NBUT 1218 You are my brother

$dfs$。

记录一下每一个节点的深度就可以了。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
using namespace std;

int n;
int dep[3000],in[3000];
vector<int>g[3000];

void dfs(int x,int y)
{
    dep[x]=y;
    for(int i=0;i<g[x].size();i++)
        dfs(g[x][i],y+1);
}

int main()
{
    while(~scanf("%d",&n))
    {
        for(int i=0;i<=2000;i++) g[i].clear();
        memset(in,0,sizeof in);

        for(int i=1;i<=n;i++)
        {
            int A,B; scanf("%d%d",&A,&B);
            g[B].push_back(A);
            in[A]++;
        }

        for(int i=1;i<=2000;i++)
        {
            if(in[i]==0)
            {
                dfs(i,1);
            }
        }

        if(dep[1]==dep[2]) printf("You are my brother
");
        else if(dep[1]>dep[2]) printf("You are my elder
");
        else printf("You are my younger
");

    }

    return 0;
}