solution
stringlengths 11
983k
| difficulty
int64 0
21
| language
stringclasses 2
values |
|---|---|---|
#include <bits/stdc++.h>
using namespace std;
int sc(int &x) { return scanf("%d", &x); }
int sc(unsigned int &x) { return scanf("%u", &x); }
int sc(long long &x) { return scanf("%lld", &x); }
int sc(unsigned long long &x) { return scanf("%llu", &x); }
int sc(double &x) { return scanf("%lf", &x); }
int sc(long double &x) { return scanf("%Lf", &x); }
int sc(char *x) { return scanf("%s", x); }
int sc(char &x) { return scanf("%c", &x); }
template <typename T, typename... Args>
void sc(T &v, Args &...args) {
sc(v);
sc(args...);
}
void pr(const int &x) { printf("%d", x); }
void pr(const unsigned int &x) { printf("%u", x); }
void pr(const long long &x) { printf("%lld", x); }
void pr(const unsigned long long &x) { printf("%llu", x); }
void pr(const double &x) { printf("%.10lf", x); }
void pr(const long double &x) { printf("%.10Lf", x); }
void pr(const char *const &x) { printf("%s", x); }
void pr(char *const &x) { printf("%s", x); }
void pr(const char &x) { printf("%c", x); }
template <typename T, typename... Args>
void pr(T const &v, Args const &...args) {
pr(v);
pr(' ');
pr(args...);
}
const long long MOD = 1e9 + 7;
inline void _add(long long &a, long long b) { a = (a + b) % MOD; }
inline void _sub(long long &a, long long b) { a = (a + MOD - b) % MOD; }
inline void _mul(long long &a, long long b) { a = (long long)a * b % MOD; }
inline long long _Add(long long a, long long b) { return (a + b) % MOD; }
inline long long _Sub(long long a, long long b) { return (a + MOD - b) % MOD; }
inline long long _Mul(long long a, long long b) { return a * b % MOD; }
int deg[100100], n;
int main() {
sc(n);
int u, v;
for (int i = 1, lim = n - 1; i <= lim; ++i) {
sc(u, v);
deg[u]++;
deg[v]++;
}
for (int i = 1, lim = n; i <= lim; ++i) {
if (deg[i] == 2) {
pr("NO");
return 0;
}
}
pr("YES");
pr("\n");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const long long N = 100005;
long long degree[N];
int main() {
long long n, i, v, u;
cin >> n;
for (i = 0; i < n - 1; i++) {
cin >> v >> u;
degree[v]++;
degree[u]++;
}
for (i = 1; i <= n; i++) {
if (degree[i] == 2) {
cout << "NO\n";
;
return 0;
}
}
cout << "YES\n";
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
const int inff = 0x3f3f3f3f;
const double eqs = 1e-9;
const double E = 2.718281828459;
const double pi = acos(-1.0);
using namespace std;
const int maxn = 1e5 + 5;
int in[maxn];
int main() {
int n, x, y;
cin >> n;
for (int i = 1; i <= n; i++) in[i] = 0;
for (int i = 1; i < n; i++) {
scanf("%d %d", &x, &y);
in[x]++, in[y]++;
}
for (int i = 1; i <= n; i++)
if (in[i] == 2) {
puts("NO");
return 0;
}
puts("YES");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1e5 + 5;
int n;
vector<int> G[MAX_N];
bool ans = true;
int main() {
scanf("%d", &n);
for (int i = 0, t1, t2; i < n - 1; i++) {
scanf("%d%d", &t1, &t2);
G[t1].emplace_back(t2);
G[t2].emplace_back(t1);
}
for (int i = 1; i <= n; i++)
if (G[i].size() == 2) {
ans = false;
break;
}
puts(ans ? "YES" : "NO");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int n;
vector<vector<int> > a;
void Input() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n;
a.resize(n);
for (int i = 1; i <= n - 1; i++) {
int x, y;
cin >> x >> y;
x--;
y--;
a[x].push_back(y);
a[y].push_back(x);
}
}
void Process() {
for (int i = 0; i <= n - 1; i++)
if (a[i].size() == 2) {
cout << "NO";
return;
}
cout << "YES";
}
int main() {
Input();
Process();
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
long long br[200002];
long long n, x, y;
int main() {
cin >> n;
for (long long i = 1; i < n; i++) {
cin >> x >> y;
br[x]++;
br[y]++;
}
for (long long i = 1; i <= n; i++) {
if (br[i] == 2) {
cout << "NO\n";
return 0;
}
}
cout << "YES\n";
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const unsigned long long hash1 = 201326611;
const unsigned long long hash2 = 50331653;
const int N = 200000 + 10;
const int M = 20;
vector<int> g[N];
int n, vis[N];
int main() {
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
cin >> n;
int u, v;
for (int i = 1; i < n; i++) {
cin >> u >> v;
vis[u]++;
vis[v]++;
}
int flag = 0;
for (int i = 1; i <= n; i++) {
if (vis[i] == 2) flag = 1;
}
if (flag)
cout << "NO" << endl;
else
cout << "YES" << endl;
return 0;
}
| 10 | CPP |
n = int(input())
l = [0] * n
for i in range(n - 1):
u , v = map(int , input().split())
l[u - 1] += 1
l[v - 1] += 1
for i in l:
if i == 2:
print("NO")
exit()
print("YES")
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
vector<long long> adj[200005];
long long c = 0;
bool vis[200005];
vector<long long> lf;
void dfs(long long v) {
if (vis[v]) {
return;
}
vis[v] = true;
if (adj[v].size() == 1) {
c++;
lf.push_back(v);
}
for (auto u : adj[v]) {
dfs(u);
}
}
int main() {
long long n;
cin >> n;
long long x, y;
for (int i = 0; i < n - 1; i++) {
cin >> x >> y;
adj[x].push_back(y);
adj[y].push_back(x);
}
dfs(x);
for (int i = 1; i <= n; i++) {
if (adj[i].size() == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
return 0;
}
| 10 | CPP |
from sys import stdin, stdout, exit
n = int(input())
graph = [[] for i in range(n)]
for i in range(n-1):
u, v = map(int, stdin.readline().split())
graph[u-1].append(v-1)
graph[v-1].append(u-1)
for i in range(n):
if len(graph[i]) == 2:
print("NO")
exit()
print("YES")
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
int main() {
int n, u, v;
cin >> n;
vector<vector<int>> g(n);
for (int i = 0; i < n - 1; i++) {
cin >> u >> v;
g[u - 1].push_back(v - 1);
g[v - 1].push_back(u - 1);
}
for (int i = 0; i < n; i++) {
if (g[i].size() == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e5 + 1;
int d[MAX];
void solve() {
int n;
cin >> n;
for (int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
d[u]++;
d[v]++;
}
for (int i = 1; i <= n; ++i) {
if (d[i] == 2) {
cout << "NO\n";
return;
}
}
cout << "YES\n";
}
int main() {
ios::sync_with_stdio(false);
cin.tie(NULL);
solve();
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
vector<int> a[100010];
