Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.
1 <= nums.length <= 10^5-10^4 <= nums[i] <= 10^4k 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.
nums = [1,1,1,2,2,3], k = 2[1,2]nums = [1], k = 1[1]