#1018 - Binary Prefix Divisible By 5

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Problem Description

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.

Solution

/**
 * @param {number[]} nums
 * @return {boolean[]}
 */
var prefixesDivBy5 = function(nums) {
  const result = new Array(nums.length);

  for (let i = 0, current = 0; i < nums.length; i++) {
    current = (current * 2 + nums[i]) % 5;
    result[i] = current === 0;
  }

  return result;
};