原文题目:
You are climbing a stair case. It takes n steps to reach to the top.
Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
Note: Given n will be a positive integer.
读题:
这个题目一看就知道是斐波那契数列的变形,因此有两种方法解决:递归和非递归,这里都给出,由于使用递归时的处理时间太长,提交系统后超时,因此提交采用非递归。
非递归方法:
class Solution(object): def climbStairs(self, n): """ :type n: int :rtype: int """ if n < 0: return 0 if n == 1 or n ==0: return 1 result = 1 pre = 1 while n >= 2: n -= 1 nextvalue = pre pre = result result = pre + nextvalue return result
递归方法:
class Solution(object): def climbStairs(self, n): """ :type n: int :rtype: int """ if n < 0: return 0 if n == 1 or n ==0: return 1 else: return self.climbStairs(n-1) + self.climbStairs(n-2)