases in cpp but not in python3.
why-this-problem-pass-all-cases-in-cpp-b-ixei
Code
bepriyansh
NORMAL
2025-01-02T13:24:42.378145+00:00
2025-01-02T13:24:42.378145+00:00
4
false
# Code ```cpp [] class Solution { vector<int> sv, pre; vector<vector<int>> cache; int n; int gs(int l, int r) { return pre[r] - (l > 0 ? pre[l - 1] : 0); } int dp(int l, int r) { if (l == r) return 0; if (cache[l][r] != -1) return cache[l][r]; int res = 0; for (int i = l + 1; i <= r; i++) { int ls = gs(l, i - 1), rs = gs(i, r); if (ls <= rs) { res = max(res, ls + dp(l, i - 1)); } if (ls >= rs) { res = max(res, rs + dp(i, r)); } } return cache[l][r] = res; } public: int stoneGameV(vector<int>& _sv) { this->sv = _sv; n = size(sv); pre.resize(n, 0); cache = vector<vector<int>>(n+1, vector<int>(n+1, -1)); pre[0] = sv[0]; for (int i = 1; i < n; i++) { pre[i] = pre[i - 1] + sv[i]; } return dp(0, n - 1); } }; ``` ```python3 [] class Solution: def stoneGameV(self, sv: List[int]) -> int: n = len(sv) pre = [0] * n pre[0] = sv[0] for i in range(1, n): pre[i] = sv[i] + pre[i - 1] def gs(l, r): return pre[r] - (pre[l - 1] if l > 0 else 0) @cache def dp(l, r): if l == r: return 0 res = 0 for i in range(l + 1, r + 1): ls, rs = gs(l, i - 1), gs(i, r) if ls <= rs: res = max(res, ls + dp(l, i - 1)) if ls >= rs: res = max(res, rs + dp(i, r)) return res return dp(0, n - 1) ```
0
0
['C++']
0
stone-game-v
Dynamic Programming with Prefix Sum - O(N^3) - C++
dynamic-programming-with-prefix-sum-on3-et2p5
Intuition The problem is about maximizing a score obtained by choosing optimal subarrays in a sequence. The recursive nature of evaluating subarrays makes it co
upperknoot
NORMAL
2024-11-19T22:12:05.903644+00:00
2024-11-19T22:12:05.903679+00:00
6
false
# Intuition The problem is about maximizing a score obtained by choosing optimal subarrays in a sequence. The recursive nature of evaluating subarrays makes it conducive to a dynamic programming approach. We can utilize prefix sums to efficiently compute the sum of any subarray, which is a key operation in the solution. # Approach The approach involves using dynamic programming to solve subproblems of choosing the best scoring strategy for subarrays. We use prefix sums to quickly calculate subarray sums and a memoization table to store results of subproblems to avoid redundant calculations. 1. **Initialize Prefix Sum Array**: - We create a prefix sum array to store cumulative sums of the stone values. This allows us to compute the sum of any subarray in constant time by subtracting two prefix sums. 2. **Define Recursive Function with Memoization**: - We define a recursive function `solve(i, j)` that returns the maximum score obtainable from the subarray starting at index $i$ and ending at index $j$. The function uses a memoization table `dp` to store results of previously computed subproblems. 3. **Iterate Over Possible Partitions**: - For each subarray defined by indices $i$ and $j$, we iterate over possible partition points $k$. For each partition, we compute the sum of the left and right subarrays using the prefix sum array. 4. **Calculate Maximum Score**: - Depending on the sums of the left and right subarrays, we recursively compute the scores for the remaining subarrays and determine the maximum score possible. If the sums are equal, we consider both possible partitions. 5. **Store and Return Result**: - The result for each subarray is stored in the `dp` table, and the function returns the result, ensuring subproblems are solved only once. # Complexity - Time complexity: O(n^3) - The outer function `stoneGameV` initializes a prefix sum array and calls `solve(0, n-1)`, which is $O(n)$ for initialization. - The recursive function `solve(i, j)` iterates over $k$ from $i$ to $j-1$, leading to $O(n)$ iterations. - For each $k$, we perform constant time operations and recursive calls, leading to a total of $O(n^2)$ recursive subproblems. - Each subproblem involves iterating up to $n$ times, resulting in $O(n^3)$ overall complexity. - Memory complexity: O(n^2) - The space complexity is dominated by the `dp` table, which stores the results for each subarray $(i, j)$. This requires $O(n^2)$ space. - The prefix sum array uses $O(n)$ space, but this is overshadowed by the $dp$ table size. # Code ```cpp class Solution { public: int stoneGameV(vector<int>& stoneValue) { int n = stoneValue.size(); vector<vector<int>> dp(n, vector<int>(n, -1)); vector<int> prefix(n + 1, 0); for (int i = 0; i < n; i++) { prefix[i + 1] = prefix[i] + stoneValue[i]; } return solve(0, n - 1, stoneValue, prefix, dp); } int solve(int i, int j, vector<int>& stoneValue, vector<int>& prefix, vector<vector<int>>& dp) { if (i == j) return 0; if (dp[i][j] != -1) return dp[i][j]; int res = 0; for (int k = i; k < j; k++) { int left = prefix[k + 1] - prefix[i]; int right = prefix[j + 1] - prefix[k + 1]; if (left > right) { // discard left side res = max(res, right + solve(k + 1, j, stoneValue, prefix, dp)); } else if (left < right) { // discard right side res = max(res, left + solve(i, k, stoneValue, prefix, dp)); } else { // let alice choose the better side res = max( left + solve(i, k, stoneValue, prefix, dp), right + solve(k + 1, j, stoneValue, prefix, dp) ); } } return dp[i][j] = res; } }; ```
0
0
['Dynamic Programming', 'Prefix Sum', 'C++']
0
stone-game-v
Swift with recursion + caching.
swift-with-recursion-caching-by-wenjiema-iiwo
Intuition\nThe problem can be solved with recursion. Two helper functions each represent Alice and Bob, they both return Alice\'s sum:\n1. Alice would devide ar
wenjiema
NORMAL
2024-11-08T20:58:41.073531+00:00
2024-11-08T20:58:41.073552+00:00
1
false
# Intuition\nThe problem can be solved with recursion. Two helper functions each represent Alice and Bob, they both return Alice\'s sum:\n1. Alice would devide array into two parts, and find the division that returns biggest result.\n2. Bob would throw away array with the bigger sum, then add the smaller sum to Alice\'s sum and give back alice the array; When their sum equal, Bob will let alice decide which one to pick (the larger result). \n\nOnce the recursion solution is in place, caching can be added easily to bring down time complexity to O(n^2) \n\n# Complexity\n- Time complexity:\nO(n^2)\n\n- Space complexity:\nO(n^2)\n\n# Code\n```swift []\nclass Solution {\n var sumVal: [[Int]] = []\n\n func stoneGameV(_ stoneValue: [Int]) -> Int {\n sumVal = Array(repeating: Array(repeating: 0, count: stoneValue.count), count: stoneValue.count)\n for i in 0..<stoneValue.count {\n for j in i..<stoneValue.count {\n if i == j {\n sumVal[i][j] = stoneValue[i]\n } else {\n sumVal[i][j] = stoneValue[j] + sumVal[i][j-1]\n }\n }\n }\n\n var c = Array(repeating: Array(repeating: -1, count: stoneValue.count), count: stoneValue.count)\n\n return alice(stoneValue, 0, stoneValue.count-1, &c)\n }\n\n func alice(_ stoneValue: [Int], _ i: Int, _ j: Int, _ c: inout [[Int]]) -> Int {\n if i == j {\n return 0\n }\n\n if c[i][j] != -1 {\n return c[i][j]\n }\n\n var res = 0\n for k in i...j-1 {\n res = max(res, bob(stoneValue, i, k, j, &c))\n }\n c[i][j] = res\n return res\n }\n\n func bob(_ stoneValue: [Int], _ i: Int, _ j: Int, _ k: Int, _ c: inout [[Int]]) -> Int {\n let s1 = sumVal[i][j]\n let s2 = sumVal[j+1][k]\n\n if s1 > s2 {\n return alice(stoneValue, j+1, k, &c) + s2\n } else if s1 < s2 {\n return alice(stoneValue, i,j, &c) + s1\n } else {\n return max(alice(stoneValue, j+1, k, &c) + s2, alice(stoneValue, i,j, &c) + s1)\n }\n }\n}\n```
0
