Perm and Queen in Ruby using the concept the OOP Polymorphism

polymorphism.rb

#
# Adrian Statescu <mergesortv@gmail.com>
# Object-oriented Programming Concept Polymorphism.
# A class enherits states and behavior from its superclass. Inheritance provides a powerful and natural mechanism for
# organizing and structuring software program.
# Polymorphism is ability to appear in many forms and it is to redefine methods for derivated classes.
# The languages's ability to process objects differently depending on their datatype and class

class Bkt

      def initialize(_n)
          @n = _n
          @stack = [0]*(_n+1)
          @level = 0         
      end 

      def init
          0  
      end

      def succ
          0
      end

      def valid
          0
      end 

      def sol
          0
      end 

      def print
          p @stack
      end   


      def back

          @level = 1

          self.init

          while @level > 0 do

                hs = 1

                iv = 0

                while hs==1 && iv==0 do

                      hs = self.succ

                      if hs

                         iv = self.valid

                      end 

                end     

                if hs == 1

                   if self.sol

                      self.print                        

                   else

                      @level = @level + 1 

                      self.init()  

                   end 

                else

                   @level = @level - 1 

                end
          end
                      
           
       end 
     
end

class Perm < Bkt

      def initialize(_n)
          super(_n) 
      end 

      def run
          self.back
      end

      def init
          @stack[@level] = 0
      end

      def succ
          if @stack[@level] < @n
             @stack[@level] += 1
             return 1  
          end
          return 0
      end

      def valid
          for i in 1..@level-1
              if @stack[i] == @stack[@level]
                 return 0
              end  
          end
          return 1
      end 

      def sol
          return @level == @n
      end 
end

class Queens < Perm

      def valid
          for i in 1..@level-1
              if @stack[i] == @stack[@level] || (@stack[i] - @stack[@level]).abs == (i - @level).abs
                 return 0
              end  
          end
          return 1
      end 

end

p = Perm.new(3)
p.run()
q = Queens.new(4)
q.run()