剑指offer 09变态跳台阶

public class Solution {

    public  static void main(String[] args){
        long startTime=System.currentTimeMillis();
        System.out.println("第4项的结果是："+JumpFloorII(4));
        long endTime=System.currentTimeMillis();
        System.out.println("程序执行的时间："+(endTime-startTime)+"ms");
    }
    /*递归*/
    public static int JumpFloorII(int target){
        if(target==1){
            return 1;
        }else{
            return 2*JumpFloorII(target-1);
        }
    }
    /*左移*/
    /*public static int JumpFloorII(int target){
            int a=1;
            return a<<(target-1);
    }*/
    
}

function jumpFloorII(number)
{
    if(number==1){
        return number;
    }else{
          return 2*jumpFloorII(number-1);      
    }// write code here
}