学步园

链接：http://acm.hdu.edu.cn/showproblem.php?pid=2545

并查集解决.

AC code:

#include <iostream>
#include <stdio.h>
using namespace std;
#define  Max 100001
int father[Max];
void Init()
{
	int i;
	for(i=0;i<Max;++i)
		father[i]=i;
}

int Findfather(int x)
{
	int count=0;
	while (x!=father[x])
	{
		count++;
		x=father[x];
	}
	return count;
}

void Union(int x,int y)
{
	father[y]=x;
}
int main()
{
	int n,m,x,y,i,t1,t2;
	while (scanf("%d%d",&n,&m),n&&m)
	{
		Init();
		for(i=0;i<n-1;++i)
		{
			scanf("%d%d",&x,&y);
			Union(x,y);
		}
		for(i=0;i<m;++i)
		{
			scanf("%d%d",&x,&y);
			t1=Findfather(x);
			t2=Findfather(y);
			if(t1<=t2)
			printf("lxh\n");
			else
			{
			printf("pfz\n");
			}
		}
	}
}