Tietoverkko

#include <iostream>
#include <vector>
using namespace std;

const int N = 200001;

int n;
long r;
vector<pair<int, int>> g[N];

int dfs(int s, int e) {
	int sz = 1;
	for (auto [u, w] : g[s]) {
		if (u != e) {
			int z = dfs(u, s);
			r += 1ll * z * (n - z) * w;
			sz += z;
		}
	}
	return sz;
}

int main() {
	cin >> n;

	for (int i = 0; i < n - 1; ++i) {
		int a, b, x;
		cin >> a >> b >> x;
		g[a].emplace_back(b, x);
		g[b].emplace_back(a, x);
	}

	dfs(1, 1);

	cout << r / 2 << endl;
}

Test 1

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 2

Group: 2, 3

Verdict: WRONG ANSWER

Test 3

Group: 3

Verdict: WRONG ANSWER