class Solution {
public:
    vector<int> intersect(vector<int>& nums1, vector<int>& nums2) {
        vector<int>res;
        unordered_map<int,int>hash;
        for(int i:nums1){
            hash[i]++;
        }
        
        for(int i:nums2){
            if(hash.find(i)!=hash.end()){
                res.push_back(i);
                hash[i]--;
                if(hash[i]==0)hash.erase(i);
            }
        }
        
        return res;
    }
};