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Single Number

2022-01-25
Single Number Given a non-empty array of integers nums, every element appears twice except for one. Find that single one. Example 1: Input: nums = [2,2,1] Output: 1 Example 2: Input: nums = [4,1,2,1,2] Output: 4 Example 3: Input: nums = [1] Output: 1 Using a HashSet (linear space complexity) We can iterate nums and for each number n do the following: If this is the first time we’ve seen n, then we add n to a hashset If the hashset contains n, then n gets removed from the hashset: 1 2 3 4 5 6 7 8 def get_single_number(nums: List[int]) -> int: uniques = set() for n in nums: if n not in uniques: uniques.