python/TangDou/Topic/HuanGenDp/1073_1.cpp

#include <bits/stdc++.h>
using namespace std;

const int INF = 0x3f3f3f3f;
const int N = 10010, M = N << 1;
int n;
int ans;
int res = INF;

// 邻接表
int e[M], h[N], idx, w[M], ne[M];
void add(int a, int b, int c = 0) {
    e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
}

void dfs(int u, int fa, int sum) {
    for (int i = h[u]; ~i; i = ne[i]) {
        int v = e[i];
        if (v == fa) continue;
        dfs(v, u, sum + w[i]);
    }
    ans = max(ans, sum);
}

int main() {
    memset(h, -1, sizeof h);
    cin >> n;
    for (int i = 1; i < n; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        add(a, b, c), add(b, a, c);
    }
    // 暴力换根
    for (int i = 1; i <= n; i++) {
        ans = 0;
        dfs(i, 0, 0);
        res = min(res, ans);
    }
    printf("%d\n", res);
    return 0;
}