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河南省第四届程序设计大赛--Substring

 
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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

很一般的一道题,类似回文字串。但不同的是回文子串的意思是正着看和倒着看是相同的。比如ABCDBA的最长回文字串是A,但这道题的意思是,the reversal of the substring is also a substring of input。就是它的逆子串也存在在这个字符串中,如上例,结果应该是AB。这点很关键,读题一点要仔细,要不然就会想当然。就这么一点错误,可能你再检查N次也不知道哪里错了。

思路很简单:

1.


代码如下:



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