Submission #1115810

#	Time	Username	Problem	Language	Result	Execution time	Memory
1115810		gustavo_d	Duathlon (APIO18_duathlon)	C++17	23 / 100	1094 ms	1048576 KiB

count_triplets

// https://oj.uz/problem/view/APIO18_duathlon > p520
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
const int MAXN = 1e5;
vector<int> adj[MAXN];
ll sz[MAXN]; ll sum_dist[MAXN];
bool vis[MAXN];
ll ans = 0;

void dfs(int v, int pai) {
	vis[v] = true;
	sz[v] = 1; sum_dist[v] = 0;
	for (int viz : adj[v]) {
		if (viz == pai) continue;
		dfs(viz, v);
		sz[v] += sz[viz];
		sum_dist[v] += sum_dist[viz] + sz[viz];
	}

	ll add = 0;
	for (int viz : adj[v]) {
		if (viz == pai) continue;
		ans += 2LL*sum_dist[viz]; // lca sendo ponta
		ans += 2LL*sum_dist[viz] * (sz[v] - sz[viz] - 1LL);
		add += 2LL*sz[viz] * (sz[v] - sz[viz] - 1LL);
	}
	ans += add / 2;
}

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

	int n, m; cin >> n >> m;
	for (int i=0; i<m; i++) {
		int u, v; cin >> u >> v;
		u--; v--;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	for (int i=0; i<n; i++) {
		if (vis[i]) continue;
		dfs(i, -1);
	}
	cout << ans << '\n';

	return 0;
}

• 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