class RandomizedSet {
public:
    /** Initialize your data structure here. */

    unordered_map <int , int> idx_val;
    unordered_map <int , int> val_idx;
    int w = 0;
    RandomizedSet() {

    }

    /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
    bool insert(int val) {
        if (val_idx.count(val) > 0)
            return false;
        idx_val[w] = val;
        val_idx[val] = w;

        w++;

        return true;

    }

    /** Removes a value from the set. Returns true if the set contained the specified element. */
    bool remove(int val) {

        if (val_idx.count(val) == 0)
            return false;

        w--;

        int idx_del = val_idx[val];
        int val_w = idx_val[w];

        idx_val[idx_del] = val_w;
        val_idx[val_w] = idx_del;

        val_idx.erase(val);
        idx_val.erase(w);

        return true;


    }

    /** Get a random element from the set. */
    int getRandom() {


        return idx_val[rand() % w];
    }
};

/**
 * 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();
 */