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问题 : You are my brother

时间限制: 1 Sec 内存限制: 128 MB

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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

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;
}