Kruskal

int Kruskal(int n) {
    sort(edge,edge+n*(n-1)/2);
    int sum=0;
    for(int i=0; i<n*(n-1)/2; i++) {
        if(Find(edge[i].f)!=Find(edge[i].t)) {
            Union(edge[i].f,edge[i].t);
            sum+=edge[i].c;
        }
    }
    return sum;
}