You are my brother

问题 : You are my brother

时间限制: 1 Sec  内存限制: 128 MB

题目描述

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.

输入

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.

输出

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.

样例输入

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

样例输出

You are my elder
You are my brother

解题思路

根据所给的数对，判断1，2分别组成的链的长短。

#include <stdio.h>
#include <string.h>
int main()
{
    int n, a, b;
    int s[2010];
    while (~scanf("%d", &n))
    {
        memset(s, 0, sizeof(s));
        for (int i = 0; i < n; i++)
        {
            scanf("%d%d", &a, &b);
            s[a] = b;
        }
        a = 1;
        b = 2;
        while (s[a] && s[b])
        {
            a = s[a];
            b = s[b];
        }
        if (!s[a] && s[b])
            puts("You are my younger");
        else if (!s[a] && !s[b])
            puts("You are my brother");
        else puts("You are my elder");
    }
    return 0;
}