Python

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Python is a dynamic and strongly typed object-oriented programming language. It employs both duck typing and gradual typing (via type hints). It supports multiple programming paradigms including imperative (object-oriented, procedural) and declarative (functional, concurrent) flavors. But do not be fooled: while programming across paradigms is fully supported, everything in Python is an object.

Syllabus

Hello World

Exercism's classic introductory exercise. Just say "Hello, World!".

Guido's Gorgeous Lasagna

Learn the basics of Python by cooking Guido's Gorgeous Lasagna.

Ghost Gobble Arcade Game

Learn about bools by setting up the rules for the Ghost Gobble arcade game.

Currency Exchange

Learn about numbers by solving Chandler's currency exchange conundrums.

Meltdown Mitigation

Learn about conditionals and avoid a meltdown by developing a simple control system for a Nuclear Reactor.

Black Jack

Learn about comparisons by implementing some Black Jack judging rules.

Little Sister's Essay

Learn about string methods while improving your little sister's school essay.

Little Sister's Vocabulary

Learn about strings by helping your little sister with her vocabulary homework.

Card Games

Learn about lists by tracking hands in card games.

Chaitana's Colossal Coaster

Learn useful list methods helping Chaitana manage the lines for her colossal roller coaster.

Making the Grade

Learn about loops by grading and organizing your students exam scores.

Tisbury Treasure Hunt

Learn about tuples by helping out competitors in the Tisbury Treasure Hunt.

Inventory Management

Learn about dicts by managing warehouse inventory.

Mecha Munch Management

Learn about dictionary methods by building a shopping cart MVP for the Mecha Munch grocery app.

Locomotive Engineer

Learn about unpacking and multiple assignment in Python while helping Linus with his train control system.

Cater Waiter

Learn about sets by managing the menus and ingredients for your catering company's event.

Ellen's Alien Game

Learn about classes by creating an Alien for Ellen's game.

Plane Tickets

Learn about generators by assigning seats to passengers on Anaconda Airlines.

Leap

Determine whether a given year is a leap year.

Triangle

Determine if a triangle is equilateral, isosceles, or scalene.

Grains

Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.

Armstrong Numbers

Determine if a number is an Armstrong number.

Collatz Conjecture

Calculate the number of steps to reach 1 using the Collatz conjecture.

Bob is a lackadaisical teenager. In conversation, his responses are very limited.

Raindrops

Convert a number into its corresponding raindrop sounds - Pling, Plang and Plong.

Darts

Calculate the points scored in a single toss of a Darts game.

Perfect Numbers

Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for positive integers.

Reverse String

Reverse a given string.

Pangram

Determine whether a phrase uses every letter in the Latin alphabet.

Isogram

Determine whether a phrase is an isogram, a word with no repeated letters.

ISBN Verifier

Check if a given string is a valid ISBN-10 number.

Rotational Cipher

Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.

RNA Transcription

Given a DNA strand, return its RNA complement.

Resistor Color

Convert a resistor band's color to its numeric representation.

Resistor Color Duo

Convert color codes, as used on resistors, to a numeric value.

Resistor Color Trio

Convert color codes, as used on resistors, to a human-readable label.

Resistor Color Expert

Convert color codes as used on resistors with different bands to a human-readable label.

Secret Handshake

Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.

Anagram

Find the words that use the same letters as another word.

House

Output the nursery rhyme 'This is the House that Jack Built'.

Binary Search

Implement a binary search algorithm.

Hamming

Calculate the Hamming distance between two DNA strands.

Flatten Array

Take a nested list and return a single list with all values except nil/null.

Line Up

Help lining up customers at Yaʻqūb's Deli.

Difference of Squares

Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.

List Ops

Implement basic list operations.

Change the data format for scoring a game to more easily add other languages.

Space Age

Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.

Sum of Multiples

Given a number, find the sum of all the multiples of particular numbers up to but not including that number.

Gigasecond

Given a moment, determine the moment that would be after a gigasecond has passed.

Two Fer

Create a sentence of the form "One for X, one for me.".

Square Root

Given a natural radicand, return its square root.

Pig Latin

Implement a program that translates from English to Pig Latin.

Matching Brackets

Make sure the brackets and braces all match.

Sublist

Determine if a list is a sublist of another list.

Atbash Cipher

Create an implementation of the Atbash cipher, an ancient encryption system created in the Middle East.

Diamond

Given a letter, print a diamond starting with 'A' with the supplied letter at the widest point.

Eliud's Eggs

Help Eliud count the number of eggs in her chicken coop by counting the number of 1 bits in a binary representation.

Protein Translation

Translate RNA sequences into proteins.

Prime Factors

Compute the prime factors of a given natural number.

Given a number from 0 to 999,999,999,999, spell out that number in English.

Acronym

Convert a long phrase to its acronym.

Series

Given a string of digits, output all the contiguous substrings of length `n` in that string.

Run-Length Encoding

Implement run-length encoding and decoding.

Nth Prime

Given a number n, determine what the nth prime is.

Twelve Days

Output the lyrics to 'The Twelve Days of Christmas'.