int main() {
int n, m;
scanf("%d", &n);
int x, y;
for (int i = 0; i < n - 1; i++) {
scanf("%d%d", &x, &y);
a[x].push_back(y);
a[y].push_back(x);
}
if (n == 2) {
printf("YES");
return 0;
}
int f = 1;
for (int i = 1; i <= n; i++) {
if (a[i].size() == 2) {
f = 0;
break;
}
}
if (f)
printf("YES");
else
printf("NO");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const int O = 1e6;
const int mod = 1e9 + 7;
const int maxn = 1e6 + 5;
const double PI = acos(-1.0);
const double E = 2.718281828459;
const double eps = 1e-8;
struct dd {
int to, val, next;
} e[maxn];
int head[maxn], cnt = 0;
void add(int u, int v) {
e[cnt] = {v, 0, head[u]};
head[u] = cnt++;
}
int main() {
memset(head, -1, sizeof(head));
int n;
scanf("%d", &n);
int num[maxn];
memset(num, 0, sizeof(num));
for (int i = 0; i < n - 1; i++) {
int u, v;
scanf("%d%d", &u, &v);
num[u]++;
num[v]++;
}
bool flag = true;
for (int i = 1; i <= n; i++) {
if (num[i] == 2) flag = false;
}
flag ? printf("YES\n") : printf("NO\n");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
vector<long long> vin(long long n) {
vector<long long> a(n);
for (long long i = 0; i < n; i += 1) cin >> a[i];
return a;
}
long long intin() {
long long n;
cin >> n;
return n;
}
char charin() {
char a;
cin >> a;
return a;
}
string strin() {
string s;
cin >> s;
return s;
}
long long factorial(long long n) {
return (n == 1 || n == 0) ? 1 : n * factorial(n - 1);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
long long n, u, v;
cin >> n;
vector<long long> counter(n + 1, 0);
for (long long i = 0; i < n - 1; i += 1) {
cin >> u >> v;
counter[u]++;
counter[v]++;
}
for (auto i : counter) {
if (i == 2) {
cout << "NO\n";
return 0;
}
}
cout << "YES\n";
return 0;
}
| 10 | CPP |
from collections import Counter
n = int(input())
x = []
for _ in range(n-1):
x.extend(input().split())
print('NO' if 2 in Counter(x).values() else 'YES')
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
long long n;
cin >> n;
vector<vector<long long>> v(n);
for (long long i = 0; i < n - 1; i++) {
long long a, b;
cin >> a >> b;
v[a - 1].push_back(b - 1);
v[b - 1].push_back(a - 1);
}
for (long long i = 0; i < n; i++) {
if (v[i].size() == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
}
| 10 | CPP |
import sys, os
from io import BytesIO, IOBase
from math import floor, gcd, fabs, factorial, fmod, sqrt, inf, log
from collections import defaultdict as dd, deque
from heapq import merge, heapify, heappop, heappush, nsmallest
from bisect import bisect_left as bl, bisect_right as br, bisect
# region fastio
BUFSIZE = 8192
class FastIO(IOBase):
newlines = 0
def __init__(self, file):
self._fd = file.fileno()
self.buffer = BytesIO()
self.writable = "x" in file.mode or "r" not in file.mode
self.write = self.buffer.write if self.writable else None
def read(self):
while True:
b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
if not b:
break
ptr = self.buffer.tell()
self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
self.newlines = 0
return self.buffer.read()
def readline(self):
while self.newlines == 0:
b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
self.newlines = b.count(b"\n") + (not b)
ptr = self.buffer.tell()
self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
self.newlines -= 1
return self.buffer.readline()
def flush(self):
if self.writable:
os.write(self._fd, self.buffer.getvalue())
self.buffer.truncate(0), self.buffer.seek(0)
class IOWrapper(IOBase):
def __init__(self, file):
self.buffer = FastIO(file)
self.flush = self.buffer.flush
self.writable = self.buffer.writable
self.write = lambda s: self.buffer.write(s.encode("ascii"))
self.read = lambda: self.buffer.read().decode("ascii")
self.readline = lambda: self.buffer.readline().decode("ascii")
stdin, stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
mod = pow(10, 9) + 7
mod2 = 998244353
def inp(): return stdin.readline().strip()
def iinp(): return int(inp())
def out(var, end="\n"): stdout.write(str(var)+"\n")
def outa(*var, end="\n"): stdout.write(' '.join(map(str, var)) + end)
def lmp(): return list(mp())
def mp(): return map(int, inp().split())
def smp(): return map(str, inp().split())
def l1d(n, val=0): return [val for i in range(n)]
def l2d(n, m, val=0): return [l1d(m, val) for j in range(n)]
def remadd(x, y): return 1 if x%y else 0
def ceil(a,b): return (a+b-1)//b
S1 = 'abcdefghijklmnopqrstuvwxyz'
S2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
def isprime(x):
if x<=1: return False
if x in (2, 3): return True
if x%2 == 0: return False
for i in range(3, int(sqrt(x))+1, 2):
if x%i == 0: return False
return True
n = iinp()
edges = l1d(n+1)
for i in range(n-1):
x, y = mp()
edges[x] += 1
edges[y] += 1
flg = True
for i in edges:
if i==2:
flg = False
break
print("YES" if flg else "NO") | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
long long n, m, x, y, d[100005];
vector<long long> a[100005];
void solve() {
cin >> n;
m = n - 1;
while (m--) {
cin >> x >> y;
a[x].push_back(y);
a[y].push_back(x);
d[x]++, d[y]++;
}
for (__typeof((n + 1)) i = (1); i < (n + 1); i++) {
if (d[i] == 2) {
cout << "NO"
<< "\n";
return;
};
}
{
cout << "YES"
<< "\n";
return;
};
}
void prep() {}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
long long t = 1;
prep();
cout << fixed << setprecision(12);
while (t--) solve();
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
long long n, l, r, cnt = 0;
cin >> n;
vector<long long> v[n + 1];
bool ok = true;
for (long long i = 0; i < n - 1; ++i) {
cin >> l >> r;
v[l].push_back(r);
v[r].push_back(l);
}
for (long long i = 1; i <= n; ++i) {
if (v[i].size() == 2) ok = false;
}
cout << ((ok) ? "YES\n" : "NO\n");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
vector<int> AL[100005];
int main() {
int n;
scanf("%d", &n);
for (int i = 0; i < n - 1; i++) {
int u, v;
scanf("%d", &u);
scanf("%d", &v);
AL[u].push_back(v);
AL[v].push_back(u);
}
long long int l = 0;
int fl = 0;
for (int i = 1; i <= n; i++) {
if (AL[i].size() == 2) {
fl = 1;
}
}
if (fl == 0) {
printf("YES\n");
} else {
