func_code_string: #include <bits/stdc++.h>   using namespace std;   const int mod = 1e9 + 7;   struct Node {     int cnt, l, r, z_0, z_1;     Node() {       cnt = 0;       l = r = -1;       z_0 = z_1 = 0;     }   };   vector<Node> Trie;   void update(int x) {     int cur = 0;     for (int i = 30; i >= 0; i--) {       int c = (((1 << i) & x) > 0);       if (Trie[cur].l == -1) {         Trie.push_back(Node());         Trie[cur].l = Trie.size() - 1;       }       if (Trie[cur].r == -1) {         Trie.push_back(Node());         Trie[cur].r = Trie.size() - 1;       }       if (!c)         cur = Trie[cur].l;       else         cur = Trie[cur].r;       Trie[cur].cnt++;     }   }   int query(int x, int k) {     int ans = 0, cur = 0;     for (int i = 30; i >= 0; i--) {       int c_x = (((1 << i) & x) > 0);       int c_k = (((1 << i) & k) > 0);       if (Trie[cur].l == -1) {         Trie.push_back(Node());         Trie[cur].l = Trie.size() - 1;       }       if (Trie[cur].r == -1) {         Trie.push_back(Node());         Trie[cur].r = Trie.size() - 1;       }       if (!c_x) {         if (!c_k) {           ans += Trie[Trie[cur].r].cnt;           cur = Trie[cur].l;         } else           cur = Trie[cur].r;       } else {         if (!c_k) {           ans += Trie[Trie[cur].l].cnt;           cur = Trie[cur].r;         } else           cur = Trie[cur].l;       }     }     ans += Trie[cur].cnt;     return ans;   }   void update2(int x, int col) {     int cur = 0;     for (int i = 30; i >= 0; i--) {       int c = (((1 << i) & x) > 0);       if (Trie[cur].l == -1) {         Trie.push_back(Node());         Trie[cur].l = Trie.size() - 1;       }       if (Trie[cur].r == -1) {         Trie.push_back(Node());         Trie[cur].r = Trie.size() - 1;       }       if (!c)         cur = Trie[cur].l;       else         cur = Trie[cur].r;       if (col == 1)         Trie[cur].z_1++;       else         Trie[cur].z_0++;     }   }   long long query2(int x, int k, int col) {     long long ans = 0;     int cur = 0;     for (int i = 30; i >= 0; i--) {       int c_x = (((1 << i) & x) > 0);       int c_k = (((1 << i) & k) > 0);       if (Trie[cur].l == -1) {         Trie.push_back(Node());         Trie[cur].l = Trie.size() - 1;       }       if (Trie[cur].r == -1) {         Trie.push_back(Node());         Trie[cur].r = Trie.size() - 1;       }       if (!c_x) {         if (!c_k) {           if (col == 1)             ans += Trie[Trie[cur].r].z_1;           else             ans += Trie[Trie[cur].r].z_0;           cur = Trie[cur].l;         } else           cur = Trie[cur].r;       } else {         if (!c_k) {           if (col == 1)             ans += Trie[Trie[cur].l].z_1;           else             ans += Trie[Trie[cur].l].z_0;           cur = Trie[cur].r;         } else           cur = Trie[cur].l;       }     }     if (col == 1)       ans += Trie[cur].z_1;     else       ans += Trie[cur].z_0;     return ans;   }   int n, m;   int a[50001];   int check(int x) {     Trie.clear();     Trie.push_back(Node());     int cnt = 0;     for (int i = 1; i <= n; i++) {       cnt += query(a[i], x);       update(a[i]);     }     return cnt;   }   int32_t main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     cin >> n >> m;     if (m == 0) {       cout << 0;       return 0;     }     for (int i = 1; i <= n; i++) cin >> a[i];     long long l = 0, r = 2e9;     int ans = -1;     while (l <= r) {       long long mi = (l + r) / 2;       if (check(mi) >= m) {         ans = mi;         l = mi + 1;       } else         r = mi - 1;     }     int lft = check(ans) - m;     long long res = 0;     for (int j = 0; j <= 30; j++) {       Trie.clear();       Trie.push_back(Node());       for (int i = 1; i <= n; i++) {         int c = (((1 << j) & a[i]) > 0);         res = (res + (query2(a[i], ans, 1 - c) * (1LL << j)) % mod) % mod;         update2(a[i], c);       }     }     cout << ((res - lft * ans) % mod + mod) % mod;   }   