Submission #1173358

#	Time	Username	Problem	Language	Result	Execution time	Memory
1173358		Muhammet	Duathlon (APIO18_duathlon)	C++20	0 / 100	1088 ms	424540 KiB

count_triplets

#include "bits/stdc++.h"

using namespace std;
 
#define ll long long
#define SZ(s) (int)s.size()

const int N = 2e5 + 5;
const int M = 1e9 + 7;

int n, m;

ll ans;

vector <int> v[N];

void dfs(int x, int y, ll cnt) {
    ans += max(0LL, ((cnt - 2) * (cnt - 1)) / 2);
    for(auto i : v[x]) {
        if(i != y) dfs(i, x, cnt+1);
    }
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);

    cin >> n >> m;
    for(int i = 1; i <= m; i++) {
        int u1, u2;
        cin >> u1 >> u2;
        v[u1].push_back(u2);
        v[u2].push_back(u1);
    }

    int k;
    for(int i = 1; i <= n; i++) {
        if(SZ(v[i]) < 2) k = i;
    }

    dfs(k, 0, 1);

    cout << ans * 2;

    return 0;
}

• 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