Sum of digits
Return the sum of all decimal digits of a non-negative integer.
Sum numbers from 1 to n
Implement a function that computes the sum of all integers from 1 to n.
Sum from 1 to n
Write a function that returns the sum of all integers from 1 to n (inclusive).
Perimeter of triangle
Given three side lengths, return the perimeter (sum) of the triangle.
Variadic Sum Function
Implement a variadic function that sums an arbitrary number of numeric arguments.
Cumulative Sum Vectorized
Implement a function that returns the cumulative sum of a list of numbers.
Two Sum
Return indices (i, j) with i < j such that nums[i] + nums[j] == target.
Count Adjacent Pairs
Given a list of integers and a target, count adjacent pairs whose sum equals the target.
Running Total Window
Implement a function that returns a list of running totals, resetting to zero after each positive sum.
Merge dicts summing values
Write a function that merges two dictionaries by summing values for duplicated keys.
Missing keys default zero
Write a function to sum numeric values from dictionaries, treating missing keys as zero.
Two Sum with Dict
Implement the classic Two Sum problem: return indices of two numbers that add up to a target using a dict.
Count Pairs with Sum
Implement a function that counts the number of distinct pairs in a list summing to a target.
Sum of divisors
Given an integer n, return the sum of all its positive divisors.
Perfect Number Check
Write a function that returns True if a number is perfect, i.e., equal to the sum of its proper divisors.
Abundant Number Check
Implement a function to check whether a given integer is abundant: sum of proper divisors exceeds the number.
Amicable Numbers Check
Write a function that checks if two numbers are an amicable pair by comparing sums of proper divisors.
Partition function
Write a function that returns the number of ways to write a positive integer as a sum of positive integers (order irrelevant).
Deficient Number Check
Write is_deficient(n) that returns True if the sum of proper divisors is less than n.
Subset XOR sum
Given a list of integers, compute the bitwise XOR of each non-empty subset and return the sum of those XOR totals.
House Robber
Given a list of house values, return the maximum sum you can rob without robbing two adjacent houses.
Triangle Minimum Path
Compute the minimum path sum from top to bottom of a triangle given as a list of lists.
Range Sum BST
Return the sum of all node values in a BST that lie within a given inclusive range [low, high].
Two Sum Sorted
Given a 1-indexed sorted array and a target, return the two indices that add up to the target.
Showing 1–24 of 30 challenges · easy
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.