1748. Sum of Unique Elements

class Solution {
public:
    int sumOfUnique(vector<int>& nums) 
    {
        map<int, int> m;

        for(auto &val : nums)
        {
            m[val]++;
        }

        int sum = 0;

        for(auto &val : m)
        {
            if((val.second) == 1)
                sum += (val.first);
        }

        return sum;
    }
};