import java.util.*;

class Solution {
    public int[] topKFrequent(int[] nums, int k) {
        // Count frequency of each element
        Map<Integer, Integer> freq = new HashMap<>();
        for (int num : nums) {
            freq.put(num, freq.getOrDefault(num, 0) + 1);
        }

        // Create a list of frequency buckets
        List<Integer>[] buckets = new ArrayList[nums.length + 1];
        for (int num : freq.keySet()) {
            int count = freq.get(num);
            if (buckets[count] == null) {
                buckets[count] = new ArrayList<>();
            }
            buckets[count].add(num);
        }

        // Extract top k elements from frequency buckets
        int[] result = new int[k];
        int index = 0;
        for (int i = buckets.length - 1; i >= 0 && index < k; i--) {
            if (buckets[i] != null) {
                for (int num : buckets[i]) {
                    result[index++] = num;
                    if (index == k) {
                        break;
                    }
                }
            }
        }

        return result;
    }
}