705. Design HashSet

Easy

Design a HashSet without using any built-in hash table libraries.

Implement MyHashSet class:

• void add(key) Inserts the value key into the HashSet.
• bool contains(key) Returns whether the value key exists in the HashSet or not.
• void remove(key) Removes the value key in the HashSet. If key does not exist in the HashSet, do nothing.

Solution

class MyHashSet:
    def __init__(self):
        self.m = 100
        self.base = [[] for _ in range(self.m)]
        self.hash = lambda x: x % self.m

    def add(self, key: int) -> None:
        hashed = self.hash(key)
        if key not in self.base[hashed]:
            self.base[hashed].append(key)

    def remove(self, key: int) -> None:
        hashed = self.hash(key)
        if key in self.base[hashed]:
            self.base[hashed].remove(key)

    def contains(self, key: int) -> bool:
        hashed = self.hash(key)
        if key in self.base[hashed]:
            return True
        return False