【ACM河南省赛第五四原题】Substring，acm河南省

【ACM河南省赛第五四原题】Substring，acm河南省

描述

You are given a string input. You are to find the longest substring of input such that the reversal of the substring is also a substring of input. In case of a tie, return the string that occurs earliest in input. 

Note well: The substring and its reversal may overlap partially or completely. The entire original string is itself a valid substring . The best we can do is find a one character substring, so we implement the tie-breaker rule of taking the earliest one first.

输入

The first line of input gives a single integer, 1 ≤ N ≤ 10, the number of test cases. Then follow, for each test case, a line containing between 1 and 50 characters, inclusive. Each character of input will be an uppercase letter ('A'-'Z').

输出

Output for each test case the longest substring of input such that the reversal of the substring is also a substring of input

样例输入

3                   
ABCABA
XYZ
XCVCX

样例输出

ABA
X
XCVCX

#include<iostream>
#include<string>
#include<algorithm>
#include<string.h>
using namespace std;
int main()
{
    int n,i,j,flag;
    string s1,ss;
    cin>>n;
    string s;
    while(n--)
    {
        cin>>s;
        flag=0;
        for(i=s.length(); i>0; i--)
        {
            for(j=0; j+i<=s.length(); j++)
            {

                ss=s.substr(j,i);             //从指定位置复制字符串
                s1=ss;
                reverse(s1.begin(),s1.end());//颠倒字符串
                if(s.find(s1)!=-1)
                {
                    cout<<ss<<endl;
                    flag=1;
                    break;
                }
            }
            if(flag==1)  break;
        }
    }

    return 0;
}