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[];
 int x,y;
 int main()
 {
     while(~scanf("%d",&n))
     {
         memset(fa,,sizeof(fa));
         for(int i=;i<=n;i++)
         {
             scanf("%d%d",&x,&y);
             fa[x]=y;
         }
         int la=,lb=;
         int k=;
         while(fa[k]!=k)
         {
             la++;
             k=fa[k];
         }
         k=;
         while(fa[k]!=k)
         {
             lb++;
             k=fa[k];
         }
         if (la==lb) printf("You are my brother\n");
         else
         if (lb>la) printf("You are my younger\n");
         else
         if (lb<la) printf("You are my elder\n");
     }
     return ;
 }