hdu 1232

并查集 入门题

#include<cstdio>
#include<memory.h>
int par[1000];
int Find(int x)
{
    while(par[x] > 0)
        x = par[x];
    return x;
}
void Merge(int x,int y)
{
    int a,b;
    int tmp;
    a = Find(x);
    b = Find(y);
    if(a != b)
    {
        tmp = par[a] + par[b];
        if(par[a] < par[b]) //a 结点数多于 b的
        {
            par[b] = a;
            par[a] = tmp;
        }
        else
        {
            par[a] = b;
            par[b] = tmp;
        }
    }
}
int main()
{
    freopen("input.txt","r",stdin);
    int x,y,n,m;
    int cnt;
    while(scanf("%d",&n) && n)
    {
        cnt = -1;
        scanf("%d",&m);
        memset(par,-1,sizeof(par));
        while(m--)
        {
            scanf("%d%d",&x,&y);
            Merge(x,y);
        }
        for(int i = 1; i <= n; i++)
        {
            if(par[i] <= -1) cnt++;
        }
        printf("%d
",cnt);
    }
}