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 = 1Output:1Explanation: Remove the single 4, only 5 is left.

Input:arr = [4,3,1,1,3,3,2], k = 3Output:2Explanation: 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`

class Solution {
public int findLeastNumOfUniqueInts(int[] arr, int k) {
}
}