并查集 POJ 1330

#include <iostream>#include<stdio.h>#include<string.h>using namespace std;const int maxn = 10010;int t,n;int x,y;int father[maxn],bj[maxn];void bl(int n){    while(n !=father[n])    {        bj[n] = 1;        n = father[n];    }    bj[n] = 1;    return;}int sh(int m){    while(bj[m] != 1)    {        m = father[m];    }    return m;}int main(){    scanf("%d",&t);    while(t--)    {        scanf("%d",&n);        for(int i=1;i<=n;i++)        {            father[i] = i;        }        for(int i=1;i<=n-1;i++)        {            int a,b;            scanf("%d%d",&a,&b);            father[b] = a;        }        memset(bj,0,sizeof(bj));        scanf("%d%d",&x,&y);        bl(x);        int ans = sh(y);        printf("%d\n",ans);    }    return 0;}