Battleship CodeKata 🚢💥

Welcome! Your assignment is to create a simple program that emulates the classic game Battleship.

Just in case you've never played this game before (shame on you!) let's go through the rules quickly.

Rules of the Game 📜

• Two players play the game, each taking turns
• Players have five ships:
  • an Aircraft Carrier
  • a Battleship
  • a Submarine
  • a Cruiser
  • a Destroyer
• Players have a grid or "ocean" where they arrange their ships
  • The grid is 10 x 10
  • The X-axis runs from A to J
  • The Y-axis goes from 1 to 10
  • Any square in the grid can be identified by combining these, for example B-3 is the square second from the left and third from the top
• After arranging the ships, they cannot be moved
• Ships occupy space on the grid, specific to the type of ship:
  • the Aircraft Carrier takes 5 squares
  • the Battleship takes 4 squares
  • the Submarine takes 3 squares
  • the Cruiser takes 3 squares
  • the Destroyer takes 2 squares
• A ship can only be positioned vertically or horizontally on the grid
• A ship cannot overlap other ships, or be placed outside of the grid
• Each round, each player takes a shot, announcing which square on the opponent's grid got hit
• The opposing player announces whether the shot hit or missed any of his ships
• When all squares of a ship are hit, the player announces it was sunk, including which ship it was
• The first player to sink all of his opponent's ships wins
• If both players eliminate all the opponent's ships in the same round, the game ends in a draw

Still want more info on the game? Check out this step-by-step guide.

Hints 💡

• How will you model the Grid? Does it need to be multidimensional?
• Can you make the language enforce correct (programmatic) inputs into the core domain?
• In what way can you leverage datastructures to your advantage?

Bonus Challenges 🥵

• Implement the entire core domain immutably
• Also tell the players which squares they already hit on the opponent's grid
• Allow players to automatically place their ships randomly on their grid
• Implement a bot to allow single-player mode
  • Start off simple, let the bot shoot random squares
  • Let the bot only shoot squares he has not hit yet
  • ...
• Implement spectator mode where two bots duke it out

Additional Notes 📝

You can implement the game as simple, or hard as you want to! From running the game with a test suite to text-based to a graphical interface. Go nuts!

Focus on learning, not on the results. Above all: have fun!

Contribute 🙋

Have ideas to make this Kata better? Maybe you found a typo, or grammar issue? Or how about a new idea that can make the Kata more interesting? Let me know!