using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Fibonacci {     class Program     {         static void Main(string[] args)         {             Console.WriteLine("Would you like to know which Fibonacci Numbers：");             int number = Convert.ToInt32(Console.ReadLine());             //             Function obj = new Function();             Console.WriteLine();             Console.Write("The {0} Fibonacci number is：{1}", number, obj.Fibonacci(number));             //             Console.WriteLine();             Function obj2 = new Function(number);             Console.Write("The {0} Fibonacci number is：{1}", number, obj2.BottomUpNotRecursion(number));             //             Console.WriteLine();             Console.Write("The {0} Fibonacci number is：{1}", number, obj2.TopDownRecursion(number));             Console.ReadKey();         }     } }

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Fibonacci {     class Function     {         private int[] array;         public Function()         {         }         /// <summary>         /// Function         /// </summary>         /// <param name="length"></param>         public Function(int length)         {             if (length > 0)             {                 array = new int[length + 1];                 array[0] = 1;                 array[1] = 1;             }             if (length == 0)             {                 array = new int[1];                 array[0] = 1;             }         }         /// <summary>         /// Fibonacci数列定义为：         ///             无穷数列1，1，2，3，5，8，13，21，34，55，……         ///        ┌ 1             n=0             ///   F(n)=│ 1             n=1         ///        └ F(n-1)+F(n-2) n>1         /// </summary>         /// <param name="number">第几个斐波那契数</param>         /// <returns></returns>         public int Fibonacci(int number)         {             if (number <= 1)             {                 return 1;             }             else             {                 return Fibonacci(number - 1) + Fibonacci(number - 2);             }         }         /// <summary>         /// 动态规划思想：         ///     1.自底向上非递归算法         /// </summary>         /// <param name="number"></param>         /// <returns></returns>         public int BottomUpNotRecursion(int number)         {             int copynumber = 0;             if (number < 2)             {                 copynumber = 1;             }             else             {                 int one = array[0];                 int two = array[1];                 for (int i = 2; i < array.Length; i++)                 {                     array[i] = one + two;                     one = two;                     two = array[i];                     copynumber = array[i];                 }             }             return copynumber;         }         /// <summary>         ///     2.自顶向下递归算法         /// </summary>         /// <param name="number"></param>         /// <returns></returns>         public int TopDownRecursion(int number)         {             if (number <= 2)             {                 if (number == 0)                     return array[0];                 if (number == 1)                     return array[1];                 if (number == 2)                     return array[2] = array[0] + array[1];             }             else             {                 //递归只是一个“牵引线”，目的是为了让数组储存值。                 TopDownRecursion(number - 1);                 array[number] = array[number - 1] + array[number - 2];             }             return array[number];         }     } }