leetcode python 69. x 的平方根 70. 爬楼梯

两道非常非常水的题，第一题是知道python自带的x**y，表示求次方,第二题类似斐波那契数列的递推公式。

https://leetcode-cn.com/problems/sqrtx/description/
https://leetcode-cn.com/problems/climbing-stairs/description/

class Solution(object):
    def mySqrt(self, x):
        """
        :type x: int
        :rtype: int
        """
        y = x**0.5
        y= int(y)
        return y

class Solution(object):
    def climbStairs(self, n):
        """
        :type n: int
        :rtype: int
        """
        if n<=3:
            return n
        s = [1,2,3]
        for i in range(3,n):
            s.append(s[i-1]+s[i-2])
        return s[n-1]