Implement the RandomizedSet class:


	RandomizedSet() Initializes the RandomizedSet object.
	bool insert(int val) Inserts an item val into the set if not present. Returns true if the item was not present, false otherwise.
	bool remove(int val) Removes an item val from the set if present. Returns true if the item was present, false otherwise.
	int getRandom() Returns a random element from the current set of elements (it's guaranteed that at least one element exists when this method is called). Each element must have the same probability of being returned.


You must implement the functions of the class such that each function works in&nbsp;average&nbsp;O(1)&nbsp;time complexity.

&nbsp;
Example 1:

Input
["RandomizedSet", "insert", "remove", "insert", "getRandom", "remove", "insert", "getRandom"]
[[], [1], [2], [2], [], [1], [2], []]
Output
[null, true, false, true, 2, true, false, 2]

Explanation
RandomizedSet randomizedSet = new RandomizedSet();
randomizedSet.insert(1); // Inserts 1 to the set. Returns true as 1 was inserted successfully.
randomizedSet.remove(2); // Returns false as 2 does not exist in the set.
randomizedSet.insert(2); // Inserts 2 to the set, returns true. Set now contains [1,2].
randomizedSet.getRandom(); // getRandom() should return either 1 or 2 randomly.
randomizedSet.remove(1); // Removes 1 from the set, returns true. Set now contains [2].
randomizedSet.insert(2); // 2 was already in the set, so return false.
randomizedSet.getRandom(); // Since 2 is the only number in the set, getRandom() will always return 2.


&nbsp;
Constraints:


	-231 &lt;= val &lt;= 231 - 1
	At most 2 *&nbsp;105 calls will be made to insert, remove, and getRandom.
	There will be at least one element in the data structure when getRandom is called.


class RandomizedSet:

    def __init__(self):
        self.data = set() 

    def insert(self, val: int) -> bool:
      if val not in self.data:
        self.data.add(val)
        return True 
      return False 
        
    def remove(self, val: int) -> bool:
        if val in self.data:
          self.data.remove(val)
          return True 
        return False 

    def getRandom(self) -> int:
        return  random.choice(list(self.data))
class RandomizedSet {
    HashMap<Integer, Integer> map;
    ArrayList<Integer> list;
    Random rand;
    public RandomizedSet() {
        map = new HashMap<>();
        list = new ArrayList<>();
        rand = new Random();
    }
    
    public boolean insert(int val) {
        if (!map.containsKey(val)){
            map.put(val, list.size());
            list.add(val);
            return true;
        }
        return false;
    }
    
    public boolean remove(int val) {
        if (map.containsKey(val)){
            int index = map.get(val);
            int last = list.get(list.size() - 1);
            if (index != list.size() - 1){
                list.set(index, last);
                map.put(last, index);
            }
            list.remove(list.size() - 1);  
            map.remove(val);
            return true;
        }
        return false;
    }
    
    public int getRandom() {
        int r = rand.nextInt(list.size());   
        return list.get(r);
    }
}
class RandomizedSet {
public:
    unordered_map<int, int> mp;
    vector<int> v;
    RandomizedSet() {
        
    }
    
    bool insert(int val) {
        if(mp.find(val) != mp.end()) return false;
        mp[val] = v.size();
        v.push_back(val);
        return true;
    }
    
    bool remove(int val) {
        if(mp.find(val) != mp.end()){
            v[mp[val]] = v.back();
            mp[v.back()] = mp[val];
            v.pop_back();
            mp.erase(val);
            return true;
        } 
        return false;
    }
    
    int getRandom() {
        return v[rand()%v.size()];
    }
};
var RandomizedSet = function() {
    this._data = [];
    this._flatData = [];
};

RandomizedSet.prototype.hash = function(val) {
    return val % 1e5;
}

RandomizedSet.prototype.insert = function(val) {
    const hash = this.hash(val);
    let basket = this._data[hash];
    
    for (let i = 0; i < basket?.length; i++) {
        if (basket[i][0] === val) { return false; }
    }
    
    if (!basket) {
        this._data[hash] = [[val, this._flatData.length]];
    } else {
        this._data[hash].push([val, this._flatData.length]);
    }
    this._flatData.push(val);    
    return true;
};

RandomizedSet.prototype.remove = function(val) {
    const hash = this.hash(val);
    let basket = this._data[hash];
    if (!basket) { return false; }
    for (let i = 0; i < basket.length; i++) {
        const currBasket = basket[i];
        if (currBasket[0] === val) {
            const idxInFlat = currBasket[1];
            const reassignedValueInFlat = del(this._flatData, idxInFlat);
            // Write new address in _data if needed
            if (reassignedValueInFlat) {
                this._data[this.hash(reassignedValueInFlat)].forEach(item => {
                    if (item[0] === reassignedValueInFlat) {
                        item[1] = idxInFlat;
                        return; // from forEach
                    }
                });
            }
            // Delete from _data
            del(basket, i);
            return true;
        }
    }
    return false;
};

RandomizedSet.prototype.getRandom = function() {
    return this._flatData[getRandomInt(0, this._flatData.length - 1)];
};

function getRandomInt(min, max) {
    min = Math.ceil(min);
    max = Math.floor(max);
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

function del(arr, idx) {
    if (!arr.length) { return null; }
    if (idx === arr.length - 1) { arr.pop(); return null; }
    arr[idx] = arr.pop();
    return arr[idx];
}
Insert Delete GetRandom O(1)