2363-merge-similar-items.cpp

class Solution {
public:
    vector<vector<int>> mergeSimilarItems(vector<vector<int>>& items1, vector<vector<int>>& items2) {
        map<int, int> mp;
        for(int i = 0; i < items1.size(); i++)
            mp[items1[i][0]] = items1[i][1];
        for(int i = 0; i < items2.size(); i++){
            if(mp.find(items2[i][0]) != mp.end()) mp[items2[i][0]] += items2[i][1];
            else mp[items2[i][0]] = items2[i][1];
        }
        vector<vector<int>> res;
        for(auto it : mp){
            res.push_back({it.first,it.second});
        }
        return res;
    }
};