HDU1879最小生成树 通畅工程

#include<stdio.h>#include<string.h>#include<algorithm>using namespace std;struct Road{    int c1,c2,cost,done;}road[5051];int father[110];int cmp(const Road a,const Road b){    return a.cost<b.cost;}int find(int x){    if(father[x]==-1)    return x;    return father[x]=find(father[x]);}int merge(int a,int b){    int x=find(a);    int y=find(b);    if(x==y)return 0;    if(x>y)father[x]=y;    else father[y]=x;    return 1;}int main(){    int n,m,count,sum,i;    while(scanf("%d",&n)&&n){        sum=0;        count=0;        memset(father,-1,sizeof(father));        m=n*(n-1)/2;        for(i=1;i<=m;i++){        scanf("%d%d%d%d",&road[i].c1,&road[i].c2,&road[i].cost,&road[i].done);        if(road[i].done&&merge(road[i].c1,road[i].c2))        count++;        }        sort(road+1,road+m+1,cmp);        for(i=1;i<=m;i++){            if(merge(road[i].c1,road[i].c2)&&road[i].done==0){                count++;                sum+=road[i].cost;            }            if(count==n-1)            break;        }        printf("%d\n",sum);    }    return 0;}