# easier and simpler

HASH_NUM = 524287

class MyHashSet:
    def __init__(self):

        self.tables = [0]*HASH_NUM

    def add(self, key: int) -> None:

        key = key%HASH_NUM
        self.tables[key] = 1

    def remove(self, key: int) -> None:
        key = key%HASH_NUM
        if self.tables[key]:
            self.tables[key] = 0
            return

        return

    def contains(self, key: int) -> bool:
        key = key%HASH_NUM
        return self.tables[key]



HASH_NUM = 2069

class Node:
    def __init__(self, val):
        self.val = val
        self.next = None

class MyHashSet:

    def __init__(self):

        self.tables = [None]*HASH_NUM

    def add(self, key: int) -> None:

        # address collision
        if self.tables[key%HASH_NUM]:
            current = self.tables[key%HASH_NUM]
            prev = current

            while current:
                if current.val == key:
                    return
                prev = current
                current = current.next
            prev.next = Node(key)

        self.tables[key%HASH_NUM] = Node(key)


    def remove(self, key: int) -> None:
        if self.tables[key%HASH_NUM]:
            current = self.tables[key%HASH_NUM]
            prev = current

            # if key matches at the head of the node
            if key == current.val:
                self.tables[key%HASH_NUM] = current.next
                return

            while current:
                if key == current.val:
                    prev.next = current.next
                    return
                prev = current
                current = current.next


    def contains(self, key: int) -> bool:

        current = self.tables[key%HASH_NUM]
        while current:
            if current.val == key:
                return True
            current = current.next

        return False


# Your MyHashSet object will be instantiated and called as such:
# obj = MyHashSet()
# obj.add(key)
# obj.remove(key)
# param_3 = obj.contains(key)