UVA - Wormholes

#include<bits/stdc++.h>
using namespace std;
#define fast()(ios_base::sync_with_stdio(false),cin.tie(NULL));

struct connect
{
    int u;
    int v;
    int w;
}eg[2020];
int main()
{
    fast();
    int t;
    cin>>t;
    while(t--)
    {
        int node,edge;
        cin>>node>>edge;
        for(int i=0;i<edge;i++)cin>>eg[i].u>>eg[i].v>>eg[i].w;
        int distance[1005];
        for(int i=1;i<=node;i++)distance[i]=INT_MAX;
        distance[0]=0;
        for(int i=0;i<node-1;i++)
        {
            for(int j=0;j<edge;j++)
            {
                if(distance[eg[j].u]+eg[j].w<distance[eg[j].v])
                    distance[eg[j].v]=distance[eg[j].u]+eg[j].w;
            }
        }
        bool flag=false;
        for(int i=0;i<edge;i++)
        {
            if(distance[eg[i].u]+eg[i].w<distance[eg[i].v])flag=true;
        }
        if(flag)cout<<"possible"<<endl;
        else cout<<"not possible"<<endl;
    }
    return 0;
}