GFG PTOD | 29 DEC | Intersection of Two arrays with Duplicate Elements

vector<int> intersectionWithDuplicates(vector<int>& a, vector<int>& b) {
        // code here
        vector<int> res;
        unordered_set<int> s(a.begin(), a.end());
        for(int j = 0; j<b.size(); j++) {
            if(s.find(b[j]) != s.end()) {
                res.push_back(b[j]);
                s.erase(b[j]);
            }
        }
        return res;
    }