Top K Frequent Elements
Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.
It is guaranteed that the answer is unique.
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 elements are 1 and 2.
Example 2:
Input: nums = [1], k = 1
Output: [1]
Explanation: There is only one element, so it is the most frequent.
Examples
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 elements are 1 and 2.
Example 2
Input: nums = [1], k = 1
Output: [1]
Explanation: There is only one element, so it is the most frequent.
Example 3
Input: nums = [4,4,4,1,1,2,2,2,3], k = 2
Output: [4,2]
Explanation: 4 appears 3 times and 2 appears 3 times. Both are among the top 2 most frequent.
Constraints
- -1 <= nums.length <= 10^5
- --10^4 <= nums[i] <= 10^4
- -k is in the range [1, the number of unique elements in the array]
- -It is guaranteed that the answer is unique
Optimal Complexity
Time
O(n)
Space
O(n)
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