斐波那契数列的运算时间

斐波那契数列，F0=0，F1=1，Fn=F(n-1)+F(n-2)（n>=2，n∈N*）

Fibonacci Sequence Calculator

硬件： I3 Cpu + 8G Ram

1.用C#递归计算：

        static void Main(string[] args)
        {
            int n = 40;
            Stopwatch watch = new Stopwatch();
            watch.Start();
            int num = RecursionFibonacci(n);
            watch.Stop();
            Console.WriteLine("n="+n);
            Console.WriteLine("num=" + num);
            Console.WriteLine("time=" + watch.ElapsedMilliseconds+"ms");
        }
        static int RecursionFibonacci(int n)
        {
            if (n < 1)
                return 0;
            if (n == 1)
                return 1;
            return RecursionFibonacci(n - 1) + RecursionFibonacci(n - 2);
        }

 

2.用java递归计算：

package com.example.fibonacci;

/**
 * Created by Administrator on 3/22/2014.
 */
public class Fibonacci {
    public static void main(String[] args){
        int n=40;
        long startTime=System.currentTimeMillis();
        int num=RecursionFibonacci(n);
        long endTime=System.currentTimeMillis();
        System.out.println("n="+n);
        System.out.println("num="+num);
        System.out.println("time="+(endTime-startTime)+"ms");
    }
    public static int RecursionFibonacci(int n){
        if(n<1)
            return 0;
        if(n==1)
            return 1;
        return RecursionFibonacci(n-1)+RecursionFibonacci(n-2);
    }
}

c#怎么就用了2238ms呢，落后的原因是什么？

3.用javascript递归计算：

<div>
    Fibonacci
    <input type="text" id="txtNum" value="40"/>
    <input type='button' id='btnFibonacci' value='Recursion' onclick="Do()" />
</div>
<script type="text/javascript">
    function RecursionFibonacci(n) {
        if (n < 1) {
            return 0;
        }
        if (n == 1) {
            return 1;
        }
        var num = RecursionFibonacci(n - 1) + RecursionFibonacci(n - 2);
        return num;
    }
    function Do () {
        var n = document.getElementById("txtNum").value;
        var beginDate = new Date();
        var num = RecursionFibonacci(n);
        var time = new Date() - beginDate;
        alert("n=" + n + "; num=" + num + "; time=" +time+"ms");
    }
</script>