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1748. Sum of Unique Elements

Given an array of integers, only sum the ones that appear once. Use a Counter from the collections
module to count occurrences. Use list comprehension to retain unique numbers - sum the list.

The solution is as follows:

  from collections import Counter

  class Solution:
      def sumOfUnique(self, nums: List[int]) -> int:
          counts = Counter(nums)
          return sum([num for num in counts if counts[num] < 2])

_ Time Complexity:

  O(n) - We iterate through the array to count all the integers.

_ Space Complexity:

  O(n) - We store the count of each interger.