printf("NO\n");
}
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int g[100010];
int f;
int main() {
int n, i, j, ok = 0, x, y;
scanf("%d", &n);
for (i = 1; i < n; i++) {
scanf("%d%d", &x, &y);
g[x]++;
g[y]++;
}
for (i = 1; i <= n; i++) {
if (g[i] == 1) f++;
if (g[i] == 2) ok = 1;
}
f = (f * (f - 1)) / 2;
if (ok)
printf("NO");
else
printf("YES");
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector<int> adj[n];
int u, v;
for (int i = 0; i < n - 1; i++) {
cin >> u >> v;
u--;
v--;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 0; i < n; i++) {
if (adj[i].size() == 2) {
cout << "NO" << endl;
return 0;
}
}
cout << "YES" << endl;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100005;
int n, root, Over;
vector<int> P[MAXN];
int main() {
scanf("%d", &n);
for (int i = 1, u, v; i < n; i++) {
scanf("%d%d", &u, &v);
P[u].push_back(v);
P[v].push_back(u);
}
for (int i = 1; i <= n; i++)
if (P[i].size() == 2) {
printf("NO\n");
return 0;
}
printf("YES\n");
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
long long in[100005];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
long long n, x, y;
cin >> n;
for (long long i = 0; i < n - 1; i++) {
cin >> x >> y;
in[x]++;
in[y]++;
}
long long cnt = 0;
bool first = 1;
for (long long i = 1; i < n + 1; i++) {
if (in[i] == 1) cnt++;
if (in[i] == 2) {
first = 0;
break;
}
}
if (first == 0) {
cout << "NO"
<< "\n";
return 0;
}
if ((cnt * (cnt - 1)) / 2 >= n - 1) {
cout << "YES"
<< "\n";
} else {
cout << "NO"
<< "\n";
}
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int n, u, v, z = 0, f[100001];
int main() {
for (int i = 1; i <= 10000; i++) z++;
for (int i = 1; i <= 100; i++) z--;
cin >> n;
for (int i = 1; i < n; i++) {
cin >> u >> v;
f[u]++;
f[v]++;
}
for (int i = 1; i <= n; i++)
if (f[i] != 1 && f[i] <= 2) {
cout << "NO";
return 0;
}
cout << "YES";
return 0;
}
| 10 | CPP |
n=int(input())
dic={}
for x in range(n-1):
a,b=list(map(int,input().split()))
if a in dic:
dic[a]+=1
else:
dic[a]=1
if b in dic:
dic[b]+=1
else:
dic[b]=1
flag=5
for it in dic:
if dic[it]==2:
flag=6
break
if flag==6:
print("NO")
else:
print("YES") | 10 | PYTHON3 |
n = int(input())
deg = [0 for i in range(n+1)]
for i in range(n-1):
a,b = [int(j) for j in input().split(" ")]
deg[a] += 1
deg[b] += 1
ans = "YES"
for i in range(n+1):
if deg[i] == 2:
ans = "NO"
break
print(ans) | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
int n, x, y;
vector<int> g[100010];
int main() {
cin >> n;
for (int i = 0; i < n - 1; i++) {
scanf("%d%d", &x, &y);
g[x].push_back(y);
g[y].push_back(x);
}
for (int i = 1; i <= n; i++) {
if (g[i].size() == 2) {
puts("NO");
return 0;
}
}
puts("YES");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
long long int n;
vector<long long int> G[200020];
int main() {
ios::sync_with_stdio(false);
cin >> n;
for (int i = 0; i < n - 1; i++) {
int x, y;
cin >> x >> y;
G[x].push_back(y);
G[y].push_back(x);
}
for (int i = 1; i <= n; i++) {
if (G[i].size() == 2) return cout << "NO", 0;
}
cout << "YES";
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int dirx[] = {1, -1, 0, 0}, diry[] = {0, 0, 1, -1};
long long bigmod(long long x, long long p) {
long long res = 1;
while (p) {
if (p & 1) res = (res * x) % 998244353;
x = (x * x) % 998244353;
p >>= 1;
}
return res;
}
int32_t main() {
ios_base::sync_with_stdio(false);
int n, m;
cin >> n;
m = n - 1;
vector<int> cnt(n);
while (m--) {
int u, v;
cin >> u >> v;
cnt[u - 1]++;
cnt[v - 1]++;
}
int i = 0;
for (; i < n; i++)
if (cnt[i] == 2) break;
cout << (i < n ? "NO" : "YES\n");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int g[100005];
int main() {
int n;
memset(g, 0, sizeof(g));
cin >> n;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
g[u]++;
g[v]++;
}
for (int i = 1; i <= n; i++) {
if (g[i] == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
;
const double eps = 1e-8;
const int mod = 1e9 + 7;
const int maxn = 3e5 + 5;
const int INF = 0x3f3f3f3f;
const long long INFLL = 0x3f3f3f3f3f3f3f3f;
struct EDGE {
int v, nxt;
} edge[maxn << 1];
int head[maxn], tot;
void add_edge(int u, int v) {
edge[tot].v = v, edge[tot].nxt = head[u], head[u] = tot++;
}
int degree[maxn];
int main() {
memset(head, -1, sizeof(head));
tot = 0;
int n;
scanf("%d", &n);
for (int i = 1, u, v; i < n; i++) {
scanf("%d%d", &u, &v);
degree[u]++;
degree[v]++;
}
bool flag = true;
for (int i = 1; i <= n; i++) {
if (degree[i] == 2) {
flag = false;
}
}
if (flag) {
printf("YES\n");
} else {
printf("NO\n");
}
return 0;
}
| 10 | CPP |
n = int(input())
neigh = [[] for _ in range(n)]
for i in range(n-1):
u, v = map(int, input().split())
u -= 1
v -= 1
neigh[u].append(v)
neigh[v].append(u)
no = False
for i in range(n):
if len(neigh[i]) == 2:
no = True
if no:
print('NO')
else:
print('YES')
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 7;
const int BASE = 1e9 + 7;
const int dx[4] = {-1, 1, 0, 0};
const int dy[4] = {0, 0, -1, 1};
const int N = 1e5 + 1;
vector<int> a[N];
int pa[N], n;
int F[N];
void DFS(int p, int u) {
bool Check = true;
for (__typeof(a[u].begin()) it = a[u].begin(); it != a[u].end(); it++) {
int v = *it;
if (v == p) continue;
Check = false;
DFS(u, v);
pa[v] = u;
F[u] = F[u] + F[v];
}
F[u] += Check;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n;
int u, v;
for (int i = 1; i < n; i++) {
cin >> u >> v;
a[u].push_back(v);
a[v].push_back(u);
}
bool Check = true;
for (int u = 1; u <= n; u++) {
for (__typeof(a[u].begin()) it = a[u].begin(); it != a[u].end(); it++) {
int v = *it;
if (a[u].size() == 1) {
if (a[v].size() == 1) continue;
if (a[v].size() < 3) {
Check = false;
}
} else if (a[v].size() == 1) {
if (a[u].size() == 1) continue;
if (a[u].size() < 3) {
Check = false;
}
} else {
if (a[v].size() < 3 || a[u].size() < 3) {
Check = false;
}
}
}
}
cout << (Check ? "YES" : "NO");
}
| 10 | CPP |
import sys
input = lambda: sys.stdin.readline().strip()
n = int(input())
graph = {}
for i in range(1, n+1): graph[i] = []
for i in range(1, n):
a, b = map(int, input().split())
graph[a].append(b)
graph[b].append(a)