0
['Swift']
0
stone-game-v
My java 287ms solution 33% faster
my-java-287ms-solution-33-faster-by-ragh-ut4r
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time
raghavrathore7415
NORMAL
2024-10-27T05:07:38.217977+00:00
2024-10-27T05:07:38.217999+00:00
3
false
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```java []\nclass Solution {\n public int stoneGameV(int[] stoneValue) {\n int[] psum = new int[stoneValue.length];\n psum[0] = stoneValue[0];\n for(int i = 1; i < psum.length; i++){\n psum[i] = stoneValue[i] + psum[i - 1];\n }\n return getMax(0, stoneValue.length - 1, stoneValue, psum, new Integer[psum.length][psum.length]);\n }\n // 1 2 3 4 5 6 7 8\n public int getMax(int low, int high, int[] arr, int[] psum, Integer[][] cache){\n if(low == high){\n return 0;\n }\n if(cache[low][high] != null){\n return cache[low][high];\n }\n int res = 0;\n for(int i = low; i < high; i++){\n int lsum = low > 0 ? psum[i] - psum[low - 1] : psum[i];\n int hsum = psum[high] - psum[i];\n if(lsum > hsum){\n res = Math.max(res, hsum + getMax(i + 1, high, arr, psum, cache));\n }else if(lsum < hsum){\n res = Math.max(res, lsum + getMax(low, i, arr, psum, cache));\n }else{\n res = Math.max(res, hsum + getMax(i + 1, high, arr, psum, cache));\n res = Math.max(res, lsum + getMax(low, i, arr, psum, cache));\n }\n }\n return cache[low][high] = res;\n }\n}\n```
0
0
['Java']
0
stone-game-v
[Accepted] Swift
accepted-swift-by-vasilisiniak-9arq
\nclass Solution {\n func stoneGameV(_ stoneValue: [Int]) -> Int {\n\n let sum = stoneValue.reduce(into: [0]) { $0.append($0.last! + $1) }\n \n
vasilisiniak
NORMAL
2024-10-07T09:53:44.373752+00:00
2024-10-07T09:53:44.373785+00:00
0
false
```\nclass Solution {\n func stoneGameV(_ stoneValue: [Int]) -> Int {\n\n let sum = stoneValue.reduce(into: [0]) { $0.append($0.last! + $1) }\n \n var dp = Array(\n repeating: Array(repeating: 0, count: stoneValue.count),\n count: stoneValue.count\n )\n\n for r in 1..<stoneValue.count {\n for l in (0..<r).reversed() {\n \n for m in l..<r {\n let sl = sum[m + 1] - sum[l]\n let sr = sum[r + 1] - sum[m + 1]\n\n if sl <= sr {\n dp[l][r] = max(dp[l][r], sl + dp[l][m])\n }\n if sl >= sr {\n dp[l][r] = max(dp[l][r], sr + dp[m + 1][r])\n }\n }\n }\n }\n\n return dp[0][stoneValue.count - 1]\n }\n}\n```
0
0
['Swift']
0
stone-game-v
1563. Stone Game V.cpp
1563-stone-game-vcpp-by-202021ganesh-8x3l
Code\n\nclass Solution {\npublic:\n int stoneGameV(vector<int>& stoneValue) {\n int n = stoneValue.size();\n dp.resize(n, vector<int>(n, -1));\n retu
202021ganesh
NORMAL
2024-10-03T06:24:14.020888+00:00
2024-10-03T06:24:14.020923+00:00
5
false
**Code**\n```\nclass Solution {\npublic:\n int stoneGameV(vector<int>& stoneValue) {\n int n = stoneValue.size();\n dp.resize(n, vector<int>(n, -1));\n return stoneGameV(stoneValue, 0, n - 1);\n }\n private:\n vector<vector<int>> dp;\n int stoneGameV(const vector<int>& stoneValue, int i, int j) {\n if(i>j)\n return 0;\n if(dp[i][j]!=-1)\n return dp[i][j];\n int r=0;\n int l=0;\n for(int s=i;s<=j;s++){\n r+=stoneValue[s];\n }\n int ans=0;\n for (int p = i; p <j; ++p) {\n l+=stoneValue[p];\n r=r-stoneValue[p];\n if (l < r) \n ans = max(ans, l + stoneGameV(stoneValue, i, p));\n else if (l > r) \n ans = max(ans, r + stoneGameV(stoneValue, p+1, j));\n else if(l==r)\n ans = max(ans, l + max(stoneGameV(stoneValue, i, p), stoneGameV(stoneValue, p+1, j)));\n }\n return dp[i][j]=ans;\n }\n};\n```
0
0
['C']
0
stone-game-v
2D DP,WITH PREFIX SUM.
2d-dpwith-prefix-sum-by-damon109-ncwe
Intuition\n Describe your first thoughts on how to solve this problem. \nThe problem is about maximizing Alice\'s score by carefully choosing how to split the a
damon109
NORMAL
2024-09-04T11:29:41.680759+00:00
2024-09-04T11:29:41.680787+00:00
6
false
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\nThe problem is about maximizing Alice\'s score by carefully choosing how to split the array of stones in each round. Alice aims to divide the stones such that Bob is forced to throw away the row with the larger sum, leaving Alice with the row with the smaller sum, which becomes her score for that round. The challenge lies in finding the optimal way to split the array at each step to maximize Alice\'s total score across all rounds.\n# Approach\n<!-- Describe your approach to solving the problem. -->\nPrefix Sum Array:\n\nCreate a prefix sum array to quickly calculate the sum of any subarray. This will help in determining the sums of the left and right partitions during each split.\nDynamic Programming (DP):\n\nDefine a 2D DP table dp[i][j] where dp[i][j] represents the maximum score Alice can obtain from the subarray starting at index i and ending at index j.\nUse a bottom-up approach to fill this DP table. For each possible subarray, iterate through all possible split points to decide the optimal partition that maximizes Alice\'s score.\nBinary Search for Efficient Partitioning:\n\nFor each subarray, instead of checking all possible partitions, use binary search to find the point where the sum of the left partition is as close as possible to the sum of the right partition.\nState Transition:\n\nFor each split point, calculate the potential score for Alice based on whether Bob chooses the left or right partition to discard.\nUpdate dp[i][j] with the maximum score Alice can achieve for that subarray.\nFinal Result:\n\nThe final answer will be stored in dp[0][n-1], which represents the maximum score Alice can achieve starting from the entire array.\nThis approach ensures that Alice\'s score is maximized while also being computationally efficient.\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```cpp []\nclass Solution {\npublic:\n int stoneGameV(vector<int>& sv) {\n int n = sv.size();\n vector<vector<int>> dp(n, vector<int>(n, 0));\n vector<int> prefixSum(n + 1, 0);\n\n // Calculate prefix sum\n for (int i = 0; i < n; ++i) {\n prefixSum[i + 1] = prefixSum[i] + sv[i];\n }\n\n // DP with binary search\n for (int len = 2; len <= n; ++len) {\n for (int i = 0; i + len <= n; ++i) {\n int j = i + len - 1;\n\n for (int k = i; k < j; ++k) {\n int leftSum = prefixSum[k + 1] - prefixSum[i];\n int rightSum = prefixSum[j + 1] - prefixSum[k + 1];\n\n if (leftSum < rightSum) {\n dp[i][j] = max(dp[i][j], dp[i][k] + leftSum);\n } else if (leftSum > rightSum) {\n dp[i][j] = max(dp[i][j], dp[k + 1][j] + rightSum);\n } else {\n dp[i][j] = max(dp[i][j], max(dp[i][k] + leftSum, dp[k + 1][j] + rightSum));\n }\n }\n }\n }\n\n return dp[0][n - 1];\n }\n};\n\n\n\n\n // int n=sv.size(), left=1,right=n,count=0;\n // vector<int> sum;\n // sum.push_back(0);\n // for(int i=0;i<n;i++){\n // sum[i+1]=sv[i]+sum[i];\n // }\n // while(left+1!=right){\n // int ind=*lower_bound(sum.begin(),sum.end(),sum[right]/2);\n // if((sum[right]+1)/2==sum[ind]){\n // //same left and right\n // }else{\n // if((sum[right]+1)/2-sum[ind-1]<sum[ind]-(sum[right]+1)/2){\n // ind=ind-1;\n // }\n \n // }\n // }\n```
