0705-Design-HashSet.py

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

To be specific, your design should include these functions:

add(value): Insert a value into the HashSet. 
contains(value) : Return whether the value exists in the HashSet or not.
remove(value): Remove a value in the HashSet. If the value does not exist in the HashSet, do nothing.

Example:

MyHashSet hashSet = new MyHashSet();
hashSet.add(1);         
hashSet.add(2);         
hashSet.contains(1);    // returns true
hashSet.contains(3);    // returns false (not found)
hashSet.add(2);          
hashSet.contains(2);    // returns true
hashSet.remove(2);          
hashSet.contains(2);    // returns false (already removed)

Note:

All values will be in the range of [0, 1000000].
The number of operations will be in the range of [1, 10000].
Please do not use the built-in HashSet library.
'''
class MyHashSet:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.num_buckets = 15000
        self.buckets = [[] for _ in range(self.num_buckets)]
        
    def hash_function(self, key):
        return key % self.num_buckets

    def add(self, key: int) -> None:
        hash_key = self.hash_function(key)
        if not key in self.buckets[hash_key]:
            self.buckets[hash_key].append(key)
        

    def remove(self, key: int) -> None:
        hash_key = self.hash_function(key)
        if key in self.buckets[hash_key]:
            self.buckets[hash_key].remove(key)
        

    def contains(self, key: int) -> bool:
        """
        Returns true if this set contains the specified element
        """
        hash_key = self.hash_function(key)
        return True if key in self.buckets[hash_key] else False
        


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