String Permute

using System;
using System.Collections.Generic;
using System.Linq;

namespace StringPermute
{
    static class Program
    {
        static void Main()
        {
            var word = "abc";
            foreach (var s in Permuta(string.Empty, word.ToArray()).Distinct())
                Console.WriteLine(s);
        }

        private static IEnumerable<string> Permuta(string a, char[] b)
        {
            if (b.Length == 0)
                yield return a;
            for (var i = 0; i < b.Length; i++)
            {
                foreach (var s in Permuta(a + b[i], b.Where((c, j) => j != i).ToArray()))
                    yield return s;
            }
        }
    }
}