69. Sqrt(x)刷题笔记

问题描述 用二分查找找平方根，应该可以用数论改进

class Solution:
    def mySqrt(self, x: int) -> int:
        if x<2:
            return x
        low = 0
        high = x//2
        mid = 0
        while low<=high:
            mid = (high+low)//2
            square = mid*mid
            if square<=x:
                low = mid+1
            else:
                high = mid-1
        return low-1