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# Check if a string can be rearranged to form special palindrome

• Difficulty Level : Easy
• Last Updated : 21 May, 2021

Given a string str, the task is to check if it can be rearranged to get a special palindromic string. If we can make it print YES else print NO.
A string is called special Palindrome that contains an uppercase and a lower case character of the same character in the palindrome position. Example- ABCcba is a special palindrome but ABCCBA is not a special palindrome.
Examples:

```Input: str = "ABCcba"
Output: YES

Input: str = "ABCCBA"
Output: NO```

Approach: Check if the occurrence of the uppercase letter of a character is same as the occurrence of lower case letter of the same character. And also there should be only one odd occurring character. We increase the frequency of each uppercase character by 1 and decrease the frequency of each lower case character by 1. After this, there should be either zero, 1 or -1 in the frequency array If anything else occurs then we directly say NO else print YES.
Below is the implementation of the above approach:

## C++

 `// C++ implementation of the above approach``#include``using` `namespace` `std;` `// Driver code``int` `main()``{``    ``string s = ``"ABCdcba"` `;``        ` `    ``// creating a array which stores the``    ``// frequency of each character``    ``int` `u = {0};``    ``int` `n = s.length() ;``        ` `    ``for``(``int` `i = 0; i < n ; i++)``    ``{``        ``// Checking if a character is uppercase or not``        ``if``(``isupper``(s[i]))``        ``{``            ``// Increasing by 1 if uppercase``            ``u[s[i] - 65] += 1;``        ``}``        ``else``        ``{``            ``// Decreasing by 1 if lower case``            ``u[s[i] - 97] -= 1 ;``        ``}``            ` `    ``}``    ``bool` `f1 = ``true` `;``    ` `    ``// Storing the sum of positive``    ``// numbers in the frequency array``    ``int` `po = 0 ;``        ` `    ``// Storing the sum of negative``    ``// numbers in the frequency array``    ``int` `ne = 0 ;``        ` `    ``for` `(``int` `i = 0 ; i < 26 ; i++)``    ``{``        ``if` `(u[i] > 0)``            ``po += u[i] ;``            ` `        ``if` `(u[i] < 0)``            ``ne += u[i] ;``    ``}``    ` `    ``// If all character balances out then its Yes``    ``if` `(po == 0 && ne == 0)``        ``cout << (``"YES"``) << endl;``    ` `    ``// If there is only 1 character which``    ``// does not balances then also it is Yes``    ``else` `if` `(po == 1 && ne == 0)``        ``cout << (``"YES"``) << endl;``        ` `    ``else` `if` `(po == 0 && ne == -1)``        ``cout << (``"YES"``) << endl;``        ` `    ``else``        ``cout << (``"NO"``) << endl;``        ` `}` `// This code is contributed by``// Surendra_Gangwar`

## Java

 `// Java implementation of the above approach``public` `class` `Improve {`  `    ``public` `static` `void` `main(String args[])``    ``{``        ``String s = ``"ABCdcba"` `;``        ` `        ``// creating a array which stores the ``        ``// frequency of each character``        ``int` `u[] = ``new` `int``[``26``];``        ``int` `n = s.length() ;``        ` `        ``for``(``int` `i = ``0``; i < n ; i++)``        ``{``            ``// Checking if a character is uppercase or not``            ``if``(Character.isUpperCase(s.charAt(i)))``            ``{``                ``// Increasing by 1 if uppercase``                ``u[s.charAt(i) - ``65``] += ``1` `;``            ``}``            ``else``            ``{``                ``// Decreasing by 1 if lower case``                ``u[s.charAt(i) - ``97``] -= ``1` `;``            ``}``            ` `        ``}``        ``boolean` `f1 = ``true` `;``        ` `        ``// Storing the sum of positive ``        ``// numbers in the frequency array``        ``int` `po = ``0` `;``        ` `        ``// Storing the sum of negative ``        ``// numbers in the frequency array``        ``int` `ne = ``0` `;``        ` `        ``for` `(``int` `i = ``0` `; i < ``26` `; i++)``        ``{``            ``if` `(u[i] > ``0``)``                ``po += u[i] ;``            ` `            ``if` `(u[i] < ``0``)``                ``ne += u[i] ;``        ``}``        ` `        ``// If all character balances out then its Yes``        ``if` `(po == ``0` `&& ne == ``0``)``            ``System.out.println(``"YES"``) ;``        ` `        ``// If there is only 1 character which ``        ``// does not balances then also it is Yes``        ``else` `if` `(po == ``1` `&& ne == ``0``)``            ``System.out.println(``"YES"``) ;``        ` `        ``else` `if` `(po == ``0` `&& ne == -``1``)``            ``System.out.println(``"YES"``) ;``        ` `        ``else``            ``System.out.println(``"NO"``) ;``        ` `        ` `    ``}``    ``// This code is contributed by ANKITRAI1``}`

## Python3

 `# Python implementation of the above approach``s ``=` `"ABCdcba"` `# creating a list which stores the``# frequency of each character``u ``=` `[``0``] ``*` `26` `n ``=` `len``(s)``for` `i ``in` `range``(n):``    ``# Checking if a character is uppercase or not``    ``if` `(s[i].isupper()): ``        ``# Increasing by 1 if uppercase``        ``u[``ord``(s[i]) ``-` `65``] ``+``=` `1` `    ``else``:``        ``# Decreasing by 1 if lower case``        ``u[``ord``(s[i]) ``-` `97``] ``-``=` `1` `fl ``=` `True` `# Storing the sum of positive``# numbers in the frequency array``po ``=` `0`  `# Storing the sum of negative``# numbers in the frequency array``ne ``=` `0` `for` `i ``in` `range``(``26``):``    ``if` `(u[i] > ``0``):``        ``po ``+``=` `u[i]``    ``if` `(u[i] < ``0``):``        ``ne ``+``=` `u[i]` `# If all character balances out then its Yes``if` `(po ``=``=` `0` `and` `ne ``=``=` `0``): ``    ``print``(``"YES"``)` `# If there is only 1 character which``# does not balances then also it is Yes``elif` `(po ``=``=` `1` `and` `ne ``=``=` `0``): ``    ``print``(``"YES"``)``elif` `(po ``=``=` `0` `and` `ne ``=``=` `-``1``):``    ``print``(``"YES"``)``else``:``    ``print``(``"NO"``)`

## C#

 `// C# implementation of the``// above approach``using` `System;` `class` `GFG``{``public` `static` `void` `Main()``{``    ``string` `s = ``"ABCdcba"` `;``    ` `    ``// creating a array which stores``    ``// the frequency of each character``    ``int``[] u = ``new` `int``;``    ``int` `n = s.Length ;``    ` `    ``for``(``int` `i = 0; i < n ; i++)``    ``{``        ``// Checking if a character is``        ``// uppercase or not``        ``if``(Char.IsUpper(s[i]))``        ``{``            ``// Increasing by 1 if uppercase``            ``u[s[i] - 65] += 1 ;``        ``}``        ``else``        ``{``            ``// Decreasing by 1 if lower case``            ``u[s[i] - 97] -= 1 ;``        ``}``    ``}` `    ``// Storing the sum of positive``    ``// numbers in the frequency array``    ``int` `po = 0 ;``    ` `    ``// Storing the sum of negative``    ``// numbers in the frequency array``    ``int` `ne = 0 ;``    ` `    ``for` `(``int` `i = 0 ; i < 26 ; i++)``    ``{``        ``if` `(u[i] > 0)``            ``po += u[i] ;``        ` `        ``if` `(u[i] < 0)``            ``ne += u[i] ;``    ``}``    ` `    ``// If all character balances``    ``// out then its Yes``    ``if` `(po == 0 && ne == 0)``        ``Console.Write(``"YES"``+``"\n"``) ;``    ` `    ``// If there is only 1 character which``    ``// does not balances then also it is Yes``    ``else` `if` `(po == 1 && ne == 0)``        ``Console.Write(``"YES"``+``"\n"``) ;``    ` `    ``else` `if` `(po == 0 && ne == -1)``        ``Console.Write(``"YES"` `+ ``"\n"``) ;``    ` `    ``else``        ``Console.Write(``"NO"` `+ ``"\n"``) ;``}``}` `// This code is contributed``// by ChitraNayal`

## Javascript

 ``
Output:
`YES`

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