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OI-codes/AtCoder/ABC259/F/F.cpp

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#include <iostream>
#include <algorithm>
#include <functional>
#include <limits>
#include <utility>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 3e5 + 5;
int n, d[N];
long long f[N][2];
std::vector<std::pair<int, int>> g[N];
void dfs(int u, int fa) {
std::vector<long long> weights;
for (auto e : g[u]) {
int v = e.first,
w = e.second;
if (v == fa) continue;
dfs(v, u);
weights.push_back(f[v][0] + w - f[v][1]);
f[u][0] += f[v][1];
f[u][1] += f[v][1];
}
std::sort(weights.begin(), weights.end(), std::greater<>());
for (int i = 0; i < weights.size(); i++) {
if (weights[i] <= 0) break;
if (i < d[u] - 1) f[u][0] += weights[i];
if (i < d[u]) f[u][1] += weights[i];
}
if (!d[u]) f[u][0] = std::numeric_limits<int>::min();
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> d[i];
}
for (int i = 1, u, v, w; i < n; i++) {
cin >> u >> v >> w;
g[u].emplace_back(v, w);
g[v].emplace_back(u, w);
}
dfs(1, 0);
cout << f[1][1] << endl;
return 0;
}