Tietoverkko

input/code.cpp: In function 'll dfs(int, int)':
input/code.cpp:40:17: warning: unused variable 'w' [-Wunused-variable]
  for (auto [y, w] : adj[x]) {
                 ^

#include <iostream>
#include <set>
#include <queue>
#include <tuple>

using namespace std;
using ll = long long;

set<pair<int, int>> adj[200200];
priority_queue<tuple<int, int, int>> q;

ll dfs(int x, int e);

int main()
{
	int n;
	cin >> n;
	for (int i = 1; i < n; ++i) {
		int a, b, x;
		cin >> a >> b >> x;
		adj[a].emplace(b, x);
		adj[b].emplace(a, x);
		q.emplace(-x, a, b);
	}
	ll s = 0;
	while (!q.empty()) {
		auto [x, a, b] = q.top();
		x = -x;
		q.pop();
		adj[a].erase({b, x});
		adj[b].erase({a, x});
		s += dfs(a, b) * dfs(b, a) * x;
	}
	cout << s << endl;
}

ll dfs(int x, int e)
{
	int k = 1;
	for (auto [y, w] : adj[x]) {
		if (y == e) continue;
		k += dfs(y, x);
	}
	return k;
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: TIME LIMIT EXCEEDED