Submission #1353549

#	Time	Username	Problem	Language	Result	Execution time	Memory
1353549		DanerZein	Duathlon (APIO18_duathlon)	C++20	23 / 100	1116 ms	1114112 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;

typedef vector<int> vi;
typedef long long ll;
const int MAX_N=1e5+10;

vector<vi> G;

ll sub[MAX_N];
int pa[MAX_N],ro[MAX_N];
int n;
ll res=0;
  
void dfs(int u,int p,int root){
  sub[u]=1;
  pa[u]=p;
  ro[u]=root;
  for(auto &v:G[u]){
    if(v!=p){
      dfs(v,u,root);
      sub[u]+=sub[v];
    }
  }
}

int main(){
  int m; cin>>n>>m;
  G.resize(n);
  for(int i=0;i<m;i++){
    int a,b; cin>>a>>b;
    a--; b--;
    G[a].push_back(b);
    G[b].push_back(a);
  }
  
  for(int i=0;i<n;i++)
    if(sub[i]==0)
      dfs(i,i,i);

  for(int i=0;i<n;i++){
    for(auto &v:G[i]){
      if(v!=pa[i]){
	res+=sub[v]*(sub[i]-sub[v]-1);
	res+=2LL*sub[v]*(sub[ro[i]]-sub[i]);
      }
    }
  }
  
  cout<<res<<endl;
}

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