Remove duplicates from a list of integers
Input
[3, 1, 2, 3]
Output
[1, 2, 3]
Convert the list to a set to get {1,2,3} then return it as a sorted list [1,2,3].
Full lesson preview
Create and use a set
Learn how to create a set from a collection to get unique items and return them in a deterministic order.
Python practice6 minDictionaries & SetsBeginnerLast updated March 18, 2026
Problem statement
Given a collection (list) of comparable, hashable items, create a set of unique items and return the unique items as a sorted list. Use Python's set type to remove duplicates. Sorting the result makes the output deterministic for testing and presentation.
Task
Convert a list-like collection into a set to remove duplicates, then return the unique items sorted.
Examples
Input format
A single list of comparable, hashable items (e.g., integers or strings).
Output format
A sorted list containing the unique items from the input.
Constraints
All items in the input list are hashable and of a type that can be compared with sorted (e.g., all ints or all strings).
Samples
Sample 1
Input
[3, 1, 2, 3]
Output
[1, 2, 3]
Duplicates removed, then sorted.