1481. 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

 

Solutions

Solution: Greedy

• Time complexity: O(nlogn)
• Space complexity: O(n)

 

JavaScript

/**
 * @param {number[]} arr
 * @param {number} k
 * @return {number}
 */
const findLeastNumOfUniqueInts = function (arr, k) {
  const countMap = arr.reduce((map, num) => {
    const count = map.get(num) ?? 0;

    return map.set(num, count + 1);
  }, new Map());
  const counts = [...countMap.values()];
  const size = counts.length;

  counts.sort((a, b) => a - b);

  for (let index = 0; index < size; index++) {
    k -= counts[index];
    if (k === 0) return size - index - 1;
    if (k < 0) return size - index;
  }
};