mirror of
https://git.sb/baoshuo/OI-codes.git
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86 lines
1.7 KiB
C++
86 lines
1.7 KiB
C++
#include <iostream>
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#include <algorithm>
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#include <cmath>
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#include <functional>
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#include <limits>
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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 = 5e5 + 5;
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const long long INF = 1e18;
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int n, m, w[N];
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long long f[N][2];
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std::vector<int> g[N];
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void dfs(int u, int fa) {
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int k = g[u].size() / 2 + 1;
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long long res = 0;
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std::vector<long long> a;
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for (int v : g[u]) {
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if (v == fa) continue;
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dfs(v, u);
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if (w[v] <= w[u]) {
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a.emplace_back(std::max(f[v][0] + w[v], f[v][1] + w[u]) - f[v][1] - m);
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res += f[v][1] + m;
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} else {
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a.emplace_back(f[v][0] + w[u] - std::max(f[v][0] + w[v], f[v][1] + m));
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res += std::max(f[v][0] + w[v], f[v][1] + m);
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}
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}
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std::sort(a.begin(), a.end(), std::greater<>());
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if (k - 1 > a.size()) {
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f[u][0] = -INF;
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} else {
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long long sum = res;
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for (int i = 0; i < k - 1; i++) sum += a[i];
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for (int i = k - 1; i < a.size(); i++) sum += std::max(0ll, a[i]);
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f[u][0] = sum;
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}
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if (k > a.size()) {
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f[u][1] = -INF;
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} else {
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long long sum = res;
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for (int i = 0; i < k; i++) sum += a[i];
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for (int i = k; i < a.size(); i++) sum += std::max(0ll, a[i]);
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f[u][1] = sum;
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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 >> m;
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for (int i = 1; i <= n; i++) {
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cin >> w[i];
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}
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for (int i = 1, u, v; i < n; i++) {
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cin >> u >> v;
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g[u].emplace_back(v);
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g[v].emplace_back(u);
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}
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dfs(1, 1);
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cout << f[1][1] << endl;
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return 0;
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}
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