from random import randrange
class RandomizedSet(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.list, self.pos = [], {}



    def insert(self, val):
        """
        Inserts a value to the set. Returns true if the set did not already contain the specified element.
        :type val: int
        :rtype: bool
        """
        if val in self.pos:
            return False
        else:
            self.list.append(val)
            self.pos[val] = len(self.list) - 1
            return True


    def remove(self, val):
        """
        Removes a value from the set. Returns true if the set contained the specified element.
        :type val: int
        :rtype: bool
        """
        # Replace it by self.list. Increases by 400 ms. Ideally both should have same number of elements.
        if val in self.pos:
            idx, last = self.pos[val], self.list[-1]
            self.list[idx], self.pos[last] = last, idx
            self.list.pop(); self.pos.pop(val, 0)
            return True
        return False


    def getRandom(self):
        """
        Get a random element from the set.
        :rtype: int
        """
        n = len(self.list)
        return self.list[random.randint(0,n-1)]




# 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()