Design HashSet — LeetCode 705 Python Solution

The problem

Design a HashSet without using any built-in hash table libraries. Implement MyHashSet class: void add(key) Inserts the value key into the HashSet.

Example

Input

["MyHashSet", "add", "add", "contains", "contains", "add", "contains", "remove", "contains"]

Output

[null, null, null, true, false, null, true, null, false]

Explanation

MyHashSet myHashSet = new MyHashSet();

Python solution

class MyHashSet:
    def __init__(self):
        self.data = [False] * 1000001

    def add(self, key: int) -> None:
        self.data[key] = True

    def remove(self, key: int) -> None:
        self.data[key] = False

    def contains(self, key: int) -> bool:
        return self.data[key]


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

Complexity

Pattern: Linked List

Rewire pointers in place, with a dummy head and a saved next to keep it safe. LeetCode 705. Design HashSet is filed here because LeetCode tags it Linked List, which is the vocabulary this hub collects.

The linked list guide has the Python template for the pattern and the 75 LeetCode problems that use it.

Related problems