Least Number of Unique Integers after K Removals

Description

Given an array of integers arr and an integer k. Find the least number of unique integers after removing exactly k elements.

 

Example 1:

Input: arr = [5,5,4], k = 1
Output: 1
Explanation: Remove the single 4, only 5 is left.

Example 2:

Input: arr = [4,3,1,1,3,3,2], k = 3
Output: 2
Explanation: Remove 4, 2 and either one of the two 1s or three 3s. 1 and 3 will be left.

 

Constraints:

• 1 <= arr.length <= 10^5
• 1 <= arr[i] <= 10^9
• 0 <= k <= arr.length

Solution(javascript)

/**
 * @param {number[]} arr
 * @param {number} k
 * @return {number}
 */
const findLeastNumOfUniqueInts = function (arr, k) {
  const map = {}

  for (const num of arr) {
    map[num] = map[num] || 0
    map[num] += 1
  }
  const keys = Object.keys(map).sort((a, b) => map[a] - map[b])
  for (const key of keys) {
    while (map[key] > 0 && k > 0) {
      k--
      map[key] -= 1
      if (map[key] === 0) {
        delete map[key]
      }
    }
  }
  return Object.keys(map).length
}