Top K Frequent Elements

Given an integer array nums and an integer k, return the k most frequent elements. You may return them in any order.

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Example 1

Input: nums = [1, 1, 1, 2, 2, 3], k = 2
Output: [1, 2]
Explanation: 1 appears 3 times and 2 appears 2 times - the two most frequent.

Example 2

Input: nums = [1], k = 1
Output: [1]
Explanation: There is only one element, which is trivially the most frequent.

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Constraints

• 1 <= nums.length <= 10^5
• -10^4 <= nums[i] <= 10^4
• k is in the range [1, the number of unique elements in nums]
• The answer is guaranteed to be unique.