O(1) Time Insert, Remove, and RemoveRandom Data Structure

linkedin Implement a class that supports the following operations in O(1) time complexity: add(val): Inserts an integer val. remove(val): Removes an integer val. removeRandom(): Removes a random integer. Assume all test cases' operations are valid, i.e., remove or removeRandom will not be called on an empty set. Example: add(1) add(2) removeRandom() remove(1) add(1) The above sequence of operations may result in a set with remaining value [1]. Example Input add(1) add(2) removeRandom() remove(1) add(1)