全排列

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

namespace test
{
    class Program
    {
        static void Main(string[] args)
        {
            char[] c = { 'A', 'B', 'C', 'D' };
            quanpailie<char> q = new quanpailie<char>();
            q.perm(c, 0, 3);

        }
    }
    public class quanpailie<T>
    {
        public void swap(ref T X,  ref T Y)
        {
            T tmp;
            tmp = X;
            X = Y;
            Y = tmp;
        }
        public void perm(T[] list, int k, int m)
        {
            int i;
            if (k > m)
            {
                for (i = 0; i <= m; i++)
                    Console.Write(list[i]);
                Console.Write("/n");
            }
            else
            {
                for (i = k; i <= m; i++)
                {
                    swap(ref list[k], ref list[i]);
                    perm(list, k + 1, m);
                    swap(ref list[k], ref list[i]);
                }
            }
        }
    }
}