0
0
['Dynamic Programming', 'C++']
0
stone-game-v
My Solution
my-solution-by-hope_ma-7uh5
\n/**\n * let `n` be the length of the vector `stoneValue`\n *\n * the dp solution is employed.\n * dp[start][end] stands for the maximum score that Alice can o
hope_ma
NORMAL
2024-09-03T06:33:38.858938+00:00
2024-09-03T16:16:02.803281+00:00
3
false
```\n/**\n * let `n` be the length of the vector `stoneValue`\n *\n * the dp solution is employed.\n * dp[start][end] stands for the maximum score that Alice can obtain from the sub-row whose range is from the index\n * `start` to the index `end` of the vector `stoneValue`, `start` inclusive, `end` exclusive\n *\n * initial:\n * dp[start][start + 1] = 0, where `start` is in the range [0, n - 1], both inclusive\n *\n * induction:\n * let `sum[i][j]` be the sum from stoneValue[i] to stoneValue[j], `i` inclusive, `j` exclusive\n * for every `start`, `end`, where `end` - `start` > 1,\n * let `separator` be an index such that\n * 1) sum[start][separator + 1] >= sum[separator + 1][end] and\n * 2) sum[start][separator] < sum[separator][end],\n * case 1:\n * if sum[start][separator + 1] == sum[separator + 1][end]\n * dp[start][end] = max(\n * sum[start][i] + dp[start][i] for every `i` in the range [start + 1, separator + 1], both inclusive,\n * sum[j][end] + dp[j][end] for every `j` in the range [separator + 1, end - 1], both inclusive\n * )\n * case 2:\n * if sum[start][separator + 1] > sum[separator + 1][end]\n * dp[start][end] = max(\n * sum[start][i] + dp[start][i] for every `i` in the range [start + 1, separator], both inclusive,\n * sum[j][end] + dp[j][end] for every `j` in the range [separator + 1, end - 1], both inclusive\n * )\n * let `left_max[i][j]` stands for\n * max(\n * sum[i][i + 1] + dp[i][i + 1],\n * sum[i][i + 2] + dp[i][i + 2],\n * ...\n * sum[i][j] + dp[i][j]\n * )\n * let `right_max[i][j]` stands for\n * max(\n * sum[j - 1][j] + dp[j - 1][j],\n * sum[j - 2][j] + dp[j - 2][j],\n * ...\n * sum[i][j] + dp[i][j]\n * )\n * `left_max[i][j]` and `right_max[i][j]` can be calculated by the following inductions,\n * left_max[i][j] = max(left_max[i][j - 1], sum[i][j] + dp[i][j])\n * right_max[i][j] = max(right_max[i + 1][j], sum[i][j] + dp[i][j])\n * then `case 1` and `case 2` can be reduced as following,\n * case 1:\n * dp[start][end] = max(left_max[start][separator + 1], right_max[separator + 1][end])\n * case 2:\n * dp[start][end] = max(left_max[start][separator], right_max[separator + 1][end])\n *\n * target:\n * dp[0][n]\n *\n * Time Complexity: O(n * n)\n * Space Complexity: O(n * n)\n */\nclass Solution {\n public:\n int stoneGameV(const vector<int> &stoneValue) {\n const int n = static_cast<int>(stoneValue.size());\n int presums[n + 1];\n memset(presums, 0, sizeof(presums));\n for (int i = 0; i < n; ++i) {\n presums[i + 1] = presums[i] + stoneValue[i];\n }\n\n int separators[n + 1][n + 1];\n memset(separators, 0, sizeof(separators));\n for (int start = 0; start < n; ++start) {\n for (int separator = start, end = start + 1; end < n + 1; ++end) {\n for (; presums[separator + 1] - presums[start] < presums[end] - presums[separator + 1]; ++separator) {\n }\n separators[start][end] = separator;\n }\n }\n \n int dp[n + 1][n + 1];\n memset(dp, 0, sizeof(dp));\n int left_max[n + 1][n + 1];\n memset(left_max, 0, sizeof(left_max));\n int right_max[n + 1][n + 1];\n memset(right_max, 0, sizeof(right_max));\n for (int length = 1; length < n + 1; ++length) {\n for (int start = 0; start + length - 1 < n; ++start) {\n const int end = start + length;\n const int separator = separators[start][end];\n const int left = presums[separator + 1] - presums[start];\n const int right = presums[end] - presums[separator + 1];\n if (left == right) {\n dp[start][end] = max(left_max[start][separator + 1], right_max[separator + 1][end]);\n } else {\n dp[start][end] = max(left_max[start][separator], right_max[separator + 1][end]);\n }\n \n left_max[start][end] = max(left_max[start][end - 1], presums[end] - presums[start] + dp[start][end]);\n right_max[start][end] = max(right_max[start + 1][end], presums[end] - presums[start] + dp[start][end]);\n }\n }\n return dp[0][n];\n }\n};\n```
0
0
[]
0
find-n-unique-integers-sum-up-to-zero
[Java/C++/Python] Find the Rule
javacpython-find-the-rule-by-lee215-1iuj
Intuition\nNaive idea\nn = 1, [0]\nn = 2, [-1, 1]\n\nNow write more based on this\nn = 3, [-2, 0, 2]\nn = 4, [-3, -1, 1, 3]\nn = 5, [-4, -2, 0, 2, 4]\n\nIt spre
lee215
NORMAL
2019-12-30T17:11:21.003630+00:00
2020-01-10T03:05:24.181938+00:00
38,328
false
## **Intuition**\nNaive idea\n`n = 1, [0]`\n`n = 2, [-1, 1]`\n\nNow write more based on this\n`n = 3, [-2, 0, 2]`\n`n = 4, [-3, -1, 1, 3]`\n`n = 5, [-4, -2, 0, 2, 4]`\n\nIt spreads like the wave.\n<br>\n\n## **Explanation**\nFind the rule\n`A[i] = i * 2 - n + 1`\n<br>\n\n## **Math Observation**\n@zzg_zzm helps explain in math.\n\nActually, this rule could be derived from constructing an arithmetic sequence.\n\n(Note that any arithmetic sequence must have unique values if the common delta is non-zero)\n\nWe need the sequence sum, so that\n\n`(a[0] + a[n-1]) * n / 2 = 0`, which means `a[0] + a[n-1] = 0`.\n\nNote that `a[n-1] - a[0] = (n-1) * delta`, which is `-2 * a[0]`,\n\nso we simply set `delta = 2, a[0] = 1 - n`\n<br>\n\n\n## **Note**\nIt\'s not bad to sum up `1 + 2 + 3 + ... + (N - 1)`.\nPersonally I don\'t really like it much.\nWhat is the possible problem of this approach?\nIt doesn\'t work if `N` goes up to `10^5`\n<br>\n\n## **Complexity**\nTime `O(N)`\nSpace `O(N)`\n<br>\n\n**Java:**\n```java\n public int[] sumZero(int n) {\n int[] A = new int[n];\n for (int i = 0; i < n; ++i)\n A[i] = i * 2 - n + 1;\n return A;\n }\n```\n\n**C++:**\n```cpp\n vector<int> sumZero(int n) {\n vector<int> A(n);\n for (int i = 0; i < n; ++i)\n A[i] = i * 2 - n + 1;\n return A;\n }\n```\n\n**Python:**\n```python\n def sumZero(self, n):\n return range(1 - n, n, 2)\n```\n
434
6
[]
61
find-n-unique-integers-sum-up-to-zero
Simple Java : Fill from both sides
simple-java-fill-from-both-sides-by-ansh-xr7n
start filling up from left and right complementary values (so if we insert 1 from left, insert -1 from right, then insert 2 from left and insert -2 from right a
anshu4intvcom
NORMAL
2019-12-29T04:14:58.290894+00:00
2019-12-29T04:14:58.291004+00:00
11,448
false
- start filling up from left and right complementary values (so if we insert 1 from left, insert -1 from right, then insert 2 from left and insert -2 from right and so on) :\n\n```\npublic int[] sumZero(int n) {\n int[] res = new int[n];\n int left = 0, right = n - 1, start = 1;\n while (left < right) {\n res[left++] = start;\n res[right--] = -start;\n start++;\n }\n return res;\n }\n```
153
5
[]
9
find-n-unique-integers-sum-up-to-zero
Keep it simple. Add all values till n-1 and then balance it with -sum.
