get permutations of a string

gistfile1.cs

  public static void Permute(string str)
    {
        int length = str.Length;
        bool[] used = new bool[length];
        StringBuilder output = new StringBuilder();
        doPermute(str, output, used, length, 0);
    }

    public static void doPermute(string input, StringBuilder output,
        bool[] used, int length, int level)
    {
        if (level == length)
        {
            Console.WriteLine(output.ToString());
            return;
        }

        for(int i=0; i< length;i++)
        {
            if (used[i])
                continue;

            output.Append(input[i]);
            used[i] = true;
            doPermute(input, output, used, length, level + 1);
            used[i] = false;

            output.Length = output.Length - 1;


        }
    }