C# 排列组合取值 控制台程序

  
using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

 

 

    class Program

    {

        static void Main(string[] args)

        {

            //List<string> list = new List<string>();

            //for (int i = 0; i < 6; i++)

            //{

            //    list.Add(i.ToString());

            //}

            List<string> list = new List<string> { "0", "1", "2", "5", "8", "4", "12", "32" }; 

            Combination.C(list, 3);

            Console.WriteLine("---------------------");

            //Console.Read();

            Combination.A(list, 0, 3);

            Console.WriteLine("---------------------");

            Console.Read();

        }

    }

 

   public abstract class Combination

    {

        public static List<string> GetCombination(List<string> SampleList, int m)

        {

            if (m == 1)

            {

                return SampleList;

            }

            List<string> result = new List<string>();

            if (SampleList.Count == m)

            {

                StringBuilder temp_sb = new StringBuilder();

                foreach (string s in SampleList)

                {

                    temp_sb.Append(s);

                }

                result.Add(temp_sb.ToString());

                Console.WriteLine(temp_sb.ToString());

                return result;

            }

            string temp_firstelement = SampleList[0];

            SampleList.RemoveAt(0);

            List<string> temp_samplist1 = new List<string>();

            temp_samplist1.AddRange(SampleList);

            List<string> temp_list1 = GetCombination(temp_samplist1, m - 1);

            foreach (string s in temp_list1)

            {

                result.Add(temp_firstelement + s);

                Console.WriteLine(temp_firstelement + s);

            }       

            List<string> temp_samplist2 = new List<string>();

            temp_samplist2.AddRange(SampleList);

            List<string> temp_list2 = GetCombination(temp_samplist2, m);

            result.AddRange(temp_list2);           

            return result;

        }

        /// <summary>

        /// 对数组进行组合操作，选取selectCount个元素进行组合

        /// </summary>

        /// <param name="lsArray">即将进行组合操作的数组</param>

        /// <param name="selectCount">选取的元素的个数</param>

        public static void C(List<string> lsArray, int selectCount)

        {

            int totolcount = lsArray.Count;

            int[] currectselect = new int[selectCount];

            int last = selectCount - 1;

            for (int i = 0; i < selectCount; i++)

            {

                currectselect[i] = i;

            }

            while (true)

            {

                for (int i = 0; i < selectCount; i++)

                {

                    Console.Write(" {0} ", lsArray[currectselect[i]]);

                }

                Console.WriteLine();

                if (currectselect[last] < totolcount - 1)

                {

                    currectselect[last]++;

                }

                else

                {

                    int pos = last;

                    while (pos > 0 && currectselect[pos - 1] == currectselect[pos] - 1)

                    {

                        pos--;

                    }

                    if (pos == 0) return;

                    currectselect[pos - 1]++;

                    for (int i = pos; i < selectCount; i++)

                    {

                        currectselect[i] = currectselect[i - 1] + 1;

                    }

                }

            }

        }

        /// <summary>

        /// 对数组进行全排列

        /// </summary>

        /// <param name="lsArray">要进行全排列的数组</param>

        /// <param name="begin">进行全排列的开始下标</param>

        /// <param name="end">进行全排列的结束下标</param>

       public static void A(List<string> lsArray, int begin, int end)

        {

            if (begin == end)

            {

                for (int i = 0; i <= end; i++)

                   Console.Write(" {0} ", lsArray[i]);

                Console.WriteLine();

            }

            for (int i = begin; i <= end; i++)

            {

                Swap(lsArray, begin, i);

                A(lsArray, begin + 1, end);

                Swap(lsArray, begin, i);

            }

        }

 

        /// <summary>

        /// 交换数组中的下标为x,y的值

        /// </summary>

        /// <param name="lsArray">该数组</param>

        /// <param name="x"></param>

        /// <param name="y"></param>

        static void Swap(List<string> lsArray, int x, int y)

        {

            string t = lsArray[x];

            lsArray[x] = lsArray[y];

            lsArray[y] = t;

        }

    }