2411-smallest-subarrays-with-maximum-bitwise-or.js

/**
 * 2411. Smallest Subarrays With Maximum Bitwise OR
 * https://leetcode.com/problems/smallest-subarrays-with-maximum-bitwise-or/
 * Difficulty: Medium
 *
 * You are given a 0-indexed array nums of length n, consisting of non-negative integers. For
 * each index i from 0 to n - 1, you must determine the size of the minimum sized non-empty
 * subarray of nums starting at i (inclusive) that has the maximum possible bitwise OR.
 * - In other words, let Bij be the bitwise OR of the subarray nums[i...j]. You need to find
 *   the smallest subarray starting at i, such that bitwise OR of this subarray is equal to
 *   max(Bik) where i <= k <= n - 1.
 *
 * The bitwise OR of an array is the bitwise OR of all the numbers in it.
 *
 * Return an integer array answer of size n where answer[i] is the length of the minimum sized
 * subarray starting at i with maximum bitwise OR.
 *
 * A subarray is a contiguous non-empty sequence of elements within an array.
 */

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var smallestSubarrays = function(nums) {
  const n = nums.length;
  const result = new Array(n).fill(1);
  const bitPositions = new Array(32).fill(0);

  for (let i = n - 1; i >= 0; i--) {
    for (let bit = 0; bit < 32; bit++) {
      if (nums[i] & (1 << bit)) {
        bitPositions[bit] = i;
      }
    }

    let maxIndex = i;
    for (let bit = 0; bit < 32; bit++) {
      maxIndex = Math.max(maxIndex, bitPositions[bit]);
    }

    result[i] = maxIndex - i + 1;
  }

  return result;
};