昨天把递归算法给看了看，java小实现了一下，用递归和循环实现费氏数列，针对其效率进行比较，测试用N=50，发现递归要把机子算爆才出结果。代码如下

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import java.util.*;
public class SimpleFib{
??? public static void main(String[] args)throws Exception{
??? ??? long [] fib=new long[100];
??? ??? int N;
??? ??? Scanner in=new Scanner(System.in);
??? ??? System.out.println("Input the N:/n");
??? ??? N=in.nextInt();
??? ??? fib[0]=1;
??? ??? fib[1]=1;
??? ??? for(int i=2;i<N;i++){
??? ??? ??? fib[i]=fib[i-1]+fib[i-2];
??? ??? }
??? ???
??? ??? System.out.println("the fib[N] is "+fib[N-1]);
??? }
}

??? /*通过递归实现?
??? public static void main(String[] args)throws Exception{
??? ??? int N;
??? ??? long sum;
??? ??? Scanner in=new Scanner(System.in);
??? ??? System.out.println("Input the N:/n");
??? ??? N=in.nextInt();
??? ??? SimpleFib Fib=new SimpleFib();
??? ??? sum=Fib.fib(N);
??? ??? System.out.println("The fib[N] is: "+sum);
??? }
???
??? public long fib(int n){
??? ??? if(n<=2)
??? ??? ??? return 1;
??? ??? else
??? ??? ??? return fib(n-1)+fib(n-2);
??? }
??? */

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不知道java中是否有可以计算测试用时间的函数，想测试一下算出结果的时耗。