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49 lines
1.2 KiB
49 lines
1.2 KiB
2 years ago
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#include <bits/stdc++.h>
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using namespace std;
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const int N = 1e5 + 100;
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#define int long long
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#define endl "\n"
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int f[N], sz[N], dis[N], c[N];
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struct edge {
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int to, w;
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};
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vector<edge> g[N];
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void dfs1(int u, int fa) {
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sz[u] = c[u];
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for (int i = 0; i < g[u].size(); i++) {
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int v = g[u][i].to;
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if (v == fa) continue;
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dis[v] = dis[u] + g[u][i].w; // 每个点到根节点的距离
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dfs1(v, u);
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sz[u] += sz[v]; // 以u为根的子树奶牛数量
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}
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}
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void dfs2(int u, int fa) {
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for (int i = 0; i < g[u].size(); i++) {
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int v = g[u][i].to;
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if (v == fa) continue;
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f[v] = f[u] + (sz[1] - 2 * sz[v]) * g[u][i].w;
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dfs2(v, u);
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}
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}
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signed main() {
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int n;
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cin >> n;
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for (int i = 1; i <= n; i++) cin >> c[i];
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for (int i = 1; i < n; i++) {
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int u, v, w;
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cin >> u >> v >> w;
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g[u].push_back({v, w});
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g[v].push_back({u, w});
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}
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dfs1(1, -1);
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for (int i = 2; i <= n; i++) f[1] += dis[i] * c[i];
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dfs2(1, -1);
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int ans = 1e18;
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for (int i = 1; i <= n; i++) ans = min(ans, f[i]);
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cout << ans << endl;
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}
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