Bellman ford

vector < vector <pii> > graph(2005);
int vis[2005];


void bellmanford(int n, int s){
    for(int i=0;i<n;i++) vis[i] = 99999999999999;
    vis[s] = 0;
    for(int i=1;i<n;i++){
        for(int j=0;j<n;j++){
            for(int k=0;k<graph[j].size();k++){
                vis[graph[j][k].first] = min(vis[graph[j][k].first], vis[j]+graph[j][k].second);
            }
        }
    }
    for(int j=0;j<n;j++){
        for(int k=0;k<graph[j].size();k++){
            if(vis[j]+graph[j][k].second<vis[graph[j][k].first]){
                cout << "possible" <<endl;
                return;
            }
        }
    }
    cout << "not possible" <<endl;
}