urumuqi H skiing DP

#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <cstring>
#include <iterator>
#include <cmath>
#include <algorithm>
#include <stack>
#include <deque>
#include <map>
#include <set>
#include <queue>
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define mem0(a) memset(a,0,sizeof(a))
#define mem1(a) memset(a,-1,sizeof(a))
#define sca(x) scanf("%d",&x)
#define de printf("=======\n")
typedef long long ll;
using namespace std;
const ll t = 1e8;

const int maxn = 1e4+100;
map<pair<int, int>, int> p;
int d[maxn]; // d[i] 表示i号节点为起点的最长距离为d[i]
int isend[maxn];
int n, m;

int dfs( int index ) {
    if( isend[index] ) return 0;
    for( int i = 1; i <= n; i++ ) {
        if( i != index ) {
            int dis = p[make_pair(index, i)];
            if( dis ) {
                d[index] = max( d[index], dis + dfs(i) );
            }
        }
    }
    return d[index];
}
int main() {
    int t;
    sca(t);
    while( t-- ) {
        scanf( "%d%d", &n, &m );
        p.clear();
        mem0(d);
        mem0(isend);
        for( int i = 1; i <= m; i++ ) {
            int s, e, l;
            scanf( "%d%d%d", &s, &e, &l );
            p.insert(make_pair(make_pair(s, e), l));
            isend[s] = 0;
            isend[e] = 1;
        }
        int ans = 0;
        for( int i = 1; i <= n; i++ ) {
            ans = max( ans, dfs(i) );
        }
        printf( "%d\n", ans );
    }
    return 0;
}