[并查集]LA 3644 X-Plosives

#include <cstdio>
#include <cstring>

const int INF=0x3f3f3f3f;
const int MAXN=1e5+10;

int parent[MAXN];
int findset(int a){
	return parent[a]!=a ? parent[a] = find(parent[a]) :a ;
}
int main()
{
	int a,b,ans=0,x,y;
	while(scanf("%d",&a)==1 ){
		for(int i=0;i<MAXN;++i)parent[i]=i;
		ans=0;
		while(a!=-1){
			scanf("%d",&b);
			x=findset(a);y=findset(b);
			if(x==y)ans++;
			else parent[y]=x;
			scanf("%d",&a);
		}
		printf("%d\n", ans);
	}	
	return 0;
}