Find Duplicates in Integer Array

Problem

Given an array of integers nums, return a list of 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. The input is a Python list of integers, and the output is a Python list of integers.

Constraints

• 1 <= len(nums) <= 10^5
• -10^9 <= nums[i] <= 10^9
• Return each duplicated value only once