#3375 - Minimum Operations to Make Array Values Equal to K

Problem Description

You are given an integer array nums and an integer k.

An integer h is called valid if all values in the array that are strictly greater than h are identical.

For example, if nums = [10, 8, 10, 8], a valid integer is h = 9 because all nums[i] > 9 are equal to 10, but 5 is not a valid integer.

You are allowed to perform the following operation on nums:

Select an integer h that is valid for the current values in nums.
For each index i where nums[i] > h, set nums[i] to h.

Return the minimum number of operations required to make every element in nums equal to k.

If it is impossible to make all elements equal to k, return -1.

Solution

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number}
 */
var minOperations = function(nums, k) {
  if (nums.some(x => x < k)) return -1;

  const uniqueAbove = [...new Set(nums.filter(x => x > k))].sort((a, b) => b - a);
  if (uniqueAbove.length === 0) return 0;

  let result = 0;
  let current = uniqueAbove.slice();

  while (current.length > 0) {
    const threshold = current[0] - 1;
    current = current.filter(x => x <= threshold);
    result++;
    if (current.every(x => x === k)) break;
  }

  return result;
};