class RandomizedSet {
    map<int, int> mp;
    vector<int> v;

public:
    /** Initialize your data structure here. */
    RandomizedSet() {
        
    }
    
    /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
    bool insert(int val) {
        if(mp.find(val) == mp.end()){
                
                v.push_back(val);
                mp[val] = v.size()-1;
            return true;
        }
        else return false;
    }
    
    /** Removes a value from the set. Returns true if the set contained the specified element. */
    bool remove(int val) {
        if(mp.find(val) == mp.end()){
            return false;
        }
        else{
             int idx = mp[val];
             mp.erase(val);
             swap(v[idx], v[v.size()-1]);
             v.pop_back();
            if(mp.size()!=0) mp[v[idx]] = idx;

             return true;
        }
    }
    
    /** Get a random element from the set. */
    int getRandom() {
        if(v.size() == 0) return 0;
        int rndm = rand()%v.size();
        return v[rndm];
    }
};

/**
 * Your RandomizedSet object will be instantiated and called as such:
 * RandomizedSet* obj = new RandomizedSet();
 * bool param_1 = obj->insert(val);
 * bool param_2 = obj->remove(val);
 * int param_3 = obj->getRandom();
 */

        if(mp.find(val) == mp.end()){
            return false;
        }
        else{
             int idx = mp[val];

             swap(v[idx], v[v.size()-1]);
             v.pop_back();
             mp[v[idx]] = idx;
             mp.erase(val);
             return true;
        }