POJ 1611 The Suspects (并查集)

题意: 求解与0有关系的所有人  ->并查集求解

Code:

#include<iostream>
#include<cstdio>
#include<cstring>

using namespace std;
const int maxn = 30005;
int fa[maxn], n, m;
void init(){
	for(int i=0; i<=n; i++){
		fa[i]=i;
	}
	return ;
}
int find(int a){
	if(fa[a]==a)return a;
	fa[a]=find(fa[a]);
	return fa[a];
}
void Union(int a, int b){
	int f1 = find(a);
	int f2 = find(b);
	if(f1!=f2){
		fa[f1]=f2;
	}
	return ;
}
int main()
{
	//freopen("in.txt", "r", stdin);
	while(~scanf("%d %d", &n, &m), n||m){
		init();
		int i, j, k;
		int x, y;
		while(m--){
			scanf("%d", &k);
			scanf("%d", &y);
			for(i=2; i<=k; i++){
				scanf("%d", &x);
				Union(x, y);
				y = x;
			}
		}
		int ans=1;
		int p = find(0);//0的那组的编号
		for(i=1; i<=n; i++){ 
			if(fa[i]==i && fa[i]!=p) continue;
			if(find(i)==p) {//和0同组
				ans++;
			}
		}
		printf("%d\n", ans);
	}
	return 0;
}