hdoj1232畅通工程

#include<cstdio>#include<cstring>#include<iostream>using namespace std;const int N = 1000;int father[N],rank[N],ans[N];void make_set(int n){    for(int i=1;i<=n;i++){        father[i] = i;        rank[i] = 0;    }}int find(int x){    return x==father[x]?x:find(father[x]);}void Union(int x,int y){     x = find(x);y = find(y);     if(x==y)return;     if(rank[x]<rank[y])father[x]=y;     else{         if(rank[x]==rank[y])rank[x]++;         father[y] = x;     }}int main(){    int n, m, i, sum,a ,b;    while(scanf("%d",&n),n){        sum = 0;        scanf("%d",&m);        memset(ans,0,sizeof(ans));        make_set(n);        for(i=1;i<=m;i++){            scanf("%d%d",&a,&b);            Union(a,b);        }        for(i=1;i<=n;i++){            if(i==father[i])sum++;        }              printf("%d\n",sum-1);    }    return 0;}