for i in range(1, n+1):
if len(graph[i])==2:
print("NO")
break
else: print("YES")
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
long long power(long long x, long long y, long long p) {
long long res = 1;
x = x % p;
while (y > 0) {
if (y & 1) res = (res * x) % p;
y = y >> 1;
x = (x * x) % p;
}
return res;
}
std::vector<long long> edge[100045];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
long long t, i, j, n, m, k, q, temp, x, y;
{
long long count = 0;
bool flag = 0;
long long a[200050] = {0};
string s;
cin >> n;
for (int i = 0; i < n - 1; i++) {
cin >> x >> y;
edge[x].push_back(y);
edge[y].push_back(x);
}
{
flag = true;
for (i = 1; i <= n; i++) {
if (edge[i].size() == 2) {
flag = false;
}
}
if (flag) {
cout << "YES" << endl;
} else {
cout << "NO" << endl;
}
}
}
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
bool is_prime(long long n) {
for (long long i = 2; i * i <= n; ++i) {
if (n % i == 0) {
return false;
}
}
return true;
}
vector<long long> fact(long long n) {
n = abs(n);
vector<long long> ans;
for (int i = 1; i * i <= n; i++) {
if (n % i == 0) {
ans.push_back(i);
ans.push_back(n / i);
}
}
return ans;
}
inline long long getPow(long long a, long long b) {
long long res = 1ll, tp = a;
while (b) {
if (b & 1ll) {
res *= tp;
}
tp *= tp;
b >>= 1ll;
}
return res;
}
long long vec_mult(long long x1, long long y1, long long x2, long long y2,
long long x3, long long y3) {
return abs((x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1));
}
void ok() {
cout << "YES" << endl;
exit(0);
}
void no() {
cout << "NO" << endl;
exit(0);
}
inline long long nxt() {
long long x;
cin >> x;
return x;
}
const long long N = 3e5 + 5, inf = 8e18;
int days[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
long long n = nxt();
vector<vector<long long>> g(n);
for (int i = 1; i < n; i++) {
long long t1 = nxt() - 1, t2 = nxt() - 1;
g[t1].push_back(t2);
g[t2].push_back(t1);
}
map<long long, long long> mp;
for (auto x : g) {
if (x.size() == 2) {
no();
}
}
ok();
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int n, a, b;
vector<int> adj[100005];
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
for (int i = (int)1; i <= (int)n - 1; i++) {
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
for (int i = (int)1; i <= (int)n; i++)
if (adj[i].size() == 2) {
cout << "NO";
return 0;
}
cout << "YES";
}
| 10 | CPP |
n = int(input())
node = []
for i in range(1 + n):
node.append( [] )
for q in range(n - 1):
k = list(map(int, input().split()))
node[ k[0] ].append( k[1] )
node[ k[1] ].append( k[0] )
hobe = True
for i in range(n + 1):
if(len(node[i]) == 2):
hobe = False
if hobe :
print("YES")
else :
print("NO") | 10 | PYTHON3 |
#! /usr/bin/env python3
import sys
from math import factorial
class Node:
def __init__(self, num):
self.num = num
self.binds = []
# for dijkstra
self.marker = False
self.val = None
def add_bind(self, oth):
self.binds.append(oth)
def __repr__(self):
return '<{}: {}{}>'.format(
self.num,
[i.num for i in self.binds],
', \tval: {}'.format(self.val) if self.val != None else ''
)
class Graph:
def __init__(self, size):
self.size = size
self.nodes = [None] + [Node(num) for num in range(1, size+1)]
def read_input(self):
for _ in range(1, self.size):
i, j = (int(x) for x in sys.stdin.readline().split())
self.nodes[i].add_bind(self.nodes[j])
self.nodes[j].add_bind(self.nodes[i])
def __repr__(self):
return '\n'.join(str(node) for node in self.nodes[1:])
def pairs(n):
return factorial(n) // ( factorial(n-2) * 2 )
N = int(sys.stdin.readline())
g = Graph(N)
g.read_input()
#print(g)
ends = [node for node in g.nodes[1:] if len(node.binds) == 1]
#print('YES' if pairs(len(ends)) >= N-1 else 'NO')
for n in g.nodes[1:]:
if len(n.binds) == 2:
print('NO')
break
else:
print('YES') | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
const long long inff = 0x3f3f3f3f3f3f3f3f;
int n, x, y, du[100008];
int main() {
cin.tie(0);
cout.tie(0);
cin >> n;
for (int i(1); i <= (n - 1); ++i) {
scanf("%d", &x), scanf("%d", &y);
du[x]++, du[y]++;
}
for (int i(1); i <= (n); ++i)
if (du[i] == 2) return puts("NO"), 0;
puts("YES");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int main() {
int n, f = 0;
cin >> n;
vector<int> V[100008];
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
V[u].push_back(v);
V[v].push_back(u);
}
for (int i = 0; i <= n; i++) {
if (V[i].size() == 2) {
f = 1;
break;
}
}
if (f)
cout << "NO" << endl;
else
cout << "YES" << endl;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int cnt[100005];
int main() {
int n;
scanf("%d", &n);
if (n == 2) {
printf("YES\n");
return 0;
}
if (n == 3) {
printf("NO\n");
return 0;
}
for (int i = 0; i < n - 1; i++) {
int u, v;
scanf("%d%d", &u, &v);
cnt[u]++;
cnt[v]++;
}
for (int i = 1; i <= n; i++) {
if (cnt[i] == 2) {
printf("NO\n");
return 0;
}
}
printf("YES\n");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int n;
vector<int> v[101010];
int main() {
scanf("%d", &n);
for (int i = 1; i < n; i++) {
int a, b;
scanf("%d %d", &a, &b);
v[a].push_back(b);
v[b].push_back(a);
}
for (int i = 1; i <= n; i++)
if (v[i].size() == 2) return !printf("NO");
printf("YES");
}
| 10 | CPP |
n=int(input())
a=[0]*n
for i in range(n-1):
c,d=map(int,input().split())
a[c-1]+=1
a[d-1]+=1
stat=2 in a
if(stat):
print('NO')
else:
print('YES') | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
vector<int> g[100005];
int find(int v, int* parent) {
if (parent[v] == v) {
return v;
}
return find(parent[v], parent);
}
int vis[100005];
int dp[100005];
int dfs(int u) {
vis[u] = 1;
for (int i = 0; i < g[u].size(); i++) {
int v = g[u][i];
if (!vis[v]) dfs(v);
}
}
int main() {
int n;
cin >> n;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
for (int i = 1; i <= n; i++) {
if (g[i].size() == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
int main() {
long long in[100005];
long long n, i, j, m, t;
memset(in, 0, sizeof(in));
scanf("%lld", &n);
for (i = 1; i <= n - 1; i++) {
long long u, v;
scanf("%lld %lld", &u, &v);
in[u]++;
in[v]++;
}
long long num = 0;
long long ans = 0;
