How to find all the permutation of the string by backtracking using C#?

Find the character in the first position and swap the rest of the character with the first character. Like in ABC, in the first iteration three strings are formed: ABC, BAC, and CBA by swapping A with A, B and C respectively. Repeat step for the rest of the characters like fixing second character B and so on. Now swap again to go back to the previous position. from ABC, we formed ABC by fixing B again, and we backtrack to the previous position and swap B with C. So, now we got ABC and ACB.

Example

 Live Demo

using System;
namespace ConsoleApplication{
   public class BackTracking{
      public void StringPermutation(string word, int start, int end){
         if (start == end){
            Console.WriteLine(word);
         }
         else{
            for (int i = start; i <= end; i++){
               Swap(ref word, start, i);
               StringPermutation(word, start + 1, end);
               Swap(ref word, start, i);
            }
         }
      }
      private void Swap(ref string word, int start, int end){
         char[] arr = word.ToCharArray();
         char temp = arr[start];
         arr[start] = arr[end];
         arr[end] = temp;
         word = new string(arr);
      }
   }
   class Program{
      static void Main(string[] args){
         BackTracking b = new BackTracking();
         b.StringPermutation("ABC", 0, 2);
      }
   }
}

Output

ABC
ACB
BAC
BCA
CBA
CAB