Palindrome Products

palindrome_products.rb

require 'pry'

class Palindromes
  attr_accessor :min_factor, :max_factor, :palindrome_factors, :palindromes

  def initialize(min_factor: 1, max_factor: 1)
    @min_factor, @max_factor = min_factor, max_factor
  end

  def generate
    @palindrome_factors = all_factor_combinations.select do |combination|
      product = combination[0] * combination[1]
      product.to_s == product.to_s.reverse
    end

    @palindromes = @palindrome_factors.map do |pair_of_factors|
      pair_of_factors[0] * pair_of_factors[1]
    end
  end

  def all_factor_combinations
    range = @min_factor.upto(@max_factor).to_a

    range.product(range.reverse)
  end

  def largest
    factors_for_largest_palindrome = @palindrome_factors.select do |pair_of_factors|
      pair_of_factors[0] * pair_of_factors[1] == @palindromes.max
    end

    Palindrome.new(@palindromes.max, factors_for_largest_palindrome)
  end

  def smallest
    factors_for_smallest_palindrome = @palindrome_factors.select do |pair_of_factors|
      pair_of_factors[0] * pair_of_factors[1] == @palindromes.min
    end

    Palindrome.new(@palindromes.min, factors_for_smallest_palindrome)
  end
end

class Palindrome
  attr_accessor :value, :largest_or_smallest_factors

  def initialize(value, largest_or_smallest_factors)
    @value = value
    @largest_or_smallest_factors = largest_or_smallest_factors
  end

  def factors
    @largest_or_smallest_factors
  end
end


palindromes = Palindromes.new(max_factor: 9)
palindromes.generate
largest = palindromes.largest
p largest.value
p largest.factors

palindromes = Palindromes.new(max_factor: 99, min_factor: 10)
palindromes.generate
largest = palindromes.largest
p largest.value
p largest.factors

palindromes = Palindromes.new(max_factor: 99, min_factor: 10)
palindromes.generate
smallest = palindromes.smallest
p smallest.value
p smallest.factors

palindromes = Palindromes.new(max_factor: 999, min_factor: 100)
palindromes.generate
largest = palindromes.largest
p largest.value
p largest.factors

palindromes = Palindromes.new(max_factor: 999, min_factor: 100)
palindromes.generate
smallest = palindromes.smallest
p smallest.value
p smallest.factors