int flag = 1;
for (i = 1; i <= n; i++) {
if (in[i] == 1) num++;
if (in[i] == 2) flag = 0;
}
num--;
ans = (1 + num) * num / 2;
if (ans >= n - 1 && flag)
printf("YES\n");
else
printf("NO\n");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
vector<vector<int>> adj;
int main() {
int n;
cin >> n;
adj = vector<vector<int>>(n + 1);
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
string ans = "YES\n";
int flag = 1;
for (int i = 1; i <= n; i++) {
if (adj[i].size() == 2) {
ans = "NO\n";
flag = 0;
break;
}
}
cout << ans;
return 0;
}
| 10 | CPP |
import sys
input = sys.stdin.readline
from collections import deque
class Graph(object):
"""docstring for Graph"""
def __init__(self,n,d): # Number of nodes and d is True if directed
self.n = n
self.graph = [[] for i in range(n)]
self.parent = [-1 for i in range(n)]
self.directed = d
def addEdge(self,x,y):
self.graph[x].append(y)
if not self.directed:
self.graph[y].append(x)
def bfs(self, root): # NORMAL BFS
queue = [root]
queue = deque(queue)
vis = [0]*self.n
while len(queue)!=0:
element = queue.popleft()
vis[element] = 1
count = 0
for i in self.graph[element]:
if vis[i]==0:
queue.append(i)
self.parent[i] = element
vis[i] = 1
count += 1
if count==1 and element!=root:
return False
return True
def dfs(self, root, ans): # Iterative DFS
stack=[root]
vis=[0]*self.n
stack2=[]
while len(stack)!=0: # INITIAL TRAVERSAL
element = stack.pop()
if vis[element]:
continue
vis[element] = 1
stack2.append(element)
for i in self.graph[element]:
if vis[i]==0:
self.parent[i] = element
stack.append(i)
while len(stack2)!=0: # BACKTRACING. Modify the loop according to the question
element = stack2.pop()
m = 0
for i in self.graph[element]:
if i!=self.parent[element]:
m += ans[i]
ans[element] = m
return ans
def shortestpath(self, source, dest): # Calculate Shortest Path between two nodes
self.bfs(source)
path = [dest]
while self.parent[path[-1]]!=-1:
path.append(parent[path[-1]])
return path[::-1]
def detect_cycle(self):
indeg = [0]*self.n
for i in range(self.n):
for j in self.graph[i]:
indeg[j] += 1
q = deque()
vis = 0
for i in range(self.n):
if indeg[i]==0:
q.append(i)
while len(q)!=0:
e = q.popleft()
vis += 1
for i in self.graph[e]:
indeg[i] -= 1
if indeg[i]==0:
q.append(i)
if vis!=self.n:
return True
return False
def reroot(self, root, ans):
stack = [root]
vis = [0]*n
while len(stack)!=0:
e = stack[-1]
if vis[e]:
stack.pop()
# Reverse_The_Change()
continue
vis[e] = 1
for i in graph[e]:
if not vis[e]:
stack.append(i)
if self.parent[e]==-1:
continue
# Change_The_Answers()
n = int(input())
g = Graph(n,False)
for i in range(n-1):
u,v = map(int,input().split())
g.addEdge(u-1,v-1)
for i in range(n):
if len(g.graph[i])==1:
leaf = i
break
if not g.bfs(leaf):
print ("NO")
else:
print ("YES")
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
int degree[100005];
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
for (int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
++degree[u];
++degree[v];
}
for (int i = 1; i <= n; ++i) {
if (degree[i] == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const long long max_n = 1e6 + 20;
long long n, m, k, ans, sum;
long long a[max_n];
long long mark[max_n];
vector<long long> v, adj[max_n], jda[max_n];
void dfs(long long v) {
mark[v] = 1;
if (adj[v].size() == 2) ans = -1;
for (auto i : adj[v]) {
if (!mark[i]) {
dfs(i);
}
}
}
int32_t main() {
cin >> n;
for (long long i = 1; i < n; i++) {
long long u, v;
cin >> u >> v;
u--, v--;
adj[v].push_back(u);
adj[u].push_back(v);
}
if (n == 2) {
cout << "YES";
return 0;
}
for (long long i = 0; i < n; i++) {
if (adj[i].size() == 1 && !mark[i]) dfs(i);
}
if (ans == -1) {
cout << "NO";
} else
cout << "YES";
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 10;
int n, u, v;
int a[MAXN];
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n;
memset(a, 0, sizeof(a));
for (int i = 0; i < n - 1; i++) {
cin >> u >> v;
a[u]++;
a[v]++;
}
long long cnt[3] = {0, 0, 0};
for (int i = 1; i <= n; i++) {
if (a[i] <= 2) cnt[a[i]]++;
}
if (cnt[2] == 0 && cnt[1] * (cnt[1] - 1) / 2 >= n - 1)
cout << "YES" << endl;
else
cout << "NO" << endl;
return 0;
}
| 10 | CPP |
n = int(input())
degree = [0 for i in range(n)]
for i in range(n-1):
a = [int(i) for i in input().split()]
x = a[0]-1
y = a[1]-1
degree[x]+=1
degree[y]+=1
flag = 0
for i in range(n):
if(degree[i] == 2):
flag=1
break
if(flag==0):
print("YES")
else:
print("NO") | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
int n, cnt[100009];
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
;
cin >> n;
for (int i = 1; i < n; i++) {
int x, y;
cin >> x >> y;
cnt[x]++, cnt[y]++;
}
for (int i = 1; i <= n; i++)
if (cnt[i] == 2) return cout << "NO", 0;
cout << "YES";
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const long long maxn = 1e5 + 10;
long long n, deg[maxn];
long long read() {
long long x = 0, f = 1;
char ch = getchar();
while (ch < '0' || ch > '9') {
if (ch == '-') f = -1;
ch = getchar();
}
while (ch >= '0' && ch <= '9') {
x = x * 10 + ch - '0';
ch = getchar();
}
return x * f;
}
void print(long long x) {
if (x < 0) putchar('-'), x = -x;
if (x > 9) print(x / 10);
putchar(x % 10 + '0');
}
void write(long long x) {
print(x);
puts("");
}
signed main() {
n = read();
bool flag = 0;
for (long long i = 2; i <= n; i++) deg[read()]++, deg[read()]++;
for (long long i = 1; i <= n; i++)
if (deg[i] == 2) {
puts("NO");
flag = 1;
break;
}
if (!flag) puts("YES");
return 0;
}
| 10 | CPP |
n=int(input())
ar=[0]*n
for i in range(n-1):
a,b=map(int,input().split())
ar[a-1]+=1
ar[b-1]+=1
ans="YES"
for i in range(n):
if(ar[i]==2):
ans="NO"
break
print(ans) | 10 | PYTHON3 |
import sys
input = sys.stdin.readline
def getN():
return int(input())
def getList():
return list(map(int, input().split()))
from sys import exit
n = getN()
vertex = [[] for i in range(n)]
for i in range(n-1):
a, b = getList()
vertex[a-1].append(b-1)
vertex[b - 1].append(a - 1)
for v in vertex:
if len(v) == 2:
print("NO")
exit()
print("YES") | 10 | PYTHON3 |
n = int(input())
