NBUT 1218 You are my brother 2010辽宁省赛

Time limit 1000 ms

Memory limit 131072 kB

Little A gets to know a new friend, Little B, recently. One day, they realize that they are family 500 years ago. Now, Little A wants to know whether Little B is his elder, younger or brother.

 

Input

There are multiple test cases.
For each test case, the first line has a single integer, n (n<=1000). The next n lines have two integers a and b (1<=a,b<=2000) each, indicating b is the father of a. One person has exactly one father, of course. Little A is numbered 1 and Little B is numbered 2.
Proceed to the end of file.

Output

For each test case, if Little B is Little A’s younger, print “You are my younger”. Otherwise, if Little B is Little A’s elder, print “You are my elder”. Otherwise, print “You are my brother”. The output for each test case occupied exactly one line.

Sample Input

5
1 3
2 4
3 5
4 6
5 6
6
1 3
2 4
3 5
4 6
5 7
6 7

Sample Output

You are my elder
You are my brother


签到题，树的基本概念，代码如下：

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stack>
#include<map>
#include<set>
#include<queue>
#include<cmath>
#include<string>
using namespace std;
int n,t;
int fa[2005];
int x,y;
int main()
{
    while(~scanf("%d",&n))
    {
        memset(fa,0,sizeof(fa));
        for(int i=1;i<=n;i++)
        {
            scanf("%d%d",&x,&y);
            fa[x]=y;
        }
        int la=0,lb=0;
        int k=1;
        while(fa[k]!=k)
        {
            la++;
            k=fa[k];
        }
        k=2;
        while(fa[k]!=k)
        {
            lb++;
            k=fa[k];
        }
        if (la==lb) printf("You are my brother
");
        else
        if (lb>la) printf("You are my younger
");
        else
        if (lb<la) printf("You are my elder
");
    }
    return 0;
}