继续畅通工程

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int MAX = 5000;
int p[MAX];
struct edge{
    int s;
    int e;
    int w;
    int i;
}a[MAX];
bool cmp(edge i,edge j){
    return i.w <j.w;
}
int find(int x){
return x == p[x] ? x:p[x] = find(p[x]);
}
int main()
{
    int T;
    while(~scanf("%d",&T)&&T){
            int sum = 0;
            for(int i = 1; i <= T;i++)
            scanf("%d%d%d%d",&a[i].s,&a[i].e,&a[i].w,&a[i].i);
            for(int i = 1; i <= T;i++)
                p[i] = i;
            for(int i = 1; i <= T;i++)
                if(a[i].i == 1)
                 a[i] .w = 0;
            sort(a+1,a+T+1,cmp);

           for(int i = 1; i <=T;i++){
                int fx = find(a[i].s),fy = find(a[i].e);
              if(fx != fy){
                p[fx] = fy;
                sum += a[i].w;
              }
           }
           printf("%d\n",sum);
    }
    return 0;
}