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”

 

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 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