Book Allocation: Minimize Maximum Pages
Implement a function that returns the minimized maximum pages when allocating a list of books to k students.
Longest Substring Without Repeating Characters
Implement a function that returns the length of the longest substring without repeating characters.
Squares of Sorted Array
Implement a function that returns a sorted list of squares for a given non-decreasing integer array.
Boats to Save People – Two Pointer
Implement a function that returns the minimum number of boats needed to rescue everyone, given a weight limit and each boat carrying at most two people.
Kth Largest Element in an Array (Heap Edition)
Implement a function that returns the kth largest element in an unsorted integer array using a heap.
Join node values with arrows
Format string node values as 'a -> b -> c'; empty list returns ''.
Spiral Matrix Traversal
Implement a function that returns the elements of a 2D matrix in clockwise spiral order.
Diagonal Traverse Matrix
Implement a function that returns all elements of a matrix in diagonal zigzag order.
Transpose Matrix In-Place
Implement a function that transposes a square matrix in-place and returns the transposed matrix.
Matrix Multiply 2D
Write a function that multiplies two 2D matrices (lists of lists) and returns the product matrix.
Transpose 2D Array
Implement a function that returns the transpose of a rectangular 2D list.
Days in month
Write a function that returns the number of days in a given month and year, correctly handling leap years.
Days Between Dates
Write a function that returns the number of days between two given dates.
Weekday from date
Write a function that returns the full English weekday name for a date string.
Leap Years in Range
Write a function that returns a list of all leap years between two given years, inclusive.
Unix timestamp to datetime
Write a function that returns a UTC datetime string from a Unix timestamp.
Next Weekday Finder
Write a function that returns the next weekday date after a given date.
Schedule conflict check
Write a function that takes a list of time intervals and returns True if any two overlap.
Month End Date
Implement a function that returns the last day of the month for a given year and month.
Easter Date Calculator
Implement a function that returns the date of Easter Sunday for a given year using the Gregorian computus algorithm.
Parse email header
Write a function that parses a raw email header string and returns sender, recipient, and subject.
Inner Join Two Tables
Write a function that inner joins two lists of dictionaries on a common key and returns the combined rows.
Create Table Schema
Write a function that creates a SQLite table with a given name and columns, and returns the resulting schema as a list of column definitions.
Second highest salary
Given an employees table, write a SQL query that returns the second highest distinct salary, or NULL if it doesn't exist.
Showing 121–144 of 150 challenges
Guide: free Python coding challenges
Practice Python by solving problems
PythonSkillset challenges are hands-on coding exercises from beginner to advanced. Open a challenge, read the problem, write Python in the split-pane editor, and run tests with Pyodide — no install required.
How to use the arena
- Pick a category — basics, algorithms, strings, and more
- Open a challenge, read the statement, and edit the starter code
- Run tests, fix failures, then try a related quiz or tutorial lesson
Challenges vs tutorials and quizzes
Challenges test what you can build under constraints. For guided teaching, use our Python tutorials. For quick checks, try quizzes or copy snippets from code samples.