using System;

​

// From http://stackoverflow.com/a/756083/1132522

public class Program

{

    public static void Main()

    {

        string str = "abc";

        char[] arr = str.ToCharArray();

        Permute(arr, 0, arr.Length - 1);

    }

    private static void Swap(ref char a, ref char b)

    {

        char tmp = a;

        a = b;

        b = tmp;

    }

​

    // SwapUsingBitWise could be used instead of Swap as in the original solution.

    private static void SwapUsingBitWise(ref char a, ref char b)

    {

        if (a == b)

            return;

        a ^= b;

        b ^= a;

        a ^= b;

    }

​

    private static void Permute(char[] elements, int recursionDepth, int maxDepth)

    {

        if (recursionDepth == maxDepth)

        {

            Console.WriteLine(elements);

            return;

        }

​

        for (int i = recursionDepth; i <= maxDepth; i++)

        {

            Swap(ref elements[recursionDepth], ref elements[i]);

            Permute(elements, recursionDepth + 1, maxDepth);

            // backtrack

            Swap(ref elements[recursionDepth], ref elements[i]);

        }

    }

}