输入两个整数 n 和 m，从数列1，2，3.......n 中 随意取几个数,使其和等于 m ,要求将其中所有的可能组合列出来.

2010年中兴面试题编程

求解：输入两个整数 n 和 m，从数列1，2，3.......n 中 随意取几个数,使其和等于 m ,要求将其中所有的可能组合列出来.

 

using System;

using System.Collections.Generic;

 

namespace ConsoleApp

{

    class RunClass

    {

        static void Main()

        {

            new RunClass().Print(100, 13);

 

            Console.ReadLine();

        }

 

        public void Print(int n, int m, List<int> list = null)

        {

            if (n < 1 || m < 1)

            {

                return;

            }

 

            for (int i = 1; i <= n; i++)

            {

                if (i < m)

                {

                    List<int> childList = new List<int>();

                  

                    if (list != null)

                    {

                        childList.AddRange(list);

                    }

                    childList.Add(i);

 

                    Print(i - 1, m - i, childList);

                }

                else if (i == m)

                {

                    if (list != null)

                    {

                        foreach (int j in list)

                        {

                            Console.Write("{0} + ", j);

                        }

 

                        Console.WriteLine("{0}", m);

                    }

                }

            }

        }

    }

}