least-number-of-unique-integers-after-k-removals

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1481. Least Number of Unique Integers after K Removals (Medium)

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

Related Topics

[Array] [Hash Table] [Greedy] [Sorting] [Counting]

Hints

Hint 1

Use a map to count the frequencies of the numbers in the array.

Hint 2

An optimal strategy is to remove the numbers with the smallest count first.