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1071. Binary Prefix Divisible By 5

Array Bit Manipulation

Problem - Binary Prefix Divisible By 5

Easy

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).

  • For example, if nums = [1,0,1], then x0 = 1, x1 = 2, and x2 = 5.

Return an array of booleans answer where answer[i] is true if xi is divisible by 5.

 

Example 1:

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.
Only the first number is divisible by 5, so answer[0] is true.

Example 2:

Input: nums = [1,1,1]
Output: [false,false,false]

 

Constraints:

  • 1 <= nums.length <= 105
  • nums[i] is either 0 or 1.

Solutions

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

Submission Stats:

  • Runtime: 4 ms (62.16%)
  • Memory: 19 MB (88.42%)