4731: 【GESP2509六级】货物运输

#include <algorithm>
#include <cstdio>
#include <vector>
using namespace std;
const int N = 1e5 + 5;
int n;
vector < vector < pair < int, int >>> e;
long long s, mx;
void dfs(int u, int f, long long d) {
    mx = max(d, mx);
    for (auto p: e) {
        if (p.first != f) {
            dfs(p.first, u, d + p.second);
        }
    }
}
int main() {
    scanf("%d", & n);
    e.resize(n + 1);
    for (int i = 1; i < n; i++) {
        int u, v, w;
        scanf("%d%d%d", & u, & v, & w);
        e.emplace_back(make_pair(v, w));
        e[v].emplace_back(make_pair(u, w));
        s += w;
    }
    dfs(1, 0, 0);
    printf("%lld\n", s * 2 - mx);
    return 0;
}