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