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LeastNumberOfUniqueIntegersAfterKRemovals.java
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LeastNumberOfUniqueIntegersAfterKRemovals.java
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package Leetcode;
import java.util.HashMap;
import java.util.Map;
import java.util.PriorityQueue;
/**
* @author kalpak
*
* 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
*
*/
public class LeastNumberOfUniqueIntegersAfterKRemovals {
public static int findLeastNumOfUniqueInts(int[] arr, int k) {
Map<Integer, Integer> map = new HashMap<>();
PriorityQueue<Integer> minHeap = new PriorityQueue<>((a, b) -> map.get(a) - map.get(b));
for(int i : arr) {
map.put(i, map.getOrDefault(i, 0) + 1);
}
minHeap.addAll(map.keySet());
// Remove from priorityQueue for k times
while(k > 0) {
k -= map.get(minHeap.poll());
}
// After k removal, priorityQueue contains the least number of unique integers.
return (k < 0) ? minHeap.size() + 1 : minHeap.size();
}
public static void main(String[] args) {
int[] arr = new int[]{4,3,1,1,3,3,2};
System.out.println(findLeastNumOfUniqueInts(arr, 3));
}
}