keep-it-simple-add-all-values-till-n-1-a-02jl
Edited. As @StefanPochmann pointed out rightly. starting from i+1 instead of i to avoid the case of 0 and 0 when n = 2.\n```\nclass Solution {\n public int[]
Nayanava
NORMAL
2019-12-29T04:56:57.541423+00:00
2019-12-29T11:55:01.506084+00:00
7,223
false
Edited. As @StefanPochmann pointed out rightly. starting from i+1 instead of i to avoid the case of 0 and 0 when n = 2.\n```\nclass Solution {\n public int[] sumZero(int n) {\n int arr[] = new int[n];\n int sum = 0;\n for(int i = 0; i < n-1; i++) {\n arr[i] = i+1;\n sum += arr[i];\n }\n arr[n-1] = -sum;\n return arr;\n }\n}
70
6
[]
6
find-n-unique-integers-sum-up-to-zero
Trivial Python/Ruby/Java/C++
trivial-pythonrubyjavac-by-stefanpochman-wmz5
Just use the numbers 1, 2, ..., n-1 as well as their negated sum. I can\'t even be bothered to write the sum formula :-P\n\nPython\n\ndef sumZero(self, n):\n
stefanpochmann
NORMAL
2019-12-29T11:42:16.225447+00:00
2019-12-29T18:15:04.664368+00:00
4,809
false
Just use the numbers 1, 2, ..., n-1 as well as their negated sum. I can\'t even be bothered to write the sum formula :-P\n\n**Python**\n```\ndef sumZero(self, n):\n a = range(1, n)\n return a + [-sum(a)]\n```\n**Ruby**\nSlight variation since `2..n` is one character shorter than `1...n`.\n```\ndef sum_zero(n)\n a = 2..n\n a.to_a << -a.sum\nend\n```\n**Java**\n```\npublic int[] sumZero(int n) {\n int[] a = new int[n];\n for (int i = 1; i < n; i++) {\n a[i] = i;\n a[0] -= i;\n }\n return a;\n}\n```\nShorter but a bit less clear:\n```\npublic int[] sumZero(int n) {\n int[] a = new int[n];\n for (int i = 1; i < n; i++)\n a[0] -= a[i] += i;\n return a;\n}\n```\n**C++**\n```\nvector<int> sumZero(int n) {\n vector<int> a(n);\n for (int i = 1; i < n; i++) {\n a[i] = i;\n a[0] -= i;\n }\n return a;\n}\n```\nShorter but a bit less clear:\n```\nvector<int> sumZero(int n) {\n vector<int> a(n);\n for (int i = 1; i < n; i++)\n a[0] -= a[i] = i;\n return a;\n}\n```
55
6
[]
3
find-n-unique-integers-sum-up-to-zero
Java O(n) solution with explanation 0ms 100%
java-on-solution-with-explanation-0ms-10-sptv
Set the values at each sequential pair of indices such that they sum to 0 and each of these pairs is unique.\nIdea: use i,-i for the values at each pair of indi
eduardrg
NORMAL
2020-11-03T18:17:58.694643+00:00
2020-11-03T18:17:58.694688+00:00
3,421
false
Set the values at each sequential pair of indices such that they sum to 0 and each of these pairs is unique.\nIdea: use ```i,-i``` for the values at each pair of indices ```i, i+1```. \nThis won\'t work if ```i = 0``` because the first two elements would be ```0, 0```. Use ```i+1, -(i+1)``` instead to make it work for all ```i```.\nAfter the loop, all elements up to the last even index are unique and sum to ```0```. We don\'t have to worry if ```n``` is odd because the last element would have been initialized to ```0``` and ```0 + 0 = 0```, so we\'re done.\nStatements in the loop execute ```n/2``` times, so the time complexity is ```O(n)```.\n\n```\nclass Solution {\n public int[] sumZero(int n) {\n int[] result = new int[n];\n for (int i = 0; i < n - 1; i += 2) {\n result[i] = i + 1;\n result[i + 1] = -(i + 1);\n }\n return result;\n }\n}\n```
43
3
['Iterator', 'Java']
4
find-n-unique-integers-sum-up-to-zero
Python3 code: simple and readable with explanation
python3-code-simple-and-readable-with-ex-nvij
Explanation:\n# \nFirst, take a look at a few examples:\n\nn = 1: ans = [0]\nn = 2: ans = [-1,1]\nn = 3: ans = [-1,0,1]\nn = 4: ans = [-2,-1,1,2]\nn = 5: ans =
dr_sean
NORMAL
2020-01-04T22:03:36.359658+00:00
2020-01-05T04:13:06.361346+00:00
7,298
false
# Explanation:\n# \nFirst, take a look at a few examples:\n```\nn = 1: ans = [0]\nn = 2: ans = [-1,1]\nn = 3: ans = [-1,0,1]\nn = 4: ans = [-2,-1,1,2]\nn = 5: ans = [-2,-1,0,1,2]\n```\n\n- So, we should return an array where the values are symmetric. \n- If ```n%2``` is not equal to zero (n is odd), we append 0 to the answer list.\n- The maximum value is equal to ```n//2```; and the minimum value is equal to ```-n//2```.\n- So, we use a ```for``` loop; and each time we add ```-i``` and ```i``` to the answer list. \n\n\n# Python3 code:\n# \n```\n L, rem = n // 2, n % 2\n if rem != 0: ans = [0]\n else: ans = []\n for i in range(1,L+1):\n ans.append(-i)\n ans.append(i) \n return ans\n```
40
2
['Python', 'Python3']
7
find-n-unique-integers-sum-up-to-zero
VERY SIMPLE C++ CODE-
very-simple-c-code-by-nisarg1406-lsol
DO UPVOTE IF YOU FIND IT USEFUL\n\nCODE - \n\nvector<int> sumZero(int n) {\n\t\tvector<int> res;\n if(n == 0) return res;\n if(n%2 != 0) res.push_
nisarg1406
NORMAL
2020-08-29T04:43:02.565726+00:00
2020-08-29T04:43:28.873953+00:00
2,202
false
**DO UPVOTE IF YOU FIND IT USEFUL**\n\nCODE - \n```\nvector<int> sumZero(int n) {\n\t\tvector<int> res;\n if(n == 0) return res;\n if(n%2 != 0) res.push_back(0); //if odd then to push 0\n for(int i=1;i<=floor(n/2);i++){\n res.push_back(i);\n res.push_back(-i);\n }\n return res;\n}\n```
26
1
['C', 'C++']
1
find-n-unique-integers-sum-up-to-zero
Easy to understand javascript beginner friendly
easy-to-understand-javascript-beginner-f-0ons
\n\nvar sumZero = function(n) {\n var num = Math.floor(n/2); \n var res = [];\n\n for(var i=1;i<=num;i++){\n res.push(i,-i)\n } \n\n if(n%2!==0){\n
yutoliho
NORMAL
2020-01-03T00:37:57.480330+00:00
2020-01-03T00:37:57.480364+00:00
2,426
false
\n```\nvar sumZero = function(n) {\n var num = Math.floor(n/2); \n var res = [];\n\n for(var i=1;i<=num;i++){\n res.push(i,-i)\n } \n\n if(n%2!==0){\n res.push(0)\n }\n \n return res \n}\n```
24
1
['JavaScript']
2
find-n-unique-integers-sum-up-to-zero
[Java/Python 3] 2 codes / language.
