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https://git.sb/baoshuo/OI-codes.git
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82 lines
1.3 KiB
C++
82 lines
1.3 KiB
C++
#include <iostream>
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#include <vector>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 1e5 + 5;
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int n, sum, root, c[N], siz[N], max_siz[N], dep[N];
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long long ans;
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std::vector<std::pair<int, int>> g[N];
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void dfs1(int u, int f) {
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siz[u] = c[u];
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for (auto e : g[u]) {
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int v = e.first,
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w = e.second;
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if (v == f) continue;
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dfs1(v, u);
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siz[u] += siz[v];
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max_siz[u] = std::max(max_siz[u], siz[v]);
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}
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max_siz[u] = std::max(max_siz[u], sum - siz[u]);
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}
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void dfs2(int u, int f) {
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for (auto e : g[u]) {
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int v = e.first,
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w = e.second;
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if (v == f) continue;
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dep[v] = dep[u] + w;
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dfs2(v, u);
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}
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n;
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for (int i = 1; i <= n; i++) {
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cin >> c[i];
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sum += c[i];
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}
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for (int i = 1, u, v, w; i <= n; i++) {
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cin >> u >> v >> w;
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g[u].emplace_back(v, w);
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g[v].emplace_back(u, w);
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}
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dfs1(1, 0);
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for (int i = 1; i <= n; i++) {
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if (!root || max_siz[i] < max_siz[root]) {
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root = i;
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}
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}
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dep[0] = -1;
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dfs2(root, 0);
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for (int i = 1; i <= n; i++) {
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ans += static_cast<long long>(c[i]) * dep[i];
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}
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cout << ans << endl;
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return 0;
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}
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