Puzzle Fighter

This is a generic implementation of a Code Wars Kata called Puzzle Fighter in Ruby. In short it is a reimplementation of an engine from games like Super Puzzle Fighter II Turbo. One of the modern examples of such games is Crystal Crysis. Whole implementation is contained in one file app.rb due to the fact Code Wars requires inline solution.

While solving this Kata I was trying to avoid mutation as much possible. Every time new state change was introduced new representation of whole state of game board was created and returned with the change applied. This resulted in possibility to create command pipelines, like:

def call
  @blocks
    .then(&Rainbow)
    .then(&PowerCombiner)
    .then(&method(:crash_logic))
    .then(&PowerCombiner)
    .then(&PowerExpander)
    .then(&PowerMerger)
end

End result is quite slow. The pin-point of this solution is a calculation of largest rectangle-shaped subarea of the matrix. This is required to form Power Gems. It uses generic O(n²) alghoritm which is using whole board every time. There are better solutions, including some hacky optimisations which are possible in case of small, 6x12 matrix. Desipte this, with some trivial, ad-hoc caching tricks this solution managed to pass Code Wars test suite with limit of 12s in just about 8s seconds.

I encourage everyone to try to create own implementation. This task includes many intreresting caveats. It encourages patters, which are rarely used, if most of what you do on daily basis is Web development.