c# .Net 常见算法

using System.Collections.Generic;
using System.ComponentModel.Design;
using System.Linq;

namespace TestDelay
{
    internal class Program
    {
        static void Main()
        {
            int[] arry = new int[] { 12, 32, 434, 56, 2, 1, 9, 0 };
            BubbleSort(arry);
            Console.WriteLine("冒泡排序：" + string.Join(",", arry));

            Demo1(7);
            Reverse("I am a good man");

            Demo2(4);

            Demo3(30);
        }
        /// <summary>
        /// 冒泡排序
        /// </summary>
        /// <param name="arry"></param>
        public static void BubbleSort(int[] arry)
        {
            for (int i = 0; i < arry.Length - 1; i++)
            {
                for (int j = i + 1; j < arry.Length; j++)
                {
                    if (arry[i] > arry[j])
                    {
                        var temp = arry[i];
                        arry[i] = arry[j];
                        arry[j] = temp;
                    }
                }
            }
        }

        /// 求以下表达式的值，写出您想到的一种或几种实现方法： 1-2+3-4+……+m
        /// 拆分为(1-2)+(3-4)+(5-6)+...+m
        /// </summary>
        /// <param name="m"></param>
        public static void Demo1(int m)
        {
            #region 第一种方式
            int result1 = 0;
            if (m % 2 == 0)
                result1 = -(m / 2);
            else
                result1 = -(m - 1) / 2 + m;
            #endregion
            #region 第二种方式
            int result2 = 0;
            for (int i = 1; i <= m; i++)
            {
                if (i % 2 == 0)
                    result2 = result2 - i;
                else
                    result2 = result2 + i;
            }
            #endregion
            Console.WriteLine(result1 == result2);
        }

        /// <summary>
        /// 有一个字符串 "I am a good man",设计一个函数,返回 "man good a am I"。
        /// </summary>
        /// <param name="str"></param>
        public static void Reverse(string str)
        {
            var strArry = str.Split(" ");
            var result1 = string.Join(" ", strArry.Reverse());
            List<string> list = new List<string>();
            for (int i = strArry.Length - 1; i >= 0; i--)
            {
                list.Add(strArry[i]);
            }
            var result2 = string.Join(" ", list);
            Console.WriteLine(result1 == result2);
        }

        /// <summary>
        /// 有1、2、3、4个数字,能组成多少个互不相同且无重复数字的三位数?都是多少?
        /// </summary>
        /// <param name="number"></param>
        public static void Demo2(int number)
        {
            List<string> list = new List<string>();
            for (int b = 1; b <= number; b++)
            {
                for (int s = 1; s <= number; s++)
                {
                    if (b != s)
                    {
                        for (int g = 1; g <= number; g++)
                        {
                            if (b != s && b != g && s != g)
                                list.Add($"{b}{s}{g}");
                        }
                    }
                }
            }
            Console.WriteLine($"1-{number},共有：{list.Count}个不重复三位数，分别是：{string.Join(",", list)}");
        }


        /// <summary>
        /// 1、1、2、3、5、8、13、21、34，....⽤C#递归写出算法，算出第30个数。
        /// </summary>
        /// <param name="number"></param>
        public static void Demo3(int number)
        {
            List<int> list= new List<int>();
            Recursion(0, list);
            var result = string.Join(" ", list);
        }
        /// <summary>
        /// 1、1、2、3、5、8、13、21、34，....⽤C#递归写出算法，算出第30个数
        /// </summary>
        /// <param name="number"></param>
        /// <param name="list"></param>
        public static void Recursion(int number, List<int> list)
        {
            if (number <= 1)
                list.Add(1);
            else
                list.Add(list[list.Count - 2] + list[list.Count - 1]);
            if (number < 30)
                Recursion(number + 1, list);
        }
    }









}