Set (Hash-based)

A set implementation that uses a hash table to keep track of the unique elements.

Pros	Cons
Best amortized times for inserts/deletes	Bad hashing implementations or sizing can lead to linear times
	No ordering of elements

s = set()
s.add(10) # {10}
s.add(20) # {10, 20}
s.add(10) # {10}

s.remove(10) # {20}

Set<Integer> s = new HashSet<>();
s.add(10); // {10}
s.add(20); // {10, 20}
s.add(10); // {10, 20}

s.remove(10); // {20}

std:: unordered_set <int> s;

s.insert(10); // {10}
s.insert(20): // {10, 20}
s.insert(10); // {10, 20}

s.erase(10); // {20}