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Given a non-empty array of integers, return the k most frequent elements.
Example 1:
Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2]
Example 2:
Input: nums = [1], k = 1 Output: [1]
*Note: *
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You may assume k is always valid, 1 ≤ k ≤ number of unique elements.
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Your algorithm’s time complexity must be better than O(n log n), where n is the array’s size.
link:{sourcedir}/_0347_TopKFrequentElements.java[role=include]