using System;

public class Program

{

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

    {

        if (a == b) return;

​

        a ^= b;

        b ^= a;

        a ^= b;

    }

​

    public static void GetPer(char[] list)

    {

        int x = list.Length - 1;

        GetPer(list, 0, x);

    }

​

    private static void GetPer(char[] list, int k, int m)

    {

        if (k == m)

        {

            Console.WriteLine(list);

        }

        else

            for (int i = k; i <= m; i++)

            {

                   Swap(ref list[k], ref list[i]);

                   GetPer(list, k + 1, m);

                   Swap(ref list[k], ref list[i]);

            }

    }

​

    public static void Main()

    {

        string str = "abc";

        char[] arr = str.ToCharArray();

        GetPer(arr);

    }

​

}