javapython-3-2-codes-language-by-rock-qso8
Method 1:\njava\n public int[] sumZero(int n) {\n int[] ans = new int[n];\n for (int start = 0, end = n - 1; start < end; ++start, --end) {\n
rock
NORMAL
2019-12-29T04:17:26.564681+00:00
2019-12-29T14:47:23.190887+00:00
1,971
false
**Method 1:**\n```java\n public int[] sumZero(int n) {\n int[] ans = new int[n];\n for (int start = 0, end = n - 1; start < end; ++start, --end) {\n ans[start] = -end;\n ans[end] = end;\n }\n return ans;\n }\n```\n```python\n def sumZero(self, n: int) -> List[int]:\n ans = [0] * n\n start, end = 0, n - 1 \n while start < end:\n ans[start], ans[end] = -end, end\n start, end = start + 1, end - 1 \n return ans\n```\n----\n\n**Method 2: 5 and 1 liners - check odd/even.**\n```java\n public int[] sumZero(int n) {\n int[] ans = new int[n];\n for (int i = -n / 2, k = 0; i <= n / 2; ++i)\n if (i != 0 || n % 2 != 0)\n ans[k++] = i;\n return ans;\n }\n```\n```python\n def sumZero(self, n: int) -> List[int]:\n return [i for i in range((1 - n) // 2, n // 2 + 1) if i != 0 or n % 2 != 0]\n```
18
3
[]
2
find-n-unique-integers-sum-up-to-zero
Brain dead approach. Extendable to non zero sum. Beats 100% || Java
brain-dead-approach-extendable-to-non-ze-s0c7
Intuition\n Describe your first thoughts on how to solve this problem. \n\nYou want ANY array? You will literally get just ANY array!\n\n# Approach\n Describe
pradyot21
NORMAL
2024-06-16T16:36:26.223938+00:00
2024-06-16T16:36:26.223971+00:00
1,050
false
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\nYou want $$ANY$$ array? You will literally get just $$ ANY$$ array!\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\nThe idea probably can\'t get simpler than this.\nWe know the resultant array will be of size *n*. Create an `int` array of size n.\n\n-> Loop until the last element and fill the array with natural numbers. 1, 2, 3, 4, 5 ..... n - 1\n\nWe know that the sum has to be zero. For that to be true, the last element must cancel out the sum of all precending numbers, so we keep a running total while we were iterating above.\n\nHence, last element will be negative of this running total. That\'s it!\n \n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\nO(n) since we need to iterate once for n-1 elements.\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\nLikely a constant since we aren\'t using any other space but an integer sum. Can assume to be O(1)\n\n# Code\n```\nclass Solution {\n public int[] sumZero(int n) {\n int[] result = new int[n];\n int sum = 0;\n\n for (int i = 0; i < n-1; i++) {\n result[i] = i+1;\n sum += result[i];\n }\n result[n - 1] = -1 * sum;\n return result;\n }\n\n}\n```\n\nYou can extend this to a non zero sum by just adjusting the last element by the required value of the sum. Say you are asked for n elements whose sum is 21, then the last element can be `(-1*sum) + 21`\n\n\nPlease let me know if there are any questions.
15
0
['Array', 'Math', 'Java']
6
find-n-unique-integers-sum-up-to-zero
[Java] 0 ms, faster than 100.00% of Java online submissions
java-0-ms-faster-than-10000-of-java-onli-9pnz
```\nclass Solution {\n public int[] sumZero(int n) {\n \n \n int[] ans = new int[n];\n for(int i=0; i<n; i++) {\n ans
anuragbhu
NORMAL
2020-03-19T14:57:54.453615+00:00
2020-03-19T15:03:59.914115+00:00
1,813
false
```\nclass Solution {\n public int[] sumZero(int n) {\n \n \n int[] ans = new int[n];\n for(int i=0; i<n; i++) {\n ans[i] = (i*2)-n+1;\n }\n return ans;\n }\n}
15
0
['Java']
5
find-n-unique-integers-sum-up-to-zero
Two Solutions in Python 3 (one line) (beats 100%) (24 ms)
two-solutions-in-python-3-one-line-beats-vz05
Asymmetric List: (e.g. [1,2,3,4,5,-15])\n\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n return list(range(1,n))+[-n*(n-1)//2]\n\t\t\n\n
junaidmansuri
NORMAL
2019-12-29T04:03:49.596115+00:00
2019-12-29T04:17:16.140242+00:00
2,101
false
_Asymmetric List:_ (e.g. [1,2,3,4,5,-15])\n```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n return list(range(1,n))+[-n*(n-1)//2]\n\t\t\n\n```\n_Symmetric List:_ (e.g. [-2,-1,0,1,2] or [-3,-2,-1,1,2,3])\n```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n return list(range(-(n//2), 0)) + [0]*(n % 2) + list(range(1, n//2 + 1))\n\n \n- Junaid Mansuri\n- Chicago, IL
14
0
['Python', 'Python3']
2
find-n-unique-integers-sum-up-to-zero
C++ || Easy || Explained || ✅
c-easy-explained-by-tridibdalui04-znnb
1. run a loop from 1 to n/2\n### 2. add -i and i in ans vector so that sum can be 0 at end\n#### 3. if size is given odd add 0 to the vector\n\n\n\nclass Solut
tridibdalui04
NORMAL
2022-10-19T12:30:23.717481+00:00
2022-10-19T12:30:23.717522+00:00
889
false
### 1. run a loop from 1 to n/2\n### 2. add -i and i in ans vector so that sum can be 0 at end\n#### 3. if size is given odd add 0 to the vector\n\n\n```\nclass Solution {\npublic:\n vector<int> sumZero(int n) {\n vector<int>ans;\n for(int i=1;i<=n/2;i++)\n {\n ans.push_back(-i);\n ans.push_back(i);\n }\n if(n%2==1)\n ans.push_back(0);\n return ans;\n }\n};\n```
12
0
['Array', 'C']
0
find-n-unique-integers-sum-up-to-zero
Java || easy to understand || faster than 100% || simple answer.
java-easy-to-understand-faster-than-100-pfk2i
\nclass Solution {\n public int[] sumZero(int n) {\n \n int[] ans = new int[n];\n int start = 0;\n int end = n - 1;\n \n
iamridoydey
NORMAL
2022-10-09T11:43:12.585540+00:00
2022-10-09T11:43:12.585584+00:00
1,623
false
```\nclass Solution {\n public int[] sumZero(int n) {\n \n int[] ans = new int[n];\n int start = 0;\n int end = n - 1;\n \n while(start < end){\n ans[start] = start + 1;\n ans[end] = ans[start] * (-1);\n start++;\n end--;\n }\n \n return ans;\n \n }\n}\n```
12
0
['Array', 'Java']
0
find-n-unique-integers-sum-up-to-zero
Swift: Find N Unique Integers Sum up to Zero
swift-find-n-unique-integers-sum-up-to-z-nfu6
swift\nclass Solution {\n func sumZero(_ n: Int) -> [Int] {\n if n <= 1 && 1000 >= n { return [0] }\n var sum = [Int](repeating: 0, count: n)\n
AsahiOcean
NORMAL
2021-04-08T20:49:49.148081+00:00
2021-04-08T21:54:22.291456+00:00
477
false
```swift\nclass Solution {\n func sumZero(_ n: Int) -> [Int] {\n if n <= 1 && 1000 >= n { return [0] }\n var sum = [Int](repeating: 0, count: n)\n for i in 1...(n >> 1) {\n sum[i-1] = i\n sum[n-i] = -i\n }\n return sum\n }\n}\n```
12
1
['Swift']
1
find-n-unique-integers-sum-up-to-zero
Fast python
fast-python-by-travelxcodes-jqse
\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n a=[]\n if n%2!=0:\n a.append(0)\n for i in range(1,n,2):\n
travelXcodes
NORMAL
2022-11-01T04:01:25.909746+00:00
2022-11-01T04:01:25.909784+00:00
960
false
```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n a=[]\n if n%2!=0:\n a.append(0)\n for i in range(1,n,2):\n a.append(i)\n a.append(i*(-1))\n return a\n```
11
0
[]
0
find-n-unique-integers-sum-up-to-zero
Java: fast, clean and short - symmetric array handles both parities
java-fast-clean-and-short-symmetric-arra-31km
Intuition: We can solve this by using pairs of opposites counting away from zero starting with 1, -1 then 2, -2, etc. If we have an odd sized array, we can add
mattihito
NORMAL
2022-05-13T07:04:17.489864+00:00
2022-10-27T02:55:15.851467+00:00
424
false
**Intuition**: We can solve this by using pairs of opposites counting away from zero starting with 1, -1 then 2, -2, etc. If we have an odd sized array, we can add a zero. But what if we like the idea of our array being sorted for easier readability? We can count the left side up starting at -n/2 and increasing left to right, and at the same time, count the right side down starting at n/2 and decreasing right to left.\n\n**Trick**: If we compute half n, and we fill the left side of the array up from -n/2 and fill the right side of the array down from n/2, and if n is even, we are done. But if n is odd, the middle element is already zero from array initialization, and we don\'t have to check it or modify it. Either way, we can do n/2 loop elements and fill from the left and right edges and ignore the odd middle element if there is one. It will already be zero which we want. One less branch is always nice (and can make our code significantly faster when avoided in a loop).\n\n```\nclass Solution {\n\n public int[] sumZero(int n) {\n final int[] answer = new int[n];\n final int halfn = n / 2;\n for (int i = 0; i < halfn; i++) {\n answer[i] = i - halfn; // left increasing: count up from -n/2\n answer[n - i - 1] = halfn - i; // right decreasing: count down from n/2\n }\n\t\t// if n is odd, we filled only n-1 values, but the middle value initialized to 0 and we leave it as-is.\n return answer;\n }\n\n}\n```\n\n**Complexity**: O(n) time, O(1) additional space (O(n) total space including the array for the answer).\n\n**Standard Plea**: If you liked this solution or at least weren\'t annoyed by reading it, **I\'d be glad to have your upvote**. If you didn\'t like it, I\'d love some **constructive feedback in a comment** so I can write better solutions.\n\nThanks, and happy coding!
