一些常用算法 练手的的代码

看了平时写的一些东西 做的一些例子 让电脑按照你的意图去显示一些东西 你会发现 “原来编程真的很有意思的”

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 staticvoid 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 staticvoid 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 case1:
 40                         tmpChar ='①';
 41 break;
 42 case2:
 43                         tmpChar ='②';
 44 break;
 45 case3:
 46                         tmpChar ='③';
 47 break;
 48 case4:
 49                         tmpChar ='④';
 50 break;
 51 case5:
 52                         tmpChar ='⑤';
 53 break;
 54 case6:
 55                         tmpChar ='⑥';
 56 break;
 57 case7:
 58                         tmpChar ='⑦';
 59 break;
 60 case8:
 61                         tmpChar ='⑧';
 62 break;
 63 case9:
 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(newstring(str).Trim());
 78         }
 79 
 80 staticvoid 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 staticvoid 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 staticvoid 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 staticvoid 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