Binary Prefix Divisible By 5 — LeetCode 1018 Python Solution

The problem

You are given a binary array nums (0-indexed). We define xi as the number whose binary representation is the subarray nums[0..i] (from most-significant-bit to least-significant-bit).

Example

Input

nums = [0,1,1]

Output

[true,false,false]

Explanation

The input numbers in binary are 0, 01, 011; which are 0, 1, and 3 in base-10.

Python solution

class Solution:
    def prefixesDivBy5(self, nums: List[int]) -> List[bool]:
        ans = []
        x = 0
        for v in nums:
            x = (x << 1 | v) % 5
            ans.append(x == 0)
        return ans

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 1018. Binary Prefix Divisible By 5 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.

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