C++ :

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 2e5 + 10;
vector<pair<int, ll> > e[maxn];
ll dp[maxn]; //
ll ans[maxn];
int n;
 
void dfs1(int u, int fa) //
{
    ll tmp = 0;
    for(auto x : e[u])
    {
        int v = x.first;
        if(v == fa) continue;
        //dp[v] = x.second;
        if(e[v].size() == 1) //
            dp[v] = e[v][0].second;
        dfs1(v, u);
        dp[u] += min(dp[v], x.second);
    }
}
 
void dfs(int u, int fa) //
{
    ll tmp = 0; //
    for(auto x : e[u])
    {
        if(e[u].size() == 1)
            tmp = x.second;
        else
        {
            int v = x.first;
            tmp += min(dp[v], x.second);
        }
    }
    for(auto x : e[u]) //
    {
        int v = x.first; //
        if(v == fa) continue;
        ll rt = dp[u], son = dp[v];
        dp[u] = tmp; //
        if(e[u].size() > 1) //
           dp[u] = dp[u] - min(dp[v], x.second);
        dp[v] = 0;
        for(auto m : e[v]) //
        {
            dp[v] += min(dp[m.first], m.second);
        }
        ans[v] = dp[v]; //
        dfs(v, u);
        //dp[u] = rt, dp[v] = son; //
    }
}
 
int main()
{

    int t;
    scanf("%d", &t);
    while(t--)
    {
        scanf("%d", &n);
        for(int i = 0; i <= n; ++i)
            e[i].clear(), dp[i] = 0;
        for(int i = 1; i < n; ++i)
        {
            int u, v, w;
            scanf("%d%d%d", &u, &v, &w);
            e[u].push_back(make_pair(v, w));
            e[v].push_back(make_pair(u, w));
        }
        dfs1(1, 0);
        ans[1] = dp[1];
        dfs(1, 0);
  
        ll res = -1e9;
        for(int i = 1; i <= n; ++i)
            res = max(res, ans[i]);
        printf("%lld\n", res);
    }
    return 0;
}