leetcode题目29. 两数相除

题目描述

给定两个整数，被除数 dividend 和除数 divisor。将两数相除，要求不使用乘法、除法和 mod 运算符。

返回被除数 dividend 除以除数 divisor 得到的商。

整数除法的结果应当截去（truncate）其小数部分，例如：truncate(8.345) = 8 以及 truncate(-2.7335) = -2

示例：

输入: dividend = 10, divisor = 3
输出: 3
解释: 10/3 = truncate(3.33333…) = truncate(3) = 3

python代码

class Solution:
    def divide(self, dividend: int, divisor: int) -> int:
        sign = (dividend > 0)^(divisor > 0)
        dividend = abs(dividend)
        divisor = abs(divisor)
        count = 0
        while dividend >= divisor:
            count += 1
            divisor <<= 1
        result = 0
        while count > 0:
            count -= 1
            divisor >>= 1
            if divisor <= dividend:
                result += 1<<count
                dividend -= divisor
        if sign: result = -result
        return result if -(1<<31) <= result <= (1<<31)-1 else (1<<31)-1

reference

​​https://leetcode-cn.com/problems/divide-two-integers/solution/xiao-xue-sheng-du-hui-de-lie-shu-shi-suan-chu-fa-b/​​