[LeetCode 347] Top K Frequent Elements

Given a non-empty array of integers, return the k most frequent elements.

For example, Given [1, 1, 1, 2, 2, 3] and k = 2, return [1, 2].

Note:

• You may assume k is always valid, 1 ≤ k ≤ number of unique elements.
• Your algorithm's time complexity must be better than O(n log n), where n is the array's size.

Diffculty
Medium

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Analysis