题解 | #跳台阶#

//时间复杂度O(2^n) 空间复杂度:递归栈的空间
public class Solution {
     public int jumpFloor(int target) {
         if(target==1)
             return 1;
         else if(target==2)
             return 2;
         else
             return jumpFloor(target-1)+jumpFloor(target-2);
     }
  
 //时间复杂度O(n) 空间复杂度O(1)
     public int jumpFloor(int target) {
        int a = 1, b=1, c=1;
         for(int i=2;i<=target;i++){
             c = a+b;
             a = b;
             b = c;
         }
         return c;
    }
}