# n, k = map(int, input().split())
# a = [int(i) for i in input().split()]
d = [0 for i in range(n + 1)]
for i in range(n - 1):
a, b = map(int, input().split())
d[a] += 1; d[b] += 1
for val in d:
if val == 2:
print("NO")
exit()
print("YES")
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
vector<long long> tree[500500];
long long num[500500], fine = 0, n;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin >> n;
for (int i = 1; i < n; i++) {
long long u, v;
cin >> u >> v;
tree[u].push_back(v);
tree[v].push_back(u);
}
for (int i = 1; i <= n; i++)
if (tree[i].size() == 2) return cout << "NO", 0;
cout << "YES";
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
void solve() {
int n, u, v;
cin >> n;
vector<int> Adj[n];
for (int i = 1; i < n; ++i) {
cin >> u >> v;
--u;
--v;
Adj[u].push_back(v);
Adj[v].push_back(u);
}
for (int i = 0; i < n; ++i) {
if (Adj[i].size() == 2) {
cout << "NO\n";
return;
}
}
cout << "YES\n";
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
while (t--) solve();
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
long long powmod(long long a, long long b) {
long long res = 1;
a %= mod;
assert(b >= 0);
for (; b; b >>= 1) {
if (b & 1) res = res * a % mod;
a = a * a % mod;
}
return res;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
const int maxn = 1e5 + 100;
int n, x;
int a[maxn];
int main(int argc, char const *argv[]) {
ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
cin >> n;
for (int i = 0; i < n - 1; i++) {
cin >> x;
a[x]++;
cin >> x;
a[x]++;
}
for (int i = 1; i < n + 1; i++) {
if (a[i] == 2) {
cout << "No" << endl;
return 0;
}
}
cout << "YES" << endl;
return 0;
}
| 10 | CPP |
n = int(input())
adj = [0 for i in range(n)]
for i in range(n-1):
iarr = list(map(int,input().split()))
u = iarr[0]-1
v = iarr[1]-1
adj[u]+=1
adj[v]+=1
flag = 0
for i in adj:
if i==2:
flag=1
break
if flag==1:
print("NO")
else:
print("YES")
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
int main() {
int n;
cin >> n;
vector<vector<int>> g(n);
int f, t;
for (int i = 0; i < n - 1; ++i) {
cin >> f >> t;
f--;
t--;
g[f].push_back(t);
g[t].push_back(f);
}
for (int i = 0; i < n; ++i) {
if (g[i].size() == 2) {
cout << "NO\n";
return 0;
}
}
cout << "YES\n";
return 0;
}
| 10 | CPP |
n=int(input())
d={}
o,t=0,0
for _ in range(n-1):
s,e=map(int,input().split())
if s in d:
d[s]+=1
else:
d[s]=1
if e in d:
d[e]+=1
else:
d[e]=1
for i in d:
if d[i]==1:
o+=1
elif d[i]==2:
t+=1
if t:
print('NO')
else:
if (o*(o-1))//2>=n-1:
print('YES')
else:
print('NO')
| 10 | PYTHON3 |
from sys import stdin
input = stdin.readline
n = int(input())
degree = [0 for i in range(n+1)]
for _ in range(n-1):
i, j = [int(i) for i in input().split()]
degree[i] += 1
degree[j] += 1
res = False
for i in range(1, n+1):
if degree[i] == 2: res = True
if res: print("NO")
else: print("YES") | 10 | PYTHON3 |
n=int(input())
tree=[[] for i in range(n)]
for i in range(n-1):
u,v=map(int,input().split())
tree[u-1].append(v-1)
tree[v-1].append(u-1)
if n==2:
print("YES")
exit()
#nが4以上
for i in range(n):
if len(tree[i])==2:
print("NO")
break
else:
print("YES") | 10 | PYTHON3 |
if __name__ == '__main__':
n = int(input())
g = [[] for _ in range(n)]
for _ in range(n - 1):
u, v = map(int, input().split())
g[u - 1].append(v - 1)
g[v - 1].append(u - 1)
if list(filter(lambda x: len(x) == 2, g)):
print("NO")
else:
print("YES") | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
int a[N];
int main() {
int n;
scanf("%d", &n);
for (int i = 1; i < n; i++) {
int x, y;
scanf("%d%d", &x, &y);
a[x]++;
a[y]++;
}
for (int i = 1; i <= n; i++)
if (a[i] == 2) {
printf("NO\n");
return 0;
}
printf("YES\n");
return 0;
}
| 10 | CPP |
n = int(input())
a = []
for i in range(0,n+9):
a.append(0)
for i in range(1,n):
u,v = map(int,input().split())
a[u] = a[u]+1
a[v] = a[v]+1
flag = 1;
for i in range(1,n+1):
if a[i]==2:
flag = 0
if flag==0:
print("NO")
else:
print("YES")
| 10 | PYTHON3 |
from collections import defaultdict
g = defaultdict(set)
n = int(input())
for _ in range(n - 1):
u, v = map(int, input().split())
g[u].add(v)
g[v].add(u)
def solve(n, g):
for i in range(1, n + 1):
if len(g[i]) == 1 or len(g[i]) >= 3:
continue
else:
return False
return True
solution = solve(n, g)
print('YES' if solution else 'NO') | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
const long long N = 1e5 + 7;
long long n;
vector<long long> add[N];
void nie() {
cout << "NO";
exit(0);
}
void yie() {
cout << "YES";
exit(0);
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
vector<pair<long long, long long>> v;
cin >> n;
for (long long i = 1; i < n; i++) {
long long x, y;
cin >> x >> y;
add[x].push_back(y);
add[y].push_back(x);
v.push_back({x, y});
}
if (n == 2) yie();
if (n == 3) nie();
for (auto i : v) {
if (add[i.second].size() == 2 || add[i.first].size() == 2) nie();
}
yie();
return 0;
}
| 10 | CPP |
n = int(input())
l = [0 for i in range(n)]
for _ in range(n-1):
a, b = list(map(int, input().split()))
l[a-1] += 1
l[b-1] += 1
for i in range(n):
if (l[i] == 2):
print('NO')
break
else:
print('YES') | 10 | PYTHON3 |
from collections import Counter
from sys import stdin
n=int(input())
lst=[]
for _ in range(n-1):
a,b=map(int,stdin.readline().split())
lst.append(a)
lst.append(b)
fg=0
for _,i in Counter(lst).items():
if i==2:
fg=1
break
if fg==1:
print("NO")
else:
print("YES") | 10 | PYTHON3 |
#include <bits/stdc++.h>
#pragma GCC optimize("-O2")
using namespace std;
const int LIM = 1e5 + 5, MOD = 1e9 + 7;
const long double EPS = 1e-9;
vector<vector<int> > g;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin >> n;
g.resize(n);
for (int i = 0; i < n - 1; ++i) {
int u, v;
cin >> u >> v;
u--, v--;
g[u].push_back(v);
g[v].push_back(u);
}
for (int i = 0; i < n; ++i) {
if (g[i].size() == 2) {
cout << "NO" << '\n';
exit(0);
}
}
cout << "YES" << '\n';
return 0;
}
| 10 | CPP |
n = int(input())
edges = [0]*(n+1)
isPossible = True
for i in range(n-1):
a,b = [int(i) for i in input().split()]
edges[a]+=1
edges[b]+=1
for d in edges:
if d == 2:
isPossible = False
break
