bzoj3296: [USACO2011 Open] Learning Languages

shui

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
using namespace std;
int fa[11000];
int findfa(int x)
{
    if(fa[x]==x)return x;
    fa[x]=findfa(fa[x]);return fa[x];
}
void unit(int x,int y)
{
    int fx=findfa(x),fy=findfa(y);
    if(fx!=fy)fa[fx]=fy;
}
int last[31000];
bool v[11000];
int main()
{
    int n,m;
    scanf("%d%d",&n,&m);
    memset(last,0,sizeof(last));
    for(int i=1;i<=n;i++)fa[i]=i;
    for(int i=1;i<=n;i++)
    {
        int T,c;
        scanf("%d",&T);
        for(int j=1;j<=T;j++)
        {
            scanf("%d",&c);
            if(last[c]!=0)unit(i,last[c]);
            last[c]=i;
        }
    }
    int ans=0;
    memset(v,false,sizeof(v));
    for(int i=1;i<=n;i++)
    {
        int FA=findfa(i);
        if(v[FA]==false)
            v[FA]=true, ans++;
    }
    printf("%d\n",ans-1);
    return 0;
}