Submission #569111

#	Time	Username	Problem	Language	Result	Execution time	Memory
569111		SSRS	Duathlon (APIO18_duathlon)	C++14	0 / 100	1111 ms	386732 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
int main(){
  int n, m;
  cin >> n >> m;
  vector<vector<int>> E(n);
  for (int i = 0; i < m; i++){
    int u, v;
    cin >> u >> v;
    u--;
    v--;
    E[u].push_back(v);
    E[v].push_back(u);
  }
  vector<int> p(n, -1);
  vector<vector<int>> c(n);
  vector<int> r(n);
  vector<int> bfs;
  for (int i = 0; i < n; i++){
    if (p[i] == -1){
      queue<int> Q;
      Q.push(i);
      while (!Q.empty()){
        int v = Q.front();
        Q.pop();
        bfs.push_back(v);
        r[v] = i;
        for (int w : E[v]){
          if (w != p[v]){
            p[w] = v;
            c[v].push_back(w);
            Q.push(w);
          }
        }
      }
    }
  }
  reverse(bfs.begin(), bfs.end());
  vector<int> dp(n, 1);
  for (int v : bfs){
    for (int w : c[v]){
      dp[v] += dp[w];
    }
  }
  long long ans = 0;
  for (int v = 0; v < n; v++){
    ans += (long long) (dp[r[v]] - 1) * (dp[r[v]] - 2);
    for (int w : c[v]){
      ans -= (long long) dp[w] * (dp[w] - 1);
    }
    ans -= (long long) (n - dp[v]) * (n - dp[v] - 1);
  }
  cout << ans << endl;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10