Contents

require "solver_24/version"

class Solver_24
  attr_accessor :all_expressions, :solutions

  OPERATION_SET = ["+","-","/","*"].repeated_permutation(3).to_a

  def initialize 
    @all_expressions = []
    @solutions = []
  end

  def solve(a)                         
    make_possible_solutions(get_sets_of_numbers(a))
    find_solutions
    solutions
  end 

  def get_sets_of_numbers(a)
    a.permutation(4).to_a.tap do |numbers|
      numbers.each { |set| set.map!(&:to_f)}
    end
  end

  def make_possible_solutions(nums)
    expressions = []

    nums.each do |num|
      OPERATION_SET.each {|op| expressions << num.zip(op).flatten.compact}
    end 

    add_all_possible_order_of_ops(expressions)
  end

  def add_all_possible_order_of_ops(expressions)
    all_expressions.tap do |expos|
      expos << add_order_of_operations(expressions)
    end
  end
 
  def add_order_of_operations(expressions)
    [].tap do |temp_storage|  
      expressions.each do |exp|   
        temp_storage << exp.dup.insert(0, "(").insert(4, ")") 
        temp_storage << exp.dup.insert(0, "(").insert(6, ")")
        temp_storage << exp.dup.insert(2, "(").insert(8, ")")
        temp_storage << exp.dup.insert(4, "(").insert(8, ")")
        temp_storage << exp.dup.insert(0, "(").insert(4, ")").insert(6, "(").insert(10, ")") 
      end
    end
  end

  def find_solutions
    solutions.tap do |solutions|
      all_expressions.each do |wrapper|

        wrapper.each do |exp|
          value = eval(exp.join)
          solutions << exp.join(" ") if value == 24
        end
      end
    end
  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
solver_24-1.0.0	lib/solver_24.rb
solver_24-0.4.0	lib/solver_24.rb