print("YES" if isPossible else "NO") | 10 | PYTHON3 |
import sys
N = int(input())
adj_list = [[] for _ in range(N)]
for _ in range(N-1):
(u,v) = list(map(int, input().split()))
u -= 1
v -= 1
adj_list[u].append(v)
adj_list[v].append(u)
num_leaf = 0
for node in range(N):
if len(adj_list[node]) == 2:
print("NO")
sys.exit(0)
print("YES")
| 10 | PYTHON3 |
from sys import stdin
input=stdin.readline
n=int(input())
a=[[] for i in range(n)]
for i in range(n-1):
c,d=map(int,input().split())
a[c-1].append(d-1)
a[d-1].append(c-1)
if n==2:
print('YES')
else:
k=0
for i in a:
if len(i)==2:
exit(print('NO'))
print('YES')
| 10 | PYTHON3 |
# |
# _` | __ \ _` | __| _ \ __ \ _` | _` |
# ( | | | ( | ( ( | | | ( | ( |
# \__,_| _| _| \__,_| \___| \___/ _| _| \__,_| \__,_|
import sys
import math
def read_line():
return sys.stdin.readline()[:-1]
def read_int():
return int(sys.stdin.readline())
def read_int_line():
return [int(v) for v in sys.stdin.readline().split()]
def read_float_line():
return [float(v) for v in sys.stdin.readline().split()]
n = read_int()
d = {}
for i in range(n-1):
u, v = read_int_line()
if u in d:
d[u] += 1
else:
d[u] = 1
if v in d:
d[v] += 1
else:
d[v] = 1
f = False
for i in d:
if d[i]==2:
f = True
if f:
print("NO")
else:
print("YES")
| 10 | PYTHON3 |
def ii():
return int(input())
def ss():
return [x for x in input()]
def si():
return [int(x) for x in input().split()]
def mi():
return map(int, input().split())
a = ii()
s = [0 for i in range(a)]
for i in range(a - 1):
c, d = [int(x) - 1 for x in input().split()]
s[c] += 1
s[d] += 1
if 2 in s:
print("NO")
else:
print("YES") | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
void func() {
int n;
cin >> n;
vector<int> adj[n + 1];
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
for (int i = 1; i <= n; i++) {
if (adj[i].size() == 1) continue;
if (adj[i].size() < 3) {
cout << "NO" << endl;
return;
}
}
cout << "YES" << endl;
return;
}
int main() {
std::ios::sync_with_stdio(false);
int t = 1;
while (t--) func();
return 0;
}
| 10 | CPP |
import sys
input=sys.stdin.readline
from collections import deque
n=int(input())
if n==2:
print('YES')
exit()
if n==3:
print('NO')
exit()
Edges=[[] for _ in range(n)]
for _ in range(n-1):
u,v=map(lambda x: int(x)-1,input().split())
Edges[u].append(v)
Edges[v].append(u)
for i,E in enumerate(Edges):
if len(E)>=3:
root=i
break
else:
print('NO')
exit()
Chi=[[] for _ in range(n)]
Par=[0]*n
q=deque()
q.append(root)
Used=[False]*n
Used[root]=True
while q:
v=q.popleft()
for c in Edges[v]:
if Used[c]:
continue
Chi[v].append(c)
Par[c]=v
Used[c]=True
q.append(c)
Leaf=[]
for v,l in enumerate(Chi):
if not l:
Leaf.append(v)
for l in Leaf:
while True:
p=Par[l]
if p==root:
break
if len(Chi[p])==1:
print('NO')
exit()
l=p
print('YES') | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
const long long MAX = 1e5 + 10;
long long arr[MAX];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
arr[u]++;
arr[v]++;
}
for (int i = 1; i <= n; i++)
if (arr[i] == 2) return puts("NO");
puts("YES");
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
const int N = 3e5 + 5, M = 1e8 + 5, OO = 1000000;
int T, n, m;
int u, v;
int deg[N];
int main() {
scanf("%d", &n);
for (int i = 1; i < n; ++i) {
scanf("%d %d", &u, &v);
++deg[u], ++deg[v];
}
for (int i = 1; i <= n; ++i) {
if (deg[i] == 2) {
printf("NO\n");
return 0;
}
}
printf("YES\n");
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int a[100010];
int main() {
int n, flag = 1;
scanf("%d", &n);
for (int i = 1, x, y; i < n; i++) {
scanf("%d %d", &x, &y);
a[x]++;
a[y]++;
}
for (int i = 1; i <= n; i++)
if (a[i] == 2) flag = 0;
flag ? printf("YES") : printf("NO");
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int deg[100005];
int main() {
int n;
scanf("%d", &n);
for (int i = 1; i < n; i++) {
int u, v;
scanf("%d%d", &u, &v);
deg[u]++;
deg[v]++;
}
for (int i = 1; i <= n; i++) {
if (deg[i] == 2) {
printf("NO\n");
return 0;
}
}
printf("YES\n");
return 0;
}
| 10 | CPP |
n = int(input())
nodes = [[] for _ in range(n)]
edges = []
for _ in range(n-1):
u, v = sorted(map(int, input().split(" ")))
u -= 1
v -= 1
nodes[u].append(v)
nodes[v].append(u)
edge = [u, v]
edges.append(edge)
leaf_nodes = [node for node in nodes if len(node) == 1]
num_ads = [len(node) for node in nodes]
if 2 in num_ads:
out = "NO"
else:
out = "YES"
#print(num_ads)
#for u, v in edges:
# num_ad_u = num_ads[u]
# num_ad_v = num_ads[v]
# #if num_ad_u == 1 or num_ad_v == 1:
# # continue
# if num_ad_u == 2 or num_ad_v == 2:
# out = "NO"
# break
print(out) | 10 | PYTHON3 |
from collections import defaultdict
n = int(input())
hash = defaultdict(list)
for i in range(n-1):
a,b = map(int,input().split())
hash[a].append(b)
hash[b].append(a)
flag = 1
for i in hash.keys():
if len(hash[i]) == 2:
flag = 0
break
if flag:
print('YES')
else:
print('NO')
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using ll = int64_t;
using namespace std;
const int N = 1e6 + 5;
int n;
int a[N];
basic_string<int> g[N];
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for (int i = 1, u, v; i < n; i++) {
cin >> u >> v;
g[u] += v;
g[v] += u;
}
for (int i = 1; i <= n; i++) {
if (g[i].size() == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int n;
int n1, n2;
int grau[100010];
vector<pair<int, int> > edges;
int main() {
scanf("%d", &n);
for (int g = 0; g < n - 1; g++) {
scanf("%d %d", &n1, &n2);
grau[n1]++;
grau[n2]++;
}
for (int g = 1; g <= n; g++) {
if (grau[g] == 2) {
printf("NO\n");
return 0;
}
}
printf("YES\n");
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1};
int dy8[] = {0, 1, 1, 1, 0, -1, -1, -1};
int dx4[] = {1, 0, -1, 0};
int dy4[] = {0, 1, 0, -1};
template <class A, class B>
ostream& operator<<(ostream& out, const pair<A, B>& a) {
return out << "(" << a.first << "," << a.second << ")";
}
template <class A>
ostream& operator<<(ostream& out, const vector<A>& a) {
for (const A& it : a) out << it << " ";
return out;
}
template <class A, class B>
istream& operator>>(istream& in, pair<A, B>& a) {
return in >> a.first >> a.second;
}
