nyoj308-Substring

#include<stdio.h>
#include<string.h>
#include<string>
#include<math.h>
#include<stdlib.h>
#include<algorithm>
#include<iostream>
using namespace std;
int main()
{
    int t,i,j;
    scanf("%d",&t);
    while(t--)
    {
        string s1,s2,s3;
        cin>>s1;
        s2=s1;
        int ma=0;
        int  len=s1.size();
        reverse(s2.begin(),s2.end());
        for(i=0; i<len; i++)
        {
            for(j=1; j<=len-i; j++)
            {
                string::size_type pos=s2.find(s1.substr(i,j));
                if(pos!=string::npos&&ma<j)
                {
                    ma=j;
                    s3=s1.substr(i,j);
                }
            }

        }
        cout<<s3<<endl;
    }

}