Roman Numerals

Convert modern Arabic numbers into Roman numerals.

Word Count

Given a phrase, count the occurrences of each word in that phrase.

Scrabble Score

Given a word, compute the Scrabble score for that word.

Proverb

For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.

Luhn

Given a number determine whether or not it is valid per the Luhn formula.

D&D Character

Randomly generate Dungeons & Dragons characters.

Robot Name

Manage robot factory settings.

Phone Number

Clean up user-entered phone numbers so that they can be sent SMS messages.

Queen Attack

Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.

Transpose

Take input text and output it transposed.

Yacht

Score a single throw of dice in the game Yacht.

Conway's Game of Life

Implement Conway's Game of Life.

State of Tic-Tac-Toe

Determine the game state of a match of Tic-Tac-Toe.

Saddle Points

Detect saddle points in a matrix.

OCR Numbers

Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or whether it is garbled.

Robot Simulator

Write a robot simulator.

Grade School

Given students' names along with the grade that they are in, create a roster for the school.

Sieve

Use the Sieve of Eratosthenes to find all the primes from 2 up to a given number.

Pythagorean Triplet

Given an integer N, find all Pythagorean triplets for which a + b + c = N.

Circular Buffer

A data structure that uses a single, fixed-size buffer as if it were connected end-to-end.

Matrix

Given a string representing a matrix of numbers, return the rows and columns of that matrix.

High Scores

Manage a player's High Score list.

Kindergarten Garden

Given a diagram, determine which plants each child in the kindergarten class is responsible for.

Bottle Song

Produce the lyrics to the popular children's repetitive song: Ten Green Bottles.

Allergies

Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.

Simple Cipher

Implement the Vigenère cipher, a simple substitution cipher.

Poker

Pick the best hand(s) from a list of poker hands.

Wordy

Parse and evaluate simple math word problems returning the answer as an integer.

Crypto Square

Implement the classic method for composing secret messages called a square code.

Clock

Implement a clock that handles times without dates.

Rectangles

Count the rectangles in an ASCII diagram.

Simple Linked List

Write a simple linked list implementation that uses Elements and a List.

Tree Building

Refactor a tree building algorithm.

Connect

Compute the result for a game of Hex / Polygon.

All Your Base

Convert a number, represented as a sequence of digits in one base, to any other base.

Swift Scheduling

Convert delivery date descriptions to actual delivery dates.

Spiral Matrix

Given the size, return a square matrix of numbers in spiral order.

Variable Length Quantity

Implement variable length quantity encoding and decoding.

Change

Correctly determine change to be given using the least number of coins.

Killer Sudoku Helper

Write a tool that makes it easier to solve Killer Sudokus

Flower Field

Mark all the flowers in a garden.

Rail Fence Cipher

Implement encoding and decoding for the rail fence cipher.

Palindrome Products

Detect palindrome products in a given range.

Tournament

Tally the results of a small football competition.

Food Chain

Generate the lyrics of the song 'I Know an Old Lady Who Swallowed a Fly'.

Scale Generator

Generate musical scales, given a starting note and a set of intervals.

Largest Series Product

Given a string of digits, calculate the largest product for a contiguous substring of digits of length n.

Markdown

Refactor a Markdown parser.

Meetup

Calculate the date of meetups.

Pascal's Triangle

Compute Pascal's triangle up to a given number of rows.

Grep

Search a file for lines matching a regular expression pattern.

Linked List

Implement a doubly linked list.

Complex Numbers

Implement complex numbers.

Ledger

Refactor a ledger printer.

Hangman

Implement the logic of the hangman game using functional reactive programming.

Go Counting

Count the scored points on a Go board.

Forth

Implement an evaluator for a very simple subset of Forth.

Binary Search Tree

Insert and search for numbers in a binary tree.

Camicia

Simulate the card game and determine whether the match ends or enters an infinite loop.

Rational Numbers

Implement rational numbers.

Bowling

Score a bowling game.

Knapsack

Given a knapsack that can only carry a certain weight, determine which items to put in the knapsack in order to maximize their combined value.

Relative Distance

Given a family tree, calculate the degree of separation.

DOT DSL

Write a Domain Specific Language similar to the Graphviz dot language.

Custom Set

Create a custom set type.

Zebra Puzzle

Solve the zebra puzzle.

Affine Cipher

Create an implementation of the Affine cipher, an ancient encryption algorithm from the Middle East.

Word Search

Create a program to solve a word search puzzle.

Alphametics

Given an alphametics puzzle, find the correct solution.

Bank Account

Simulate a bank account supporting opening/closing, withdraws, and deposits of money. Watch out for concurrent transactions!

React

Implement a basic reactive system.

Zipper

Creating a zipper for a binary tree.

Two Bucket

Given two buckets of different size, demonstrate how to measure an exact number of liters.

Dominoes

Make a chain of dominoes.

Satellite

Rebuild binary trees from pre-order and in-order traversals.

Book Store

To try and encourage more sales of different books from a popular 5 book series, a bookshop has decided to offer discounts of multiple-book purchases.