DoubleString | Topcoder Archive

Problem Statement

A string is called a square if it can be created by concatenating two copies of the same string. For example, "CANCAN" is a square because it consists of two copies of the string "CAN". Other squares include "AA", "ZZZZ", and "BERIBERI". The strings "AAAAA" and "HAHAHA" are not squares.

You are given a String S. Return "square" (quotes for clarity) if there is a string T such that S = T + T. Otherwise, return "not square". Note that the return value is case-sensitive.

Definition

Class:: DoubleString
Method:: check
Parameters:: String
Returns:: String
Method signature:: String check(String S)
(be sure your method is public)

Constraints

The length of S will be between 1 and 50, inclusive.
Each character in S will be an uppercase letter ('A'-'Z').

Examples

```
"MAZAIMAZAI"
```
```
Returns: "square"
```
If T is "MAZAI", T+T will be "MAZAIMAZAI".
```
"MAMAZAIZAI"
```
```
Returns: "not square"
```
In this case, there is no string T for which T+T will be S.
```
"IOI"
```
```
Returns: "not square"
```
The length of S is odd, so it's impossible to make S by concatenating the same string twice.
```
"AA"
```
```
Returns: "square"
```
T will be "A".
```
"ABCCBA"
```
```
Returns: "not square"
```
```
"Y"
```
```
Returns: "not square"
```

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