Implement theRandomizedSetclass:

• bool insert(int val)Inserts an itemvalinto the set if not present. Returnstrueif the item was not present,falseotherwise.
• bool remove(int val)Removes an item from the set if present. Returns if the item was present,falseotherwise.
• 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 thesame probabilityof being returned.

Follow up:Could you implement the functions of the class with each function works onaverageO(1)time?

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.