Top N Frequent Elements | Dataford Interview Questions

KLA's eDR-7380 inspection workflow produces a list of integer event codes. Given the list and an integer n, return the n distinct event codes with the highest frequencies.

If two event codes have the same frequency, place the code that appears earlier in the input list first. The result must be ordered by decreasing frequency, then by first appearance.

Formal Specification

Implement top_n_frequent(nums, n), where nums is a non-empty list of integers and n is a positive integer no greater than the number of distinct values. Return a list containing exactly n distinct integers.

Aim for better than sorting all distinct values when n is much smaller than the number of distinct values.

Constraints

1 <= len(nums) <= 100,000
1 <= n <= number of distinct values in nums
-10^9 <= nums[i] <= 10^9
The output contains exactly n distinct values
Equal frequencies are ordered by first appearance

Function Signature

def top_n_frequent(nums, n):

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