一些常用算法 练手的的代码

  1 using System;
  2  using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Text;
  5 using System.Data;
  6 using System.Data.SqlClient;
  7 using System.IO;
  8 
  9 namespace studyDemo
 10 {
 11     class Program
 12     {
 13         static void Main(string[] args)
 14         {
 15            
 16             //recursion(1, 0);
 17             //sortDemo();
 18             //commonMultiple(13, 4);
 19 
 20             //getDir(new DirectoryInfo(@"c:\"),0);
 21             //numToString(757657578);
 22 
 23             //string str = "hello world!!";
 24             //foreach (char c in str)
 25             //    Console.WriteLine(c);
 26         }
 27 
 28         static void numToString(int num)//把整型转换成字符串
 29         {
 30             char[] str = { ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ' };
 31             int indx = 0;
 32             
 33             while (num > 0)
 34             {
 35                 int tmpNum = num % 10;
 36                 char tmpChar;
 37                 switch (tmpNum)
 38                 {
 39                     case 1:
 40                         tmpChar = '①';
 41                         break;
 42                     case 2:
 43                         tmpChar = '②';
 44                         break;
 45                     case 3:
 46                         tmpChar = '③';
 47                         break;
 48                     case 4:
 49                         tmpChar = '④';
 50                         break;
 51                     case 5:
 52                         tmpChar = '⑤';
 53                         break;
 54                     case 6:
 55                         tmpChar = '⑥';
 56                         break;
 57                     case 7:
 58                         tmpChar = '⑦';
 59                         break;
 60                     case 8:
 61                         tmpChar = '⑧';
 62                         break;
 63                     case 9:
 64                         tmpChar = '⑨';
 65                         break;
 66                     default:
 67                         tmpChar = '〇';
 68                         break;
 69                 }
 70                 if (indx < str.Length)
 71                     str[str.Length - indx - 1] = tmpChar;
 72                 indx++;
 73 
 74                 num /= 10;
 75             }
 76            
 77             Console.WriteLine(new string(str).Trim());
 78         }
 79 
 80         static void commonMultiple(int num1, int num2)//求最小公倍数 的算法
 81         {
 82             int comNum = 0;
 83             int tmp = -1;
 84             if (num1 > num2)
 85             {
 86                 tmp = num1;
 87                 num1 = num2;
 88                 num2 = tmp;
 89             }
 90 
 91             for (int i = num2; i <= num1 * num2; i++)
 92             {
 93                 if (i % num1 == 0 && i % num2 == 0)
 94                 {
 95                     comNum = i;
 96                     break;
 97                 }
 98             }
 99             if (tmp == -1)
100                 Console.WriteLine("{0}跟{1}的最小公倍数是：{2}", num1, num2, comNum);
101             else
102                 Console.WriteLine("{0}跟{1}的最小公倍数是：{2}",num2 ,num1 , comNum);
103         }
104 
105         static void sortDemo()//排序算法
106         {
107             int[] arr = { 4, 5, 3, 678, 12, 78, 90, 1 };
108 
109             for (int i = 0; i < arr.Length; i++)
110             {
111                 for (int j = 0; j < arr.Length - 1; j++)
112                 {
113                     if (arr[j + 1] > arr[j])
114                     {
115                         int tmp;
116                         tmp = arr[j];
117                         arr[j] = arr[j + 1];
118                         arr[j + 1] = tmp;
119                     }
120                 }
121             }
122 
123             foreach (int n in arr)
124             {
125                 Console.WriteLine(n);
126             }
127         }
128 
129         static void getDir(DirectoryInfo dir, int level)//递归算法 遍历目录
130         {
131             foreach (DirectoryInfo d in dir.GetDirectories())
132             {
133                 for (int i = 0; i < level; i++)
134                     Console.Write(" ");
135                 Console.WriteLine(d.Name);
136                 getDir(d, level + 1);
137             }
138         }
139 
140         static void recursion(int node, int level)//递归算法 树状图
141         {
142             //数据库里表的结构：
143             /*
144              * create table tree
145              * (
146              * id int primary key identity (1,1) ,
147              * nm varchar(20),
148              * pId int 
149              * ) 
150              * id主键自增列 nm名称 pId父ID（从属于）
151              */
152             string sql = "select * from tree where pid=@1";
153             SqlConnection conn = new SqlConnection(@"server=.\sqlexpress;database=tempdb;Integrated Security=true");
154             conn.Open();
155 
156             SqlCommand cmd = new SqlCommand(sql, conn);
157             cmd.Parameters.Add(new SqlParameter("@1", node));
158 
159             SqlDataReader dr = cmd.ExecuteReader();
160 
161             while (dr.Read())
162             {
163                 for (int i = 0; i <= level; i++)
164                     Console.Write("---");
165                 Console.WriteLine(dr["nm"]);
166                 int id = dr.GetInt32(0);
167 
168                 SqlConnection conn2 = new SqlConnection(@"server=.\sqlexpress;database=tempdb;Integrated Security=true");
169                 conn2.Open();
170                 SqlCommand cmd2 = new SqlCommand("select count(*) from tree where pid=@1", conn2);
171                 cmd2.Parameters.Add(new SqlParameter("@1", id));
172                 object hasChild = cmd2.ExecuteScalar();
173                 if (Convert.ToInt32(hasChild) != 0)
174                     recursion(id, level + 1);
175 
176                 conn2.Close();
177             }
178 
179             dr.Close();
180             conn.Close();
181         }
182     }
183 }
184