Submission #103541

#	Time	Username	Problem	Language	Result	Execution time	Memory
103541		Hideo	Duathlon (APIO18_duathlon)	C++14	0 / 100	138 ms	8680 KiB

count_triplets

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

#define ll long long
#define mk make_pair
#define pb push_back
#define fr first
#define sc second
#define vi vector < int >
#define pii pair < int, int >

const int N = 2e5 + 7;
const int INF = 1e9 + 7;

int sz[N];
int n, m;
ll ans;

vi g[N];

void dfs (int v = 1, int p = 0){
    sz[v] = 1;
    for (int to : g[v]){
        if (to != p){
            dfs(to, v);
            sz[v] += sz[to];
        }
    }

}

main(){
    cin >> n >> m;
    for (int i = 1; i <= m; i++){
        int a, b;
        cin >> a >> b;
        g[a].pb(b);
        g[b].pb(a);
    }
    if (m == n - 1){
        dfs();
        for (int i = 2; i <= n; i++){
            ans += sz[i] * (n - sz[i]);
        }
        cout << (ll) ans * 2 - n * (n - 1);
    }
    else {
        cout << 0;
    }
}

Compilation message (stderr)

count_triplets.cpp:32:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^

• 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