Java

Learn about booleans while helping Annalyn rescue her friend.

Learn about exception-handling by making a simple calculator.

Learn about characters and StringBuilder by cleaning strings.

Learn about classes by working on a remote controlled car.

Learn about numbers by analyzing the production of an assembly line.

Learn about switches by developing a system to report on soccer matches.

Learn about enums by parsing logs.

Learn about the null literal and nullable variables in java by printing name badges.

Learn about bit manipulation by writing a program to decrypt a message.

Learn about maps while managing international calling codes.

Determine whether a given year is a leap year.

Randomly generate Dungeons & Dragons characters.

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

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

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

Given a DNA strand, return its RNA complement.

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

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

Calculate the Hamming distance between two DNA strands.

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

Determine if a word or phrase is an isogram.

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

Detect saddle points in a matrix.

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

Keep track of time through a digital stopwatch.

Score a single throw of dice in the game Yacht.

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

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

Implement Conway's Game of Life.

Search a file for lines matching a regular expression pattern. Return the line number and contents of each matching line.

Refactor a ledger printer.

Implement a program that translates from English to Pig Latin.

Given a family tree, calculate the degree of separation.

Implement run-length encoding and decoding.

Given a natural radicand, return its square root.

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

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

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

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

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

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

Count the frequency of letters in texts using parallel computation.

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

Take input text and output it transposed.

Insert and search for numbers in a binary tree.

Implement a clock that handles times without dates.

Write a function to determine if a list is a sublist of another list.

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

Create a program to solve a word search puzzle.

Solve the zebra puzzle.

Creating a zipper for a binary tree.

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

Detect palindrome products in a given range.

Implement rational numbers.

Implement a basic reactive system.

Count the rectangles in an ASCII diagram.

Implement the Vigenère cipher, a simple substitution cipher.

Implement an evaluator for a very simple subset of Forth.

Create a custom set type.