11
0
['Java']
0
find-n-unique-integers-sum-up-to-zero
Python Solution, Super fast and simple
python-solution-super-fast-and-simple-by-zb43
\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n a=[]\n if n%2!=0:\n a.append(0)\n for i in range(1,n):\n
excalibur12
NORMAL
2020-06-02T02:12:41.423263+00:00
2020-06-02T02:12:41.423312+00:00
1,200
false
```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n a=[]\n if n%2!=0:\n a.append(0)\n for i in range(1,n):\n if len(a)==n:\n break\n a.append(i)\n a.append(-i)\n return a\n```
9
1
['Python']
2
find-n-unique-integers-sum-up-to-zero
C++ 100% solution in 3 lines
c-100-solution-in-3-lines-by-xzcvbzfgefd-zy0b
its just a basic arithmetic series. the ans vector is initialized with the negative sum of all integers up to n - 2. The positive sum can be derived from the in
xzcvbzfgefd
NORMAL
2020-05-29T00:30:13.447653+00:00
2020-05-29T00:31:04.290885+00:00
1,203
false
its just a basic arithmetic series. the ans vector is initialized with the negative sum of all integers up to n - 2. The positive sum can be derived from the integers attained in the loop. These two sets cancel out each other resulting in a total sum of 0.\n\nclass Solution {\npublic:\n vector<int> sumZero(int n) { \n vector<int> ans = {-(n - 2) * (n - 1) / 2}; \n for (int i = 0; i < n - 1; i++)\n ans.push_back(i);\n return ans;\n }\n};
9
3
['C']
1
find-n-unique-integers-sum-up-to-zero
JAVA 100% FASTER and EASY Solution with EXPLANATION
java-100-faster-and-easy-solution-with-e-tdni
JAVA SOLUTION @DeepakKumar\n# In Case of Any Doubt Feel Free to ASK ...\n\n\nclass Solution {\n public int[] sumZero(int n) {\n// Declaring Size of Array of
Deepak2002
NORMAL
2021-11-02T15:03:30.477393+00:00
2021-11-02T15:03:30.477460+00:00
708
false
# JAVA SOLUTION @DeepakKumar\n# In Case of Any Doubt Feel Free to ASK ...\n\n```\nclass Solution {\n public int[] sumZero(int n) {\n// Declaring Size of Array of SIZE n\n int [] resultantArray = new int[n];\n int num = 1; // Start Numbers to Fill from 1\n int start = 0; // Take Start index at 0\n int end = resultantArray.length-1; // Take last Index as n-1\n while(start<end){ // Fill the Array till Start < end\n /*\n Here Note n --> Can be Even or ODD\n n -> EVEN \n Example n = 2\n Index --> 0 1\n [ 0, 0 ]\n Here / \\ \n Start End --> AT the end these will filled by [+x, -x] i.e Symmetric Numbers\n n -> ODD \n Example n = 3\n Index --> 0 1 2\n [ 0, 0, 0 ]\n Here / \\ \n Start End --> AT the end these will filled by [+x, -x] i.e Symmetric Numbers\n --> Here Note that Loop will go till Start < end\n --> But the Mid is Already 0 \n --> Symmetric numbers will cancel Each other in Sum and gives 0 \n --> Hence, 0+0 = 0 \n */\n resultantArray[start] = num; // Fill Start with positive Number +x\n resultantArray[end] = (-num); // Fill End with negative Number -x\n num++; // Increment the Number Because for Next Numbers Because Numbers must be UNIQUE in ARRAY\n start++; // Increment Start\n end--; // Decrement END\n }\n // At the END return the Resultant Array \n return resultantArray;\n \n }\n}\n```
8
0
['Java']
0
find-n-unique-integers-sum-up-to-zero
C++ 0 ms Faster than 100% of submissions
c-0-ms-faster-than-100-of-submissions-by-f90s
\nclass Solution {\npublic:\n vector<int> sumZero(int n) {\n int sum = 0;\n int cnt = 1;\n vector<int> v(n,0);\n for (int i = 0;
tempatron
NORMAL
2020-09-13T11:29:52.356052+00:00
2020-09-13T11:30:04.888314+00:00
1,045
false
```\nclass Solution {\npublic:\n vector<int> sumZero(int n) {\n int sum = 0;\n int cnt = 1;\n vector<int> v(n,0);\n for (int i = 0; i < n ; ++i) {\n if (i != n-1) {\n v[i] = cnt;\n sum += v[i];\n cnt++;\n } else {\n v[i] = -sum;\n }\n }\n return v;\n }\n};\n```
8
0
['C']
1
find-n-unique-integers-sum-up-to-zero
[Python] Simple Solution. Key is to not overthink. (32ms, 14MB)
python-simple-solution-key-is-to-not-ove-rrxs
The key is to not overthink things. As the problem said, you can return any list.\n\nWe only want to iterate until n // 2 because we want half to be positive an
seankala
NORMAL
2020-08-26T09:17:04.770651+00:00
2020-08-26T09:17:04.770693+00:00
575
false
The key is to not overthink things. As the problem said, you can return __*any*__ list.\n\nWe only want to iterate until `n // 2` because we want half to be positive and the other half to be negative integers (excluding 0). For every positive integer, just add its negative counterpart.\n\nIf `n` is an odd number, just add an extra 0 to the end. Problem solved.\n\n````Python\ndef sumZero(n):\n result = []\n \n for i in range(n // 2):\n result.append(i + 1)\n result.append((-1) * (i + 1))\n \n if n % 2 == 1:\n result.append(0)\n \n return result\n````
8
0
['Python', 'Python3']
0
find-n-unique-integers-sum-up-to-zero
Two JS Solutions
two-js-solutions-by-hbjorbj-j4zf
\n/*\nWe can simply add 1 to n-1 and keep track of this array sum and add the negation of that.\n*/\nvar sumZero = function(n) {\n let sum = 0, res = [];\n
hbjorbj
NORMAL
2020-03-30T21:48:17.897318+00:00
2021-05-19T12:15:37.857069+00:00
872
false
```\n/*\nWe can simply add 1 to n-1 and keep track of this array sum and add the negation of that.\n*/\nvar sumZero = function(n) {\n let sum = 0, res = [];\n for (let i = 1; i < n; i++) {\n res.push(i);\n sum += i;\n }\n res.push(-sum);\n return res;\n // T.C: O(N)\n // S.C: O(N)\n};\n```\n\n```\n/*\nWe add pairs of numbers (num, -num) starting from 1 and ending at floor(n/2).\nIf n is odd, we add 0.\n*/\nvar sumZero = function(n) {\n let res = n % 2 === 0 ? [] : [0];\n for (let i = 1; i <= Math.floor(n/2); i++) {\n res.push(i, -i);\n }\n return res;\n // T.C: O(N)\n // S.C: O(N)\n}\n```
8
0
['JavaScript']
3
find-n-unique-integers-sum-up-to-zero
Easy Peasy Python Solution ^_^
easy-peasy-python-solution-_-by-oshine_c-rrvy
Intuition\nHere we get two cases:\nCase 1: \nIf number of elements is odd.\nWe will add a zero at the beginning and rest of the elements will be negative and po
oshine_chan
NORMAL
2023-07-31T08:27:44.795716+00:00
2023-08-02T18:35:01.353308+00:00
471
false
# Intuition\nHere we get two cases:\nCase 1: \nIf number of elements is odd.\nWe will add a zero at the beginning and rest of the elements will be negative and postive integers of ceiling(n/2).\n\nCase 2:\nIf number of elements is even.\nWe will directly add the elements that will be negative and postive integers of ceiling(n/2).\n\n\n# Code\n```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n ans=[]\n nums= int(n/2)\n if n%2!=0:\n ans.append(0)\n for i in range(1,nums+1):\n ans.append(i)\n ans.append(-i)\n return ans\n```\n![neko ask upvote.jpeg](https://assets.leetcode.com/users/images/2a24b906-5cc8-436e-8b46-cb4ab8be1c60_1691001288.110069.jpeg)\n\n
7
0
['Python3']
3
find-n-unique-integers-sum-up-to-zero
JAVA 100% faster solution
java-100-faster-solution-by-bathija111-pyp2
Intuition\n Describe your first thoughts on how to solve this problem. \nThe most important thing to remember here is that when we initialize array in JAVA all
bathija111
NORMAL
2023-01-23T07:09:42.148009+00:00
2023-01-23T07:09:42.148041+00:00
1,186
false
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\nThe most important thing to remember here is that when we initialize array in JAVA all the elements are set to zero initially.\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\nIn this approach we are setting two elements in a single iteration. First we set i-1 to positive i value and i to negative i value which cancels each other and increment i by 2. Now even when n is odd we only set even number of elements and the remaining one element in the end is already "Zero" so it does not affect the solution.\n\n# Complexity\n- Time complexity: O(n)\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution {\n public int[] sumZero(int n) {\n int[] answer = new int[n];\n for (int i = 1; i<n; i+=2) {\n answer[i-1]=i;\n answer[i]=-i;\n }\n return answer;\n }\n}\n```
7
0
['Java']
1
find-n-unique-integers-sum-up-to-zero
JAVA || 100% FASTER || USING IF / ELSE CONDITION.
