HDU-1232-畅通工程（并查集）

题目链接
http://acm.hdu.edu.cn/showproblem.php?pid=1232
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<iostream>
#include<cstdio>
using namespace std;
struct node
{
    int x,y;
}s[];

int father[];

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)==&&n)
    {
        scanf("%d",&m);
        for(i=;i<m;i++)
        scanf("%d%d",&s[i].x,&s[i].y);
        for(i=;i<=n;i++)
        father[i]=i;
        for(i=;i<m;i++)
        {
            Union(s[i].x,s[i].y);
        }
        k=;
        for(i=;i<=n;i++)
        {
            if(i==father[i])
            k++;
        }
        printf("%d\n",k-);
    }
    return;
}