1748. Sum of Unique Elements

 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

In JS:

var sumOfUnique = function(nums) {

    var sum = 0;

    // iterate over the array element and filter out

    var res = nums.filter(function(v) {

      // filter out only elements where both last 

      // index and first index are the same.

    return nums.indexOf(v) == nums.lastIndexOf(v);

});

for(let i=0; i<res.length; i++){

  sum = sum + res[i];

}

return sum

};