In-Place Array Filtering | Dataford Interview Questions

Write a function to filter or modify an array in-place, such as removing elements that repeat more than twice.

Implement keep_at_most_two(nums). Preserve the order of retained values, overwrite the beginning of nums in place, and return the new logical length k. Only nums[:k] is part of the result; values beyond that prefix do not matter. The input may be unsorted and may contain negative or repeated integers.

Function Contract

Input: a list of integers nums.
Output: an integer k, with each distinct value appearing no more than twice in nums[:k].

Constraints

0 <= len(nums) <= 10^4
-10^9 <= nums[i] <= 10^9
The original relative order of retained values must be preserved
Only nums[:k] is relevant after the function returns

Function Signature

def keep_at_most_two(nums):

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