c#学习笔记1-简单算法

  1 using System;
  2 namespace Demo
  3 {
  4     class Studycs
  5     {
  6         public static void Main(String[] args)
  7         {
  8             // String result = Revert("abcdef");
  9             int[] numbers = { 8, 2, 3, 4, 6 };
 10             //  int result = searchTree(numbers, 7);
 11 
 12             int[] result=sortSelect(numbers);
 13             foreach(int item in result)
 14             {
 15                 Console.WriteLine(item);
 16             }
 17             //  char c ='c';
 18             //  String result = toCompareChar("aABCDEFghiJKm");
 19            
 20             Console.ReadKey();
 21         }
 22 
 23         /// <summary>
 24         /// 翻转字符串
 25         /// </summary>
 26         /// <param name="str"></param>
 27         /// <returns></returns>
 28         static String Revert(String str)
 29         {
 30             String result = String.Empty;
 31             char[] array = str.ToCharArray();
 32             for(int i = array.Length - 1; i >= 0; i--)
 33             {
 34                 result += array[i];
 35             }
 36             return result;
 37         }
 38 
 39         /// <summary>
 40         /// 二分查找
 41         /// </summary>
 42         /// <param name="array"></param>
 43         /// <param name="number"></param>
 44         /// <returns></returns>
 45         static int  searchTree(int[] array,int number)
 46         {
 47             int min =0;
 48             int max = array.Length-1;
 49             int index =-1;
 50             while (max >= min)
 51             {
 52                 int result = (min + max) / 2;
 53                 if (array[result] == number)
 54                 {
 55                     index = result;
 56                     break;
 57                 }
 58                 else if (array[result] > number)
 59                 {
 60                     max = result - 1;
 61                 }
 62                 else
 63                 {
 64                     min = result + 1;
 65                 }
 66             }
 67             return index;
 68 
 69         }
 70 
 71         /// <summary>
 72         /// 一维数组最大值
 73         /// </summary>
 74         /// <param name="array"></param>
 75         /// <returns></returns>
 76         static int Max(int[] array)
 77         {
 78             int max =array[0];
 79             for(int i = 0; i < array.Length; i++)
 80             {
 81                 if (array[i] > max) max = array[i];
 82             }
 83             return max;
 84         }
 85 
 86         /// <summary>
 87         /// 查找数组的下标位置
 88         /// </summary>
 89         /// <param name="array"></param>
 90         /// <param name="n"></param>
 91         /// <returns></returns>
 92 
 93         static int path(int[] array,int n)
 94         {
 95             int result = -1;
 96             for(int i = 0; i < array.Length; i++)
 97             {
 98                 if (n == array[i]) result = i;
 99             }
100             return result;
101         }
102 
103         /// <summary>
104         /// 查找字符串的下表位置
105         /// </summary>
106         /// <param name="str"></param>
107         /// <param name="c"></param>
108         /// <returns></returns>
109 
110         static int  searchStr(String str ,char c)
111         {
112             int result = 0;
113             char[] array = str.ToCharArray();
114             for(int i = 0; i < array.Length; i++)
115             {
116                 if (c == array[i])
117                 {
118                     result++;
119                 }
120             }
121             return result;
122         }
123 
124         /// <summary>
125         /// 平均数
126         /// </summary>
127         /// <param name="array"></param>
128         /// <returns></returns>
129 
130         static Double avg(int[] array)
131         {
132             Double count=0;
133 
134             for(int i = 0; i < array.Length; i++)
135             {
136                 count += array[i];
137             }
138 
139             return count / array.Length;
140         }
141 
142         /// <summary>
143         /// 选择排序
144         /// </summary>
145         /// <param name="array"></param>
146         /// <returns></returns>
147         static int[] sortSelect(int[] array)
148         {
149             for(int i =0; i < array.Length - 1; i++)
150             {
151                 for(int j=i+1; j < array.Length; j++)
152                 {
153                     if (array[i] > array[j])
154                     {
155                         int temp = array[i];
156                         array[i] = array[j];
157                         array[j] = temp;
158                     }
159                 }
160             }
161             return array;
162         }
163 
164 
165         /// <summary>
166         /// 大小写字符转换
167         /// </summary>
168         /// <param name="str"></param>
169         /// <returns></returns>
170         static String toCompareChar(String str)
171         {
172             String result ="";
173             char[] array = str.ToCharArray();
174             for(int i=0; i < array.Length; i++)
175             {
176                 if(array[i]>='A' && array[i] <= 'Z')
177                 {
178                     result += Convert.ToChar(array[i] + 32);
179                 }
180                 if (array[i] >= 'a' && array[i] <= 'z')
181                 {
182                     result += Convert.ToChar(array[i] -32);
183                 }
184             }
185             return result;
186 
187         }
188     }
189 }