template <class A>
istream& operator>>(istream& in, vector<A>& a) {
for (A& i : a) in >> i;
return in;
}
vector<int>* inputG(int n, int m) {
vector<int>* edges = new vector<int>[n + 1];
for (int i = 0; i < m; i++) {
int sv, ev;
cin >> sv >> ev;
edges[sv].push_back(ev);
edges[ev].push_back(sv);
}
return edges;
}
void solve() {
int n;
cin >> n;
vector<int>* edges = inputG(n, n - 1);
for (int i = 1; i <= n; i++) {
if (edges[i].size() == 2) {
cout << "NO"
<< "\n";
;
return;
}
}
cout << "YES"
<< "\n";
;
}
int main() {
ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
int t = 1;
while (t--) {
solve();
}
return 0;
}
| 10 | CPP |
import sys
input = sys.stdin.readline
n = int(input())
a = [list(map(int, input().split())) for i in range(n-1)]
tree = [[] for i in range(n)]
for i in range(n - 1):
tree[a[i][0] - 1].append(a[i][1] - 1)
tree[a[i][1] - 1].append(a[i][0] - 1)
for i in range(n):
if len(tree[i]) == 2:
print("NO")
exit()
print("YES")
| 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
int deg[200000];
int main() {
int n;
cin >> n;
for (int i = 0; i < n - 1; ++i) {
int u, v;
cin >> u >> v;
deg[u]++;
deg[v]++;
}
for (int i = 1; i <= n; ++i) {
if (deg[i] == 2) {
cout << "NO\n";
return 0;
}
}
cout << "YES\n";
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
int main() {
int x, y, n;
cin >> n;
vector<int> v[100010], barg;
for (int i = 0; i < n - 1; i++) {
cin >> x >> y;
v[x].push_back(y);
v[y].push_back(x);
}
for (int i = 1; i <= n; i++) {
if (v[i].size() == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 1000, mod = 1e9 + 7;
vector<int> vec[N];
long long bin_pow(int x, int y) {
if (y == 0) return 1;
if (y == 1) return x;
if (y % 2 == 0) {
long long z = bin_pow(x, y / 2);
return (z * z) % mod;
}
return (bin_pow(x, y - 1) * x) % mod;
}
bool check(int x) {}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n;
cin >> n;
for (int i = 1; i < n; i++) {
int x, y;
cin >> x >> y;
vec[x].push_back(y);
vec[y].push_back(x);
}
int k = 0;
for (int i = 1; i <= n; i++) {
if (vec[i].size() == 2) {
cout << "NO";
return 0;
}
}
cout << "YES";
return 0;
}
| 10 | CPP |
#include <bits/stdc++.h>
using namespace std;
vector<vector<long long> > g;
void endProg() {
cout << "NO";
exit(0);
}
void dfs(long long v, long long p) {
long long l = 0;
for (auto i : g[v]) {
if (i == p) continue;
if (g[i].size() == 1) {
l++;
continue;
}
dfs(i, v);
}
if (v == 0) {
if (g[v].size() == 2) endProg();
} else {
if (g[v].size() == 2) endProg();
}
}
int main() {
long long n;
cin >> n;
g.resize(n);
for (long long i = 0; i < n - 1; i++) {
long long a, b;
cin >> a >> b;
g[a - 1].push_back(b - 1);
g[b - 1].push_back(a - 1);
}
dfs(0, 0);
cout << "YES";
return 0;
}
| 10 | CPP |
import sys
num = int(input())
deg = [0]*(num+1)
for _ in range(1,num):
a, b = [int(i) for i in input().split()]
deg[a ] += 1
deg[b] += 1
for i in range(1, num+1):
if deg[i] == 2:
print("NO")
sys.exit()
print("YES") | 10 | PYTHON3 |
# -*- coding: utf-8 -*-
import sys
# from operator import itemgetter
# from fractions import gcd
# from math import ceil, floor
# from copy import deepcopy
# from itertools import accumulate
from collections import deque
# import math
# from functools import reduce
input = sys.stdin.readline
def ii(): return int(input())
def mi(): return map(int, input().rstrip().split())
def lmi(): return list(map(int, input().rstrip().split()))
def li(): return list(input().rstrip())
# template
# BEGIN CUT HERE
class Graph():
def __init__(self, n, Weighted=False, Directed=True, Matrix=False):
self.sz = n
self.is_Weighted = Weighted
self.is_Directed = Directed
self.is_Matrix = Matrix
if Matrix:
if Weighted:
self.graph = [[0 for _i in range(n)] for _j in range(n)]
else:
self.graph = [[0 for _i in range(n)] for _j in range(n)]
else:
self.graph = [[] for _i in range(n)]
def _weighted_add_edge(self, x, y, w):
if self.is_Matrix:
self.graph[x][y] = w
else:
self.graph[x].append((y, w))
def _unweighted_add_edge(self, x, y):
if self.is_Matrix:
self.graph[x][y] = 1
else:
self.graph[x].append(y)
def add_edge(self, x, y, *w):
if self.is_Directed:
if self.is_Weighted:
self._weighted_add_edge(x, y, w[0])
else:
self._unweighted_add_edge(x, y)
else:
if self.is_Weighted:
self._weighted_add_edge(x, y, w[0])
self._weighted_add_edge(y, x, w[0])
else:
self._unweighted_add_edge(x, y)
self._unweighted_add_edge(y, x)
def _convert_to_maxrix(self):
if self.is_Matrix:
return self
mat_g = self.__class__(
self.sz, Weighted=self.is_Weighted, Directed=self.is_Directed, Matrix=True)
if self.is_Weighted:
for i in range(self.sz):
for j in self.graph[i]:
mat_g.add_edge(i, j[0], j[1])
else:
for i in range(self.sz):
for j in self.graph[i]:
mat_g.add_edge(i, j)
return mat_g
def __getitem__(self, n):
return self.graph[n]
# def __setitem__(self, n, v):
# if not self.is_Weighted and not self.is_Matrix:
# self.graph[n] = v
def __str__(self):
return str([self.graph[i] for i in range(self.sz)])
def main():
n = ii()
g = Graph(n, Directed=False)
for i in range(n - 1):
s, t = mi()
g.add_edge(s-1, t-1)
for i in range(n):
if len(g[i]) == 2:
break
else:
print('YES')
sys.exit()
print('NO')
if __name__ == '__main__':
main()
| 10 | PYTHON3 |
from collections import defaultdict
n = int(input())
tr = defaultdict(int)
for i in range(n-1):
u, v = map(int, input().split())
tr[u]+=1
tr[v]+=1
for i in tr:
if tr[i]==2:
print("NO")
break
else:
print("YES") | 10 | PYTHON3 |
#include <bits/stdc++.h>
using namespace std;
const long long inf = LONG_MAX;
const long long arr = 1000000;
bool comp(pair<long long, long long> a, pair<long long, long long> b) {
if (a.first == b.first)
return a.second < b.second;
else
return a.first < b.first;
}
vector<vector<long long> > g(arr);
int main(void) {
long long n;
cin >> n;
for (int i = 0; i < n - 1; i++) {
long long l, r;
cin >> l >> r;
g[l].push_back(r);
g[r].push_back(l);
}
for (long long i = 1; i <= n; i++) {
if (g[i].size() == 2) return cout << "NO" << '\n', 0;
}
cout << "YES" << '\n';
return 0;
}
| 10 | CPP |
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