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  • 70. Climbing Stairs

    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)
    

      

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  • 原文地址:https://www.cnblogs.com/xqn2017/p/8006862.html
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