Set

Implement a set data structure with the following methods:

• CustomSet() constructs a new instance of a set
• add(int val) adds val to the set
• exists(int val) returns whether val exists in the set
• remove(int val) removes the val in the set

This should be implemented without using built-in set.

Constraints

• n ≤ 100,000 where n is the number of calls to add, exists and remove

https://binarysearch.com/problems/Set

Examples

Example 1

Input

• methods = ['constructor', 'add', 'exists', 'remove', 'exists']
• arguments = [[], [1], [1], [1], [1]]

Output

• answer = [None, None, True, None, False]

Explanation

c = CustomSet()
c.add(1)
c.exists(1) == True
c.remove(1)
c.exists(1) == False

Solution