Array Duplicate Finder | Dataford Interview Questions

Given an integer array nums, return all values that appear more than once. Each duplicate value should appear only once in the output, and the output may be returned in any order.

Write a function that scans the array and identifies repeated values efficiently.

Formal Specification

Input: A list of integers nums
Output: A list of integers containing every value that occurs at least twice in nums
If no duplicates exist, return an empty list
The order of returned values does not matter

Constraints

1 <= len(nums) <= 10^5
-10^9 <= nums[i] <= 10^9
Each duplicate value should appear only once in the output
The output order may be arbitrary

Function Signature

def find_duplicates(nums):

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