Battleship

The game

Long version: see wikipedia

• Each player starts with a fleet of 5 ships, of length 5, 4, 3, 3, and 2.
• Each player places their ships horizontally or vertically on a 10x10 grid; this is not visible to their opponent.
• Players take turns to fire at positions on the grid, gradually revealing where their opponent’s ships are and are not located.
• A ship is destroyed when every cell of a ship has been hit.
• The winner is the first player to destroy their opponent’s fleet.

You lose if:

• You do not place the correct number and size of ships.
• You place your fleet in impossible positions (ships overlapping or partly off the board).
• Your code raises an exception.
• All your ships have been sunk.

TECHNOLOGIES

• HTML
• Javascript
• CSS

HOW TO PLAY

Will Add soon

state is a representation of the known state of the opponent’s fleet, as modified by the player’s shots. It is given as an array of arrays; the inner arrays represent horizontal rows. Each cell may be in one of three states: :unknown, :hit, or :miss. E.g.

[[:hit, :miss, :unknown, ...], [:unknown, :unknown, :unknown, ...], ...]
# 0,0   1,0    2,0              0,1       1,1       2,1

ships_remaining is an array of the ships remaining on the opponent's board, given as an array of numbers representing their lengths, longest first. For example, the first two calls will always be:

[5, 4, 3, 3, 2]

If the player is lucky enough to take out the length 2 ship on their first two turns, the third turn will be called with:

[5, 4, 3, 3]

and so on.

take_turn must return an array of co-ordinates for the next shot. In the example above, we can see that the player has already played [0,0], yielding a hit, and [1,0], giving a miss. They can now return a reasonable guess of [0,1] for their next shot.

The console runner

A console runner is provided. It can be started using:

bundle exec bin/play path/to/player_a.rb path/to/player_b.rb

Players are isolated using DRb.

A couple of very basic players are supplied: NaivePlayer and AnotherNaivePlayer put all their ships in a corner and guess at random (often wasting turns by repeating themselves). HumanPlayer asks for input via the console.