Divide Two Integers — LeetCode 29 Python Solution

The problem

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.

Example

Input

dividend = 10, divisor = 3

Output

3

Explanation

10/3 = 3.33333.. which is truncated to 3.

Python solution

class Solution:
    def divide(self, a: int, b: int) -> int:
        if b == 1:
            return a
        if a == -(2**31) and b == -1:
            return 2**31 - 1
        sign = (a > 0 and b > 0) or (a < 0 and b < 0)
        a = -a if a > 0 else a
        b = -b if b > 0 else b
        ans = 0
        while a <= b:
            x = b
            cnt = 1
            while x >= (-(2**30)) and a <= (x << 1):
                x <<= 1
                cnt <<= 1
            a -= x
            ans += cnt
        return ans if sign else -ans

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 29. Divide Two Integers is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

Related problems