hdu 1213 (并查集)

#include<string.h>
#include<stdio.h>
#include<stdlib.h>
int pre[30005];
int Find(int x)
{
int r=x;
while(r!=pre[r])
r=pre[r];
int i=x,j;
while(pre[i]!=r)
{
j=pre[i];
pre[i]=r;
i=j;
}
return r;
}
void join(int x,int y)
{
int fx=Find(x),fy=Find(y);
if(fx!=fy)
{
pre[fx]=fy;
//printf("fx=%d,fy=%d\n",fx,fy);
}
}
int a[30003];
int t[3000];
int main()
{

int n,m,T;
scanf("%d",&T);
while(T--)
{
scanf("%d%d",&n,&m);
int i,x,y,num;
for(i=1;i<=n;i++)
pre[i]=i;
//printf("n=%d m=%d\n",n,m);
while(m--)
{
scanf("%d%d",&x,&y);
join(x,y);
}
memset(t,0,sizeof(t));
for(i=1;i<=n;i++)
t[Find(i)]=1;
int ans=0;
for(i=1;i<=n;i++)
if(t[i])
ans++;
printf("%d\n",ans);

}
}