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mirror of https://git.sb/baoshuo/OI-codes.git synced 2024-11-27 14:56:27 +00:00

P2458 [SDOI2006]保安站岗

https://www.luogu.com.cn/record/86522118
This commit is contained in:
Baoshuo Ren 2022-09-13 11:42:09 +08:00
parent 5960485241
commit 0b2d1d4c45
Signed by: baoshuo
GPG Key ID: 00CB9680AB29F51A

59
Luogu/P2458/P2458.cpp Normal file
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#include <iostream>
#include <algorithm>
#include <compare>
#include <limits>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1505;
int n, a[N], f[N][3];
std::vector<int> g[N];
void dfs(int u, int fa) {
f[u][2] = a[u];
for (int v : g[u]) {
if (v == fa) continue;
dfs(v, u);
f[u][0] += std::min(f[v][1], f[v][2]);
f[u][2] += std::min({f[v][0], f[v][1], f[v][2]});
}
f[u][1] = std::numeric_limits<int>::max();
for (int v : g[u]) {
if (v == fa) continue;
f[u][1] = std::min(f[u][1], f[u][0] - std::min(f[v][1], f[v][2]) + f[v][2]);
}
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 1, u, v, m; i <= n; i++) {
cin >> u >> a[u] >> m;
while (m--) {
cin >> v;
g[u].emplace_back(v);
g[v].emplace_back(u);
}
}
dfs(1, 0);
cout << std::min(f[1][1], f[1][2]) << endl;
return 0;
}