class Solution {
    public int[] topKFrequent(int[] nums, int k) {
        Map<Integer, Integer> map = new HashMap<>();
        /* If i is already in the function map, then increment i's value by 1 else, add i to map with value = 1*/
        for(int i: nums)
            map.merge(i, 1, Integer::sum);
        List<Integer> list = new ArrayList<>(map.keySet());
        /* Sort by values in descending order */
        list.sort((a, b) -> map.get(b) - map.get(a));
        /* Take sublist, convert to int[] */
       return list.subList(0, k).stream().mapToInt(Integer::intValue).toArray();
    }
}