java-100-faster-using-if-else-condition-96ii7
Upvote this solution, if you like it, that will make me happy.\nHappy Learning\n\n\n# Code\n\nclass Solution {\n public int[] sumZero(int n) {\n int[]
sharforaz_rahman
NORMAL
2022-11-30T05:48:26.501614+00:00
2022-11-30T05:48:26.501659+00:00
1,226
false
Upvote this solution, if you like it, that will make me happy.\nHappy Learning\n\n\n# Code\n```\nclass Solution {\n public int[] sumZero(int n) {\n int[] new_array = new int[n];\n\n int length_for_even = n / 2;\n int length_for_odd = n / 2;\n if (n % 2 != 0) {\n\n for (int i = 1, j = 0; i <= length_for_odd; i++, j++) {\n new_array[j] = i * (-1);\n }\n for (int i = 1, j = length_for_odd + 1; i <= length_for_even; i++, j++) {\n new_array[j] = i;\n }\n } else {\n\n for (int i = 1, j = 0; i <= length_for_odd; i++, j++) {\n new_array[j] = i * (-1);\n }\n for (int i = 1, j = length_for_odd; i <= length_for_even; i++, j++) {\n new_array[j] = i;\n }\n }\n return new_array;\n }\n}\n```
7
0
['Java']
0
find-n-unique-integers-sum-up-to-zero
Easy Python Solution (using range function) - faster + less memory than 95%
easy-python-solution-using-range-functio-o1k1
\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n first_part = list(range(1, n))\n second_part = -sum(first_part)\n return f
ibizak
NORMAL
2021-06-10T13:22:08.456371+00:00
2021-06-10T13:22:08.456417+00:00
353
false
```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n first_part = list(range(1, n))\n second_part = -sum(first_part)\n return first_part + [second_part]\n \n```
7
0
['Array', 'Python']
1
find-n-unique-integers-sum-up-to-zero
✅REALLY easy solution✅
really-easy-solution-by-parijdev-924s
\n# Code\n\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n mass = []\n if n % 2 != 0:\n mass.append(0)\n for i i
parijdev
NORMAL
2024-03-24T18:16:12.238012+00:00
2024-03-24T18:16:12.238043+00:00
378
false
\n# Code\n```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n mass = []\n if n % 2 != 0:\n mass.append(0)\n for i in range(n):\n if len(mass) != n:\n mass.append(-i-1)\n mass.append(i+1)\n return mass\n```\n\n![photo_2024-03-18_21-02-33.jpg](https://assets.leetcode.com/users/images/475f442e-5f7d-4311-b09d-24b8063e2767_1711304070.0371118.jpeg)\n
6
0
['Python3']
2
find-n-unique-integers-sum-up-to-zero
C++ and C# very easy solution.100% faster.
c-and-c-very-easy-solution100-faster-by-d9ztw
\n\nC++ []\nclass Solution {\npublic:\n vector<int> sumZero(int n) {\n vector<int> answer(n);\n int x;\n if(n%2==0){\n x=n/2;\n
aloneguy
NORMAL
2023-04-16T18:21:27.983608+00:00
2023-04-16T18:21:27.983679+00:00
1,319
false
![photo_2023-04-16_23-18-03.jpg](https://assets.leetcode.com/users/images/46606376-8c59-40ca-802d-55006f648a9b_1681669225.7801287.jpeg)\n\n```C++ []\nclass Solution {\npublic:\n vector<int> sumZero(int n) {\n vector<int> answer(n);\n int x;\n if(n%2==0){\n x=n/2;\n answer[n-1]=0;\n }\n else\n x=(n-1)/2; \n for(int i=1;i<=x;i++){ \n answer[i-1]=-1*i; \n answer[i-1+x]=i;\n }\n return answer; \n }\n};\n```\n```C# []\npublic class Solution {\n public int[] SumZero(int n) {\n int[] answer=new int[n];\n int x;\n if(n%2==0){\n x=n/2;\n answer[n-1]=0;\n }\n else\n x=(n-1)/2; \n for(int i=1;i<=x;i++){ \n answer[i-1]=-1*i; \n answer[i-1+x]=i;\n }\n return answer;\n }\n}\n```\n![Vote.png](https://assets.leetcode.com/users/images/cd828259-56f3-4bdb-9b13-464501a593e5_1681669237.8321748.png)\n\n\n\n
6
0
['Math', 'C++', 'C#']
0
find-n-unique-integers-sum-up-to-zero
[Swift] Faster than 100%
swift-faster-than-100-by-blackbirdng-86q2
<- Please vote if my solution was helpful to you.\n\nclass Solution {\n func sumZero(_ n: Int) -> [Int] {\n var result = [Int]()\n var sum = 0\
blackbirdNG
NORMAL
2021-08-01T17:09:37.182322+00:00
2021-08-01T17:11:45.098941+00:00
159
false
<- Please vote if my solution was helpful to you.\n```\nclass Solution {\n func sumZero(_ n: Int) -> [Int] {\n var result = [Int]()\n var sum = 0\n for i in 1..<n {\n result.append(i)\n sum += i\n }\n result.append(-sum)\n return result\n }\n}\n```\n![image](https://assets.leetcode.com/users/images/d8815c44-0339-4a00-a2b5-461b20808930_1627837873.8061256.png)
6
0
['Swift']
1
find-n-unique-integers-sum-up-to-zero
1304 | JavaScript 1-Line Solution
1304-javascript-1-line-solution-by-spork-suu9
Now updated to work with the newly discovered integer "2".\n\n> Runtime: 74 ms, faster than 69.44% of JavaScript online submissions\n> Memory Usage: 44.3 MB, le
sporkyy
NORMAL
2020-03-02T18:07:07.308647+00:00
2022-04-26T20:53:57.602439+00:00
629
false
Now updated to work with the newly discovered integer "2".\n\n> Runtime: **74 ms**, faster than *69.44%* of JavaScript online submissions\n> Memory Usage: **44.3 MB**, less than *5.61%* of JavaScript online submissions\n\n```javascript\n/**\n * @param {number} n\n * @return {number[]}\n */\nconst sumZero = n => [...new Array(n).keys(), ((1 - n) * n) / 2].slice(1);\n```
6
0
['JavaScript']
4
find-n-unique-integers-sum-up-to-zero
[Python 3]. Simple. O(n). 28ms
python-3-simple-on-28ms-by-rohin7-x9l0
Explanation:\n* Return an arithmetic progression with common difference 2, centered around 0\n\n\nclass Solution:\n def sumZero(self, n):\n result=[]\
rohin7
NORMAL
2019-12-29T05:41:34.790260+00:00
2019-12-29T05:54:44.723492+00:00
1,071
false
Explanation:\n* Return an arithmetic progression with common difference 2, centered around 0\n\n```\nclass Solution:\n def sumZero(self, n):\n result=[]\n _int_=-n+1\n for i in range(n):\n result.append(_int_)\n _int_=_int_+2\n return result\n```
6
2
['Python', 'Python3']
3
find-n-unique-integers-sum-up-to-zero
C++||Easy to Understand
ceasy-to-understand-by-return_7-9lpq
```\nclass Solution {\npublic:\n vector sumZero(int n) \n {\n vector ans(n);\n for(int i=0;i<n;i++)\n {\n ans[i]=i*2-n+1;\
return_7
NORMAL
2022-09-13T19:46:16.017323+00:00
2022-09-13T19:46:16.017366+00:00
237
false
```\nclass Solution {\npublic:\n vector<int> sumZero(int n) \n {\n vector<int> ans(n);\n for(int i=0;i<n;i++)\n {\n ans[i]=i*2-n+1;\n }\n return ans;\n \n }\n};\n//if you like the solution plz upvote.
