Python Solution with Chaining - without boolean array (Explanation included)
\nclass ListNode:\n    def __init__(self, key, val):\n        self.key = key\n        self.val = val\n        self.next = None\n\nclass MyHashSet:\n\n    def __
```\nclass ListNode:\n    def __init__(self, key, val):\n        self.key = key\n        self.val = val\n        self.next = None\n\nclass MyHashSet:\n\n    def __init__(self):\n        """\n        Initialize your data structure here.\n        """\n        self.size = 1000\n        self.m = [None]*self.size\n\n    def add(self, key: int) -> None:\n        index = key%self.size\n        #If the node at given index is None then set it with given key\n        if self.m[index] == None:\n            self.m[index] = ListNode(key,True)\n        else:\n            currNode = self.m[index]\n            #If there are nodes at given index then traverse the linked-list and attach the key at the end.\n            tempHead = currNode\n            self.m[index] = ListNode(key,True)\n            self.m[index].next = currNode\n\n    def remove(self, key: int) -> None:\n        index = key%self.size\n        #If node at given index is None then do nothing. \n        if self.m[index] == None:\n            return\n        #Otherwise find given key in the linked-list at current index and set its value to False.\n        else:\n            currNode = self.m[index]\n            while currNode:\n                if currNode.key == key:\n                    currNode.val = False\n                    break\n                currNode = currNode.next\n        \n\n    def contains(self, key: int) -> bool:\n        """\n        Returns true if this set contains the specified element\n        """\n        index = key%self.size\n        #If there\'s no linked-list at given index then return False.\n        if self.m[index] == None:\n            return False\n        #Otherwise traverse the linked-list to check if the desired element is present and its value is True.\n        else:\n            currNode = self.m[index]\n            while currNode:\n                if currNode.key == key:\n                    if currNode.val == True:\n                        return True\n                    else:\n                        return False\n                currNode = currNode.next\n            return False\n```
['Python', 'Python3']