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| #include <bits/stdc++.h>
using namespace std;
using LL = long long;
const int N = 1e5 + 1, M = 2 * N;
int n, u, v, ww;
int c[N], h[N], w[M], e[M], ne[M], idx;
LL dist[N], sz[N], ans;
void add(int u, int v, int ww) {
e[++idx] = v, w[idx] = ww, ne[idx] = h[u], h[u] = idx;
}
int main() {
scanf("%d", &n);
for (int i = 1; i <= n; ++i) scanf("%d", &c[i]);
for (int i = 1; i < n; ++i) {
scanf("%d%d%d", &u, &v, &ww);
add(u, v, ww), add(v, u, ww);
}
function<LL(int, int)> dfs = [&](int u, int f) {
LL cnt = c[u];
for (int i = h[u]; i; i = ne[i]) {
int v = e[i];
if (v != f) {
LL s = dfs(v, u);
dist[u] += dist[v] + w[i] * s;
cnt += s;
}
}
return sz[u] = cnt;
};
dfs(1, 0);
ans = dist[1];
function<void(int, int)> dp = [&](int u, int f) {
for (int i = h[u]; i; i = ne[i]) {
int v = e[i];
if (v != f) {
dist[v] = dist[u] + (sz[1] - sz[v] - sz[v]) * w[i];
ans = min(ans, dist[v]);
dp(v, u);
}
}
};
dp(1, 0);
printf("%lld\n", ans);
return 0;
}
|