Sum of Unique Elements — LeetCode 1748 Python Solution

The problem

You are given an integer array nums. The unique elements of an array are the elements that appear exactly once in the array.

Example

Input

nums = [1,2,3,2]

Output

4

Explanation

The unique elements are [1,3], and the sum is 4.

Python solution

class Solution:
    def sumOfUnique(self, nums: List[int]) -> int:
        cnt = Counter(nums)
        return sum(x for x, v in cnt.items() if v == 1)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1748. Sum of Unique Elements is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table and Counting.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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