Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.
Example 1:
Input: nums = [1,1,1,2,2,3], k = 2
Output: [1,2]
Example 2:
Input: nums = [1], k = 1
Output: [1]
Example 3:
Input: nums = [1,2,1,2,1,2,3,1,3,2], k = 2
Output: [1,2]
Constraints:
1 <= nums.length <= 105-104 <= nums[i] <= 104k is in the range [1, the number of unique elements in the array].
Follow up: Your algorithm's time complexity must be better than O(n log n), where n is the array's size.