python/TangDou/Topic/HuanGenDp/POJ3585.cpp

#include <iostream>
#include <cstdio>
#include <vector>
#include <cstring>
using namespace std;
const int N = 2e5 + 10;
int T, n, du[N];

struct node {
    int to, w;
};
vector<node> c[N];

bool v[N];
int d[N], f[N];

void clean() {
    memset(v, 0, sizeof v);
    memset(du, 0, sizeof du);
    memset(d, 0, sizeof d);
    memset(f, 0, sizeof f);

    for (int i = 1; i <= n; i++) c[i].clear();
}
void dp(int x) {
    v[x] = 1;
    int size = c[x].size() - 1;
    for (int i = 0; i <= size; i++) {
        int to = c[x][i].to, w = c[x][i].w;
        if (v[to]) continue;
        dp(to);
        if (du[to] == 1)
            d[x] += w;
        else
            d[x] += min(d[to], w);
    }
    return;
}
void dfs(int x) {
    v[x] = 1;
    int size = c[x].size() - 1;
    for (int i = 0; i <= size; i++) {
        int to = c[x][i].to, w = c[x][i].w;
        if (v[to]) continue;
        if (du[x] == 1)
            f[to] = d[to] + w;
        else
            f[to] = d[to] + min(f[x] - min(d[to], w), w);
        dfs(to);
    }
    return;
}

int main() {
    cin >> T;
    while (T--) {
        cin >> n;
        clean();
        int x, y, z;
        for (int i = 1; i < n; i++) {
            cin >> x >> y >> z;
            c[x].push_back((node){y, z});
            c[y].push_back((node){x, z});
            du[x]++;
            du[y]++;
        }
        dp(1);
        f[1] = d[1];
        memset(v, 0, sizeof v);
        dfs(1);
        int ans = 0;
        for (int i = 1; i <= n; i++) ans = max(ans, f[i]);
        printf("%d\n", ans);
    }
    return 0;
}