70.爬楼梯（通过）Python

前9阶的解法分别是：1,2,3,5,8,13,21,34,55
由上可知，与Fibonacci sequence及其相似

class Solution:
    def climbStairs(self, n):
        """
        :type n: int
        :rtype: int
        """
        tmp = 1
        res = 2
        if n == 1:
            return 1
        elif n == 2:
            return 2
        else:
            for i in range(2,n):
                result = tmp + res
                tmp = res
                res = result
            return result