Networking POJ - 1287

#include<iostream>
#include<cstdio>
#include<queue>
#include<cstring>

using namespace std;

const int N = 1000+5;

struct Edge{
    int u, v, dist;

    Edge(){
        u = 0;
        v = 0;
        dist = 0;
    };

    Edge(int a, int b, int c){
        u = a;
        v = b;
        dist = c;
    }
}edge;

bool operator <(Edge a, Edge b)
{
    return a.dist > b.dist;
}

priority_queue<Edge> q;

int judge[N][N] = {0};
int pre[N*N/2] = {0};

void init()
{
//    memset(judge, 0, sizeof(judge));
    for(int i=0; i<N*N/2; i++){
        pre[i] = i;
    }
}

int Find(int a)
{
    return pre[a] == a ? a : pre[a] = Find(pre[a]);
}

void Union(int a, int b)
{
    a = Find(a), b = Find(b);

    if(a == b){
        return;
    }
    else{
        pre[a] = b;
        return;
    }
}

void Kruskal()
{
    int sum = 0;

    while(!q.empty()){
        edge = q.top();
        q.pop();

        if(Find(edge.u) != Find(edge.v)){
            sum += edge.dist;

            Union(edge.u, edge.v);
        }
    }

    cout << sum << endl;
}

int main() 
{
    int n, m;

    while(cin >> n >> m && n) {
        while (!q.empty()) {
            q.pop();
        }

        init();

        for (int i = 1; i <= m; i++) {
        	int u, v, l;
            cin >> u >> v >> l;
                //        judge[u][v] = 1;
                //           judge[v][u] = 1;
            q.push(Edge(u, v, l));
        }

        Kruskal();
    }

    return 0;

}