题目链接 考察并查集，（最小生成树）题目很简单 用k记录树根的个数，k-1就是还需要建设的路 #include
    
     #include
     
      using namespace std;struct node{
        int x,y;}s[1005];int father[1005];int Find(int x){
        if(x==father[x]) return x;    father[x]=Find(father[x]);    return father[x];}void Union(int x,int y){
        x=Find(x);    y=Find(y);    if(x!=y)    {
            father[x]=y;    }}int main(void){
        int n,m,i,j,k,l;    while(scanf("%d",&n)==1&&n)    {
            scanf("%d",&m);        for(i=0;i