LCA最近公共祖先(POJ1330)

#include <iostream>
#include <stdio.h>
#include <string.h>
using namespace std;

const int maxn = 10005;

bool vis[maxn];
int father[maxn];

int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        memset(father,-1,sizeof(father));
        memset(vis,0,sizeof(vis));

        int n;
        scanf("%d",&n);
        int a,b;
        for(int i=0;i<n-1;i++)
        {
            scanf("%d%d",&a,&b);
            father[b]=a;
        }

        scanf("%d%d",&a,&b);
        while(b!=-1)
        {
            vis[b]=true;
            b=father[b];
        }

        while(!vis[a])
            a=father[a];
        printf("%d\n",a);

    }
    return 0;
}