Top K Frequent Elements

You get an array of integers nums and an integer k.

Return the k values that show up most often in nums, in any order.

How often a value shows up is its frequency. The tests always have one clear answer. Every value you return shows up more often than every value you leave out.

Example 1:

Input: nums = [5,3,5,8,3,5,2], k = 2
Output: [3,5]
Explanation: 5 shows up 3 times.
3 shows up twice.
8 and 2 show up once each.
The top 2 are 5 and 3. [5,3] is just as correct.

Example 2:

Input: nums = [9,9,9,9], k = 1
Output: [9]
Explanation: 9 is the only value.

Example 3:

Input: nums = [-2,6,-2,0,6,-2,6,1], k = 2
Output: [-2,6]
Explanation: -2 and 6 both show up 3 times.
0 and 1 show up once each.
A tie inside the answer is fine.
Only the values left out must show up less often.

Constraints:

• 1 to 100,000 numbers.
• Each number is from -10,000 to 10,000.
• k is at least 1 and at most the number of different values in nums.
• There is only one correct set of k values.