5
0
['C']
0
find-n-unique-integers-sum-up-to-zero
Java Simple Easy Math
java-simple-easy-math-by-himanshu_pandey-o2t5
```class Solution {\n public int[] sumZero(int n) {\n int[] result =new int[n];\n int i=0;\n for ( i=0; i< n-1;i++){\n result[
Himanshu_Pandey1995
NORMAL
2022-04-21T05:44:49.738666+00:00
2022-04-21T05:44:49.738712+00:00
230
false
```class Solution {\n public int[] sumZero(int n) {\n int[] result =new int[n];\n int i=0;\n for ( i=0; i< n-1;i++){\n result[i]=i-n;\n result[i+1]=n-i;\n i++;\n }\n return result;\n }\n}
5
0
['Java']
0
find-n-unique-integers-sum-up-to-zero
Find N Unique Integers Sum up to Zero | Simple Java Solution | Beats 100%
find-n-unique-integers-sum-up-to-zero-si-lsf1
We have to fill the array with equal number of Postive and Negative numbers. Example: if the value of n is 4, then we can have a array [-1, 1, -2, 2]. If "n" is
deleted_user
NORMAL
2021-08-29T14:04:55.145546+00:00
2021-09-02T13:23:51.747112+00:00
297
false
We have to fill the array with equal number of Postive and Negative numbers. Example: if the value of n is 4, then we can have a array [-1, 1, -2, 2]. If "n" is odd, we will add \'0\' to the array. Example: n = 5, then we can have na array with the following values [-1, 1, -2, 2, 0]\n\n```\nclass Solution {\n public int[] sumZero(int n) {\n int [] result = new int [n];\n \n\t\t// We will add one Positive and one negative number.\n\t\t// We have the condition "n-1", so if the value of \'n\' is odd, we wont fill the last cell of the result array. It will be 0 by default.\n for (int index = 0; index < n - 1; index += 2) {\n result [index] = index + 1;\n result [index + 1] = - (index + 1);\n }\n \n return result;\n }\n}\n```
5
0
['Java']
0
find-n-unique-integers-sum-up-to-zero
Java solution, faster than 100%
java-solution-faster-than-100-by-optimal-8csj
class Solution {\n public int[] sumZero(int n) {\n \n\t\tint[] res = new int[n];\n \n int cur = 0;\n if(n%2!=0) {\n res
optimalsis
NORMAL
2020-04-10T02:29:56.615417+00:00
2020-04-10T02:29:56.615473+00:00
321
false
class Solution {\n public int[] sumZero(int n) {\n \n\t\tint[] res = new int[n];\n \n int cur = 0;\n if(n%2!=0) {\n res[cur] = 0;\n cur++;\n }\n \n for(int i=1; i<=n/2; i++) {\n res[cur++] = i;\n res[cur++] = -i;\n }\n \n return res;\n }\n}
5
1
[]
2
find-n-unique-integers-sum-up-to-zero
Simple Java Solution
simple-java-solution-by-mugdhagovilkar11-bs01
\nclass Solution {\n public int[] sumZero(int n) {\n int[] ans = new int[n];\n int num = n/2;\n int index = 0;\n while(num>0)\n
mugdhagovilkar1197
NORMAL
2020-01-09T03:26:03.384783+00:00
2020-01-09T03:26:03.384851+00:00
456
false
```\nclass Solution {\n public int[] sumZero(int n) {\n int[] ans = new int[n];\n int num = n/2;\n int index = 0;\n while(num>0)\n {\n ans[index++] = num;\n ans[index++] = num*-1;\n num--;\n }\n if(n%2 == 1)\n ans[index++] = 0;\n return ans;\n \n }\n}\n```
5
0
['Java']
1
find-n-unique-integers-sum-up-to-zero
JavaScript Solution
javascript-solution-by-ehdwn1212-gbsq
js\nvar sumZero = function(n) {\n const uniqueIntegers = [];\n const half = parseInt(n / 2);\n \n for (let i = 1; i <= half; i++) {\n uniqueI
ehdwn1212
NORMAL
2020-01-06T16:43:31.275727+00:00
2020-01-06T16:43:31.275775+00:00
703
false
```js\nvar sumZero = function(n) {\n const uniqueIntegers = [];\n const half = parseInt(n / 2);\n \n for (let i = 1; i <= half; i++) {\n uniqueIntegers.push(i);\n uniqueIntegers.push(-i);\n }\n \n if (n % 2) {\n uniqueIntegers.push(0);\n }\n \n return uniqueIntegers;\n};\n```
5
0
['JavaScript']
0
find-n-unique-integers-sum-up-to-zero
One Line Rust Solution
one-line-rust-solution-by-wfxr-sx3k
rust\npub fn sum_zero(n: i32) -> Vec<i32> {\n\t(1 - n..n).step_by(2).collect()\n}\n
wfxr
NORMAL
2019-12-31T02:07:31.568002+00:00
2019-12-31T02:07:31.568058+00:00
90
false
```rust\npub fn sum_zero(n: i32) -> Vec<i32> {\n\t(1 - n..n).step_by(2).collect()\n}\n```
5
0
[]
1
find-n-unique-integers-sum-up-to-zero
C# Solution
c-solution-by-leonhard_euler-tf05
\npublic class Solution \n{\n public int[] SumZero(int n) \n {\n var result = new List<int>();\n for(int i = 1; i <= n/2; i++)\n {\n
Leonhard_Euler
NORMAL
2019-12-29T04:57:51.542216+00:00
2019-12-29T04:58:03.905175+00:00
736
false
```\npublic class Solution \n{\n public int[] SumZero(int n) \n {\n var result = new List<int>();\n for(int i = 1; i <= n/2; i++)\n {\n result.Add(i);\n result.Add(-i);\n }\n \n if(n % 2 == 1) result.Add(0);\n return result.ToArray();\n }\n}\n```
5
0
[]
3
find-n-unique-integers-sum-up-to-zero
The most simplest way
the-most-simplest-way-by-nurzhansultanov-3lye
\n\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n result = []\n if n%2==0:\n for i in range(1,(n//2)+1):\n
NurzhanSultanov
NORMAL
2024-02-06T17:11:00.140312+00:00
2024-02-06T17:11:00.140334+00:00
412
false
\n```\nclass Solution:\n def sumZero(self, n: int) -> List[int]:\n result = []\n if n%2==0:\n for i in range(1,(n//2)+1):\n result.append(i)\n result.append((-1)*i)\n result.sort()\n return result\n else:\n for i in range(1,((n-1)//2)+1):\n result.append(i)\n result.append((-1)*i)\n result.append(0)\n result.sort()\n return result\n```
4
0
['Python3']
0
find-n-unique-integers-sum-up-to-zero
BEATS 100%
beats-100-by-nitish_reddy27-8mvg
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time
nitish_reddy27
NORMAL
2023-07-29T08:25:04.371192+00:00
2023-07-29T08:31:12.449755+00:00
823
false
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity: $$O(n)$$\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity: $$O(n)$$\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution {\n public int[] sumZero(int n) {\n int[] ans=new int[n];\n if(n==1){\n ans[n-1]=0;\n return ans;\n }\n int temp=0;\n if(n%2==0) temp=n;\n if(n%2!=0){\n temp=n-1;\n ans[n-1]=0;\n }\n for(int i=0;i<temp;i+=2){\n ans[i]=i+1;\n ans[i+1]=-(i+1);\n }\n return ans;\n }\n}\n```
4
0
['Java']
2