HDU 1243 畅通project 并査集

Total Submission(s): 31033    Accepted Submission(s): 16313

4 2
1 3
4 3
3 3
1 2
1 3
2 3
5 2
1 2
3 5
999 0
0

1
0
2
998

Hint
Hint

水题，就是把有关系的联系在一起，不解释

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define N 10005

int father[N];

int cha(int x)
{
    if(x!=father[x])
        father[x]=cha(father[x]);
    return father[x];
}

int main()
{
    int i,n,m;
    while(scanf("%d",&n),n)
    {
        scanf("%d",&m);

        for(i=1;i<=n;i++)
            father[i]=i;

        int x,y;

        while(m--)
        {
            scanf("%d%d",&x,&y);
            int xx=cha(x);
            int yy=cha(y);
            father[xx]=yy;
        }


        int ans=-1;
        for(i=1;i<=n;i++)
            if(father[i]==i)
            ans++;

        printf("%d\n",ans);
    }
    return 0;
}