Listing all permutations of a string/integer

Question

A common task in programming interviews (not from my experience of interviews though) is to take a string or an integer and list every possible permutation.

Is there

Answer 1

Here is one more implementation of the algo mentioned.

public class Program
{
    public static void Main(string[] args)
    {
        string str = "abcefgh";
        var astr = new Permutation().GenerateFor(str);
        Console.WriteLine(astr.Length);
        foreach(var a in astr)
        {
            Console.WriteLine(a);
        }
        //a.ForEach(Console.WriteLine);
    }
}

class Permutation
{
    public string[] GenerateFor(string s)
    {  

        if(s.Length == 1)
        {

            return new []{s}; 
        }

        else if(s.Length == 2)
        {

            return new []{s[1].ToString()+s[0].ToString(),s[0].ToString()+s[1].ToString()};

        }

        var comb = new List();

        foreach(var c in s)
        {

            string cStr = c.ToString();

            var sToProcess = s.Replace(cStr,"");
            if (!string.IsNullOrEmpty(sToProcess) && sToProcess.Length>0)
            {
                var conCatStr = GenerateFor(sToProcess);



                foreach(var a in conCatStr)
                {
                    comb.Add(c.ToString()+a);
                }


            }
        }
        return comb.ToArray();

    }
}