斐波拉契数列（1,1,2,3,5,8,13,21,34,55,89......）

斐波拉契数列：

1,1,2,3,5,8,13,21,34,55,89......

n=1或n=2时，1

n>2 时，An=A(n-1)+A(n-2);

两种实现方法：

递归：这是面试官更想要的结果，尽管实现方式很多

 1  #region 递归实现
 2         /// <summary>
 3         /// recursive 递归
 4         /// </summary>
 5         public static int Recursive(int position)
 6         {
 7             if (position == 1 || position == 2)
 8                 return 1;
 9             else
10                 return Recursive(position - 1) + Recursive(position - 2);
11         }
12         #endregion

递归

While循环：使用python语音写这个方法，代码会少很多（使用 a,b = b,a+b 一句代码代替了数据换位操作）

 1 #region 循环实现
 2         /// <summary>
 3         /// While循环
 4         /// </summary>
 5         /// <param name="position"></param>
 6         /// <returns></returns>
 7         public static int WhileMath(int position)
 8         {            
 9             int curr=1; //n
10             int firstNum = 0;//a
11             int SeondNum = 1;//b
12 
13             int tmp = 0;
14             while (curr < position)                
15             {
16                 Console.Write(string.Format("{0,5},",SeondNum));
17 
18                 tmp = firstNum;
19                 firstNum=SeondNum;
20                 SeondNum+=tmp;
21 
22                 curr++;
23             }
24             Console.Write(string.Format("{0,5},", SeondNum));
25 
26             Console.Write("
");
27             return SeondNum;
28         }
29         #endregion

while循环

示例代码：

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 
 6 /*
 7  * 1,1,2,3,5,8,13,21,34,55,89......
 8  * 
 9  * n>2:An=A(n-1) + A(n-2)
10  * */
11 namespace 斐波拉契数列
12 {
13 
14     class Program
15     {
16         static void Main(string[] args)
17         {
18             Console.WriteLine("斐波拉契数列：
  1,1,2,3,5,8,13,21,34,55,89,144......");
19             //使用递归实现：
20             Console.WriteLine("递归实现：");
21             Console.WriteLine(string.Format("n=5,value={0}", Recursive(5)));
22             Console.WriteLine(string.Format("n=10,value={0}", Recursive(10)));
23             Console.WriteLine();
24             //使用循环实现
25             Console.WriteLine("while循环实现：");
26             Console.WriteLine(string.Format("n=5,value={0}", WhileMath(5)));
27             Console.WriteLine(string.Format("n=10,value={0}", WhileMath(10)));
28             Console.WriteLine();
29 
30             Console.Read();
31 
32         }
33 
34         #region 递归实现
35         /// <summary>
36         /// recursive 递归
37         /// </summary>
38         public static int Recursive(int position)
39         {
40             if (position == 1 || position == 2)
41                 return 1;
42             else
43                 return Recursive(position - 1) + Recursive(position - 2);
44         }
45         #endregion
46 
47         #region 循环实现
48         /// <summary>
49         /// While循环
50         /// </summary>
51         /// <param name="position"></param>
52         /// <returns></returns>
53         public static int WhileMath(int position)
54         {            
55             int curr=1; //n
56             int firstNum = 0;//a
57             int SeondNum = 1;//b
58 
59             int tmp = 0;
60             while (curr < position)                
61             {
62                 Console.Write(string.Format("{0,5},",SeondNum));
63 
64                 tmp = firstNum;
65                 firstNum=SeondNum;
66                 SeondNum+=tmp;
67 
68                 curr++;
69             }
70             Console.Write(string.Format("{0,5},", SeondNum));
71 
72             Console.Write("
");
73             return SeondNum;
74         }
75         #endregion
76 
77     }
78 }

示例代码

运行效果：