LeetCode 1481: Least Number of Unique Integers after K Removals Solution

Master LeetCode problem 1481 (Least Number of Unique Integers after K Removals), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

1481. Least Number of Unique Integers after K Removals

Medium

Array Hash Table Greedy Sorting Counting

Problem Explanation

Explanation

To solve this problem, we can follow these steps:

Count the frequency of each integer in the array.
Sort the integers based on their frequencies.
Remove the least frequent integers one by one until we have removed k elements.
Return the count of unique integers remaining after removal.

Time complexity: O(n log n) where n is the number of integers in the array. Space complexity: O(n) to store the frequency of each integer.

Solution Code

import java.util.*;

class Solution {
    public int findLeastNumOfUniqueInts(int[] arr, int k) {
        Map<Integer, Integer> freqMap = new HashMap<>();
        for (int num : arr) {
            freqMap.put(num, freqMap.getOrDefault(num, 0) + 1);
        }
        
        List<Integer> freqList = new ArrayList<>(freqMap.values());
        Collections.sort(freqList);
        
        int uniqueCount = freqList.size();
        int count = 0;
        for (int freq : freqList) {
            if (k >= freq) {
                k -= freq;
                count++;
            } else {
                break;
            }
        }
        
        return uniqueCount - count;
    }
}

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