What is a set in Python? How are values stored? How to find an element?

In Python, a set is an unordered collection of unique elements.

Storing values

A set is implemented based on a hash table. Each element is hashed, and its position in the data structure is determined by the hash. This provides fast access and set operations.

Element search

Searching for an element in a set occurs in amortized O(1) time thanks to hashing. When checking for the presence of an element, Python computes its hash and checks the corresponding slot.

Example usage

s = {1, 2, 3, 4}

# Adding an element
s.add(5)

# Checking for presence
if 3 in s:
    print("3 is in the set")

# Removing an element
s.remove(2)

print(s)  # Will output the set without 2

Sets are useful for removing duplicates, checking intersections, unions, and other operations on collections.