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We also link to all the implementations of each exercise in other languages, which you can use for inspiration.
Correctly determine change to be given using the least number of coins
Simulate a bank account supporting opening/closing, withdraws, and deposits of money. Watch out for concurrent transactions!
Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.
Implement an evaluator for a very simple subset of Forth
Output the nursery rhyme 'This is the House that Jack Built'.
Implement a basic reactive system.
Compute the result for a game of Hex / Polygon
Tally the results of a small football competition.
Take input text and output it transposed.
Output the lyrics to 'The Twelve Days of Christmas'
Calculate the number of steps to reach 1 using the Collatz conjecture
Make a chain of dominoes.
Parallel Letter Frequency
Count the frequency of letters in texts using parallel computation.
Pick the best hand(s) from a list of poker hands.
Translate RNA sequences into proteins.
Variable Length Quantity
Implement variable length quantity encoding and decoding.
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.
Rail Fence Cipher
Implement encoding and decoding for the rail fence cipher.
Creating a zipper for a binary tree.
Reparent a graph on a selected node
Count the rectangles in an ASCII diagram.
Given the size, return a square matrix of numbers in spiral order.
Create a sentence of the form "One for X, one for me."
Create a program to solve a word search puzzle.
Diffie-Hellman key exchange.
Search a file for lines matching a regular expression pattern. Return the line number and contents of each matching line.
Generate musical scales, given a starting note and a set of intervals.
Implement various kinds of error handling and resource management
Refactor a Markdown parser
Parsing a Smart Game Format string.
Implement complex numbers.
Write a Domain Specific Language similar to the Graphviz dot language
Count the scored points on a Go board.
Implement the logic of the hangman game using functional reactive programming.
Refactor a ledger printer.
Use lenses to update nested records (specific to languages with immutable data).
Refactor a tree building algorithm.
Report network IO statistics