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

 #region 递归实现
        /// <summary>
        /// recursive 递归
        /// </summary>
        public static int Recursive(int position)
        {
            if (position == 1 || position == 2)
                return 1;
            else
                return Recursive(position - 1) + Recursive(position - 2);
        }
        #endregion

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）

#region 循环实现
        /// <summary>
        /// While循环
        /// </summary>
        /// <param name="position"></param>
        /// <returns></returns>
        public static int WhileMath(int position)
        {            
            int curr=1; //n
            int firstNum = 0;//a
            int SeondNum = 1;//b

            int tmp = 0;
            while (curr < position)                
            {
                Console.Write(string.Format("{0,5},",SeondNum));

                tmp = firstNum;
                firstNum=SeondNum;
                SeondNum+=tmp;

                curr++;
            }
            Console.Write(string.Format("{0,5},", SeondNum));

            Console.Write("
");
            return SeondNum;
        }
        #endregion

示例代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

/*
 * 1,1,2,3,5,8,13,21,34,55,89......
 * 
 * n>2:An=A(n-1) + A(n-2)
 * */
namespace 斐波拉契数列
{

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("斐波拉契数列：
  1,1,2,3,5,8,13,21,34,55,89,144......");
            //使用递归实现：
            Console.WriteLine("递归实现：");
            Console.WriteLine(string.Format("n=5,value={0}", Recursive(5)));
            Console.WriteLine(string.Format("n=10,value={0}", Recursive(10)));
            Console.WriteLine();
            //使用循环实现
            Console.WriteLine("while循环实现：");
            Console.WriteLine(string.Format("n=5,value={0}", WhileMath(5)));
            Console.WriteLine(string.Format("n=10,value={0}", WhileMath(10)));
            Console.WriteLine();

            Console.Read();

        }

        #region 递归实现
        /// <summary>
        /// recursive 递归
        /// </summary>
        public static int Recursive(int position)
        {
            if (position == 1 || position == 2)
                return 1;
            else
                return Recursive(position - 1) + Recursive(position - 2);
        }
        #endregion

        #region 循环实现
        /// <summary>
        /// While循环
        /// </summary>
        /// <param name="position"></param>
        /// <returns></returns>
        public static int WhileMath(int position)
        {            
            int curr=1; //n
            int firstNum = 0;//a
            int SeondNum = 1;//b

            int tmp = 0;
            while (curr < position)                
            {
                Console.Write(string.Format("{0,5},",SeondNum));

                tmp = firstNum;
                firstNum=SeondNum;
                SeondNum+=tmp;

                curr++;
            }
            Console.Write(string.Format("{0,5},", SeondNum));

            Console.Write("
");
            return SeondNum;
        }
        #endregion

    }
}

运行效果：