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29. Divide Two Integers

Math Bit Manipulation

Problem - Divide Two Integers

Medium

Given two integers dividend and divisor, divide two integers without using multiplication, division, and mod operator.

The integer division should truncate toward zero, which means losing its fractional part. For example, 8.345 would be truncated to 8, and -2.7335 would be truncated to -2.

Return the quotient after dividing dividend by divisor.

Note: Assume we are dealing with an environment that could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For this problem, if the quotient is strictly greater than 231 - 1, then return 231 - 1, and if the quotient is strictly less than -231, then return -231.

 

Example 1:

Input: dividend = 10, divisor = 3
Output: 3
Explanation: 10/3 = 3.33333.. which is truncated to 3.

Example 2:

Input: dividend = 7, divisor = -3
Output: -2
Explanation: 7/-3 = -2.33333.. which is truncated to -2.

 

Constraints:

  • -231 <= dividend, divisor <= 231 - 1
  • divisor != 0

Solutions

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class Solution:
    def divide(self, dividend: int, divisor: int) -> int:
        if divisor == 1:
            return dividend
        if dividend == -(2**31) and divisor == -1:
            return (2**31) - 1

        sign = (dividend > 0 and divisor > 0) or (dividend < 0 and divisor < 0)
        dividend = -dividend if dividend > 0 else dividend
        divisor = -divisor if divisor > 0 else divisor
        result = 0

        while dividend <= divisor:
            val = divisor
            count = 1

            while val >= -(2**31) and dividend <= (val << 1): # << is bitwise shift left
                val <<= 1
                count <<= 1
            dividend -= val
            result += count

        return result if sign else -result

Submission Stats:

  • Runtime: 4 ms (6.45%)
  • Memory: 17.7 MB (68.11%)