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Make palindromic string non-palindromic by rearranging its letters
• Difficulty Level : Medium
• Last Updated : 01 Feb, 2019

Given a string str containing lowercase alphabets (a – z). The task is to print the string after rearranging some characters such that the string becomes non-palindromic. If its impossible to make the string non-palindrome then print -1.

Examples:

Input: str = “abba”
Output: aabb

Input: str = “zzz”
Output: -1

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: If all the characters in the string are same then no matter how you rearrange the characters, string will remain the same and will be palindromic. Now, if a non-palindromic arrangement exists, the best way to rearrange the characters is to sort the string which will form continuous segment of same characters and will never be palindromic. In order to reduce the time required to sort the string, we can store the frequencies of all the 26 characters and print them in sorted manner.

Below is the implementation of the above approach:

## C++

 `// CPP Program to rearrange letters of string``// to find a non-palindromic string if it exists``#include ``using` `namespace` `std;`` ` `// Function to print the non-palindromic string``// if it exists, otherwise prints -1``void` `findNonPalinString(string s)``{``    ``int` `freq[26] = { 0 }, flag = 0;`` ` `    ``for` `(``int` `i = 0; i < s.size(); i++) {`` ` `        ``// If all characters are not``        ``// same, set flag to 1``        ``if` `(s[i] != s[0])``            ``flag = 1;`` ` `        ``// Update frequency of the current character``        ``freq[s[i] - ``'a'``]++;``    ``}`` ` `    ``// If all characters are same``    ``if` `(!flag)``        ``cout << ``"-1"``;``    ``else` `{`` ` `        ``// Print characters in sorted manner``        ``for` `(``int` `i = 0; i < 26; i++)``            ``for` `(``int` `j = 0; j < freq[i]; j++)``                ``cout << ``char``(``'a'` `+ i);``    ``}``}`` ` `// Driver Code``int` `main()``{``    ``string s = ``"abba"``;`` ` `    ``findNonPalinString(s);`` ` `    ``return` `0;``}`

## Java

 `// Java Program to rearrange letters of string ``// to find a non-palindromic string if it exists ``class` `GfG ``{ `` ` `// Function to print the non-palindromic string ``// if it exists, otherwise prints -1 ``static` `void` `findNonPalinString(``char` `s[]) ``{ ``    ``int` `freq[] = ``new` `int``[``26``];``    ``int` `flag = ``0``; `` ` `    ``for` `(``int` `i = ``0``; i < s.length; i++) ``    ``{ `` ` `        ``// If all characters are not ``        ``// same, set flag to 1 ``        ``if` `(s[i] != s[``0``]) ``            ``flag = ``1``; `` ` `        ``// Update frequency of ``        ``// the current character ``        ``freq[s[i] - ``'a'``]++; ``    ``} `` ` `    ``// If all characters are same ``    ``if` `(flag == ``0``) ``        ``System.out.println(``"-1"``); ``    ``else` `    ``{ `` ` `        ``// Print characters in sorted manner ``        ``for` `(``int` `i = ``0``; i < ``26``; i++) ``            ``for` `(``int` `j = ``0``; j < freq[i]; j++) ``                ``System.out.print((``char``)(``'a'` `+ i)); ``    ``} ``} `` ` `// Driver Code ``public` `static` `void` `main(String[] args) ``{ ``    ``String s = ``"abba"``; ``     ` `    ``findNonPalinString(s.toCharArray()); ``}``} `` ` `// This code is contributed by ``// Prerna Saini.`

## Python3

 `# Python3 Program to rearrange letters of string ``# to find a non-palindromic string if it exists `` ` `# Function to print the non-palindromic string ``# if it exists, otherwise prints -1 ``def` `findNonPalinString(s): `` ` `    ``freq ``=` `[``0``] ``*` `(``26``) ``    ``flag ``=` `0`` ` `    ``for` `i ``in` `range``(``0``, ``len``(s)): `` ` `        ``# If all characters are not same,``        ``# set flag to 1 ``        ``if` `s[i] !``=` `s[``0``]:``            ``flag ``=` `1`` ` `        ``# Update frequency of the current ``        ``# character ``        ``freq[``ord``(s[i]) ``-` `ord``(``'a'``)] ``+``=` `1`` ` `    ``# If all characters are same ``    ``if` `not` `flag:``        ``print``(``"-1"``) ``     ` `    ``else``:``         ` `        ``# Print characters in sorted manner ``        ``for` `i ``in` `range``(``0``, ``26``): ``            ``for` `j ``in` `range``(``0``, freq[i]): ``                ``print``(``chr``(``ord``(``'a'``) ``+` `i),``                               ``end ``=` `"") `` ` `# Driver Code ``if` `__name__ ``=``=` `"__main__"``:`` ` `    ``s ``=` `"abba"``    ``findNonPalinString(s) `` ` `# This code is contributed by``# Rituraj Jain`

## C#

 `// C# Program to rearrange letters ``// of string to find a non-palindromic``// string if it exists ``using` `System;`` ` `class` `GfG ``{ `` ` `    ``// Function to print the ``    ``// non-palindromic string ``    ``// if it exists, otherwise ``    ``// prints -1 ``    ``static` `void` `findNonPalinString(``char` `[]s) ``    ``{ ``        ``int` `[]freq = ``new` `int``[26]; ``        ``int` `flag = 0; ``     ` `        ``for` `(``int` `i = 0; i < s.Length; i++) ``        ``{ ``     ` `            ``// If all characters are not ``            ``// same, set flag to 1 ``            ``if` `(s[i] != s[0]) ``                ``flag = 1; ``     ` `            ``// Update frequency of ``            ``// the current character ``            ``freq[s[i] - ``'a'``]++; ``        ``} ``     ` `        ``// If all characters are same ``        ``if` `(flag == 0) ``            ``Console.WriteLine(``"-1"``); ``        ``else``        ``{ ``     ` `            ``// Print characters in sorted manner ``            ``for` `(``int` `i = 0; i < 26; i++) ``                ``for` `(``int` `j = 0; j < freq[i]; j++) ``                        ``Console.Write((``char``)(``'a'` `+ i)); ``        ``} ``    ``} ``     ` `    ``// Driver Code ``    ``public` `static` `void` `Main() ``    ``{ ``        ``string` `s = ``"abba"``; ``         ` `        ``findNonPalinString(s.ToCharArray()); ``    ``} ``} `` ` `// This code is contributed by Ryuga`
Output:
```aabb
```

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