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

斐波拉契數列：

  1,1,2,3,5,8,13,21,34,55,89......

  n=1或n=2時，1

   n>2 時，An=A(n-1)+A(n-2);

 

兩種實現方法：

遞歸：這是面試官更想要的結果，盡管實現方式很多

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

 

While循環：使用python語音寫這個方法，代碼會少很多（使用   a,b = b,a+b 一句代碼代替了 數據換位操作）

#region 循環實現
        /// <summary>
        /// While循環
        /// </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("\n");
            return SeondNum;
        }
        #endregion

 

示例代碼：

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 斐波拉契數列
{

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("斐波拉契數列：\n  1,1,2,3,5,8,13,21,34,55,89,144......");
            //使用遞歸實現：
            Console.WriteLine("遞歸實現：");
            Console.WriteLine(string.Format("n=5,value={0}", Recursive(5)));
            Console.WriteLine(string.Format("n=10,value={0}", Recursive(10)));
            Console.WriteLine();
            //使用循環實現
            Console.WriteLine("while循環實現：");
            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 遞歸實現
        /// <summary>
        /// recursive 遞歸
        /// </summary>
        public static int Recursive(int position)
        {
            if (position == 1 || position == 2)
                return 1;
            else
                return Recursive(position - 1) + Recursive(position - 2);
        }
        #endregion

        #region 循環實現
        /// <summary>
        /// While循環
        /// </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("\n");
            return SeondNum;
        }
        #endregion

    }
}

 

運行效果：