(Js) Leetcode 1748. The sum of unique elements

topic:

Gives you an integer array nums. The only elements in the array are those that only appear exactly once.

Please return the sum of the only elements in nums.

Example 1:

Input: nums = [1,2,3,2]
Output: 4
Explanation: The only element is [1,3] and the sum is 4.
Example 2:

Input: nums = [1,1,1,1,1]
Output: 0
Explanation: There is no unique element, and the sum is 0.
Example 3:

Input: nums = [1,2,3,4,5]
Output: 15
Explanation: The only element is [1,2,3,4,5], and the sum is 15.

prompt:

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

Ideas:

1. Traverse the array for the first time, first count the number of occurrences of each element

2. Traverse the map for the second time and sum

Code:

/**
 * @param {number[]} nums
 * @return {number}
 */
var sumOfUnique = function (nums) {
    let map = new Map(), sum = 0;
    nums.forEach(item => {
        let count = map.get(item) || 0;
        map.set(item, ++count)
    });

    for(let [key, value] of map) {
        if(value === 1) {
            sum += key;
        }
    }
    return sum;
};

operation result: