minimum spaning tree prim's

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <functional>
#include <queue>
#include <utility>
#include <list>
#include <climits>
#include <map>
#define P printf("\n");



using namespace std;
typedef pair<int, int> PAIR;

const  int INF = INT_MAX;


int main(int argc, char **argv) {


    int n, e, u,v, w;int spaningW=0;

    list<PAIR>:: iterator it;

    priority_queue<PAIR, vector<PAIR>, greater<PAIR>>q;

    //cout<<"code is sexy";
    cin>> n >> e;

    //cout<<"code is sexy"<<n<<" "<<e;

    bool visited[100];
    int dist[100];


    for(int i=0; i<=n; i++){
        dist[i] = 9999; visited[i]=false;

    }

    list<PAIR>graph[n+1];


       for (int i = 1; i <= e; i++) {

            cin >> u >> v >> w;

            graph[u].push_back(make_pair(w, v));
            graph[v].push_back(make_pair(w, u));

        }

    //cout<<"end";


        q.push(make_pair(0,1));



        while(!q.empty()){


            w = q.top().first;

            u = q.top().second;

            q.pop();

            if(visited[u])
                continue;

            visited[u]= true;

            spaningW +=w;

            for(it = graph[u].begin(); it != graph[u].end(); it++){


                    if(it->first< dist[it->second]){

                        q.push(make_pair(it->first, it->second));

                        dist[it->second] = it->first;

                        }

                }



            }


    P;
    cout<<spaningW;



    /*
     * 6 9
     * 1 2 3
     * 1 4 1
     * 2 3 3
     * 2 4 3
     * 3 4 1
     * 4 5 6
     * 3 5 5
     * 3 6 4
     * 5 6 2
     *
     *
     *
     *
     *
     * */


return 0;
}