class Solution
{
    public int jumpFloor(int number)
    {
        // write code here
//         if(number==1)
//             return 1;
//         if(number==2)
//             return 2;
//         return jumpFloor(number-1)+jumpFloor(number-2);
           return jump(number, out  _);
    }
    
    public int jump(int number,out int before){
        if(number==1)
        {
            before=1;
            return 1;
        }
        
        var a=jump(number-1,out before);
        var ans=a+before;
        before=a;
        return ans;
    }
}最好采用线性递归的办法,这是从后向前递归的,淡然也可以从前向后递归