Solution.py

class RandomizedSet:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.m = {}
        self.l = []

    def insert(self, val: int) -> bool:
        """
        Inserts a value to the set. Returns true if the set did not already contain the specified element.
        """
        if val in self.m:
            return False
        self.m[val] = len(self.l)
        self.l.append(val)
        return True

    def remove(self, val: int) -> bool:
        """
        Removes a value from the set. Returns true if the set contained the specified element.
        """
        if val not in self.m:
            return False
        idx = self.m[val]
        last_idx = len(self.l) - 1
        self.m[self.l[last_idx]] = idx
        self.m.pop(val)
        self.l[idx] = self.l[last_idx]
        self.l.pop()
        return True

    def getRandom(self) -> int:
        """
        Get a random element from the set.
        """
        return random.choice(self.l)


# Your RandomizedSet object will be instantiated and called as such:
# obj = RandomizedSet()
# param_1 = obj.insert(val)
# param_2 = obj.remove(val)
# param_3 = obj.getRandom()