1748\. Sum of Unique Elements

Easy

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

Return _the **sum** of all the unique elements of_ `nums`.

**Example 1:**

**Input:** nums = [1,2,3,2]

**Output:** 4

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

**Example 2:**

**Input:** nums = [1,1,1,1,1]

**Output:** 0

**Explanation:** There are no unique elements, and the sum is 0.

**Example 3:**

**Input:** nums = [1,2,3,4,5]

**Output:** 15

**Explanation:** The unique elements are [1,2,3,4,5], and the sum is 15.

**Constraints:**

*   `1 <= nums.length <= 100`
*   `1 <= nums[i] <= 100`