Problem

Given a set of distinct integers, print the size of a maximal subset of  where the sum of any  numbers in is not evenly divisible by .
Input: arr[] = {3, 1, 4, 6, 5}
Output: 3
Subset with sum not divisible by 4 is {3, 1, 5}, with sum 9.

Solution

// Solution:
// The solution is to sort the array and then iterate through it.
// For each element, we check if the sum of the element and the previous element is divisible by k.
// If it is, we skip the element. If it isn't, we add it to the subset.
// This is optimal because we only iterate through the array once.

function maxSubset(arr, k) {
  arr.sort((a, b) => a - b);
  let subset = [];
  let prev = 0;
  for (let i = 0; i < arr.length; i++) {
    if ((arr[i] + prev) % k !== 0) {
      subset.push(arr[i]);
      prev = arr[i];
    }
  }
  return subset.length;
}

console.log(maxSubset([3, 1, 4, 6, 5], 4));