Capital

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

const int N = 100010;
using pii = pair<int, int>;

vector<pii> G[N];
int mx = 0;

void dfs(int u, int p, int d) { // u = current node, p = parent, d = current distance
    // don't need to check visited because graph is a tree, there's only one way to go back (through parent)
    mx = max(mx, d);
    for (auto v : G[u]) {
        if (v.first != p) // don't go back to parent
            dfs(v.first, u, d+v.second); // go from u to v, so distance += weight of edge (u,v)
    }
}

int main()
{
    int n;
    scanf("%d", &n);
    for (int i = 0; i < n-1; ++i) {
        int u, v, w;
        scanf("%d%d%d", &u, &v, &w);
        G[u].push_back({v, w});
        G[v].push_back({u, w});
    }
    dfs(1, 0, 0);
    printf("%d\n", mx);

    return 0;
}