Python实现"x的平方根"的两种方法

个人博客：https://sulenn.github.io/

 

实现int sqrt(int x)

计算并返回x的平方根，x为非负整数

返回向下取整的整数(不包含小数点)

Example 1:

Input: 4
Output: 2

Example 2:

Input: 8
Output: 2
Explanation: The square root of 8 is 2.82842..., and since 
             the decimal part is truncated, 2 is returned.

1：用int()加**（该题用range(x)的话会出现（memoryError）内存不足的情况）

def mySqrt(self, x):
        """
        :type x: int
        :rtype: int
        """
        return int(x**0.5)

2：二分法

def mySqrt(self, x):
        """
        :type x: int
        :rtype: int
        """
        low = 0
        mid = x // 2
        high = x
        while low <= high:           #注意判断条件
            if mid * mid > x:
                high = mid - 1
            elif mid * mid < x:
                low = mid + 1
            else:
                return mid
            mid = (low + high) // 2
        return mid          #向下取整

算法题来自：https://leetcode-cn.com/problems/sqrtx/description/