Question

C#

Palindrome Permutation: Given a string, write a function to check if it is a permutation of a palindrome. A palindrome is a word or phrase that is the same forwards and backwards. A permutation is a rearrangement of letters. The palindrome does not need to be limited to just dictionary words.

Input: Tact Coa

Output: True (permutations: "taco cat", "atco cta", etc.)

Comment your code to explain it.

Answer 1

// if you have any problem let em know i will try to help you. Thank you.

using System;

class MainClass {

  public static bool isPallindromePermutation(string str)
  {
    str=str.ToLower();  // convert the string to lowercase
    int[] arr;
    arr=new int[26]; // an array to store the count of each character
    int odd=0; // count number of odd numbers times any character occurs
   for(int i=0;i<26;i++){
      arr[i]=0;
   }
    for(int i=0;i<str.Length;i++)
    {
      if(str[i]!=' '){   // it is not space
      int k=(str[i]-'a');
      arr[k]=arr[k]+1;
      }
    }
    foreach(int a in arr)
    {
      if(a%2!=0)
         odd++;
    }
    if(odd<=1)  // if there is only one character or no character with odd number of times occur then it is possible 
       return true;
    else
    return false;

  }

  public static void Main (string[] args) {

    Console.WriteLine("Enter a string: ");
    string str=Console.ReadLine();
    Console.WriteLine (isPallindromePermutation(str));
  }
}

// Sample output:-