knight travails v2.rb

class KnightTravails

  def initialize size=8
    @size = size
    @board = Array.new(@size) { Array.new(@size)}
  end

  def knight_path start_node, end_node, forbidden_nodes
    mark_forbidden forbidden_nodes
    path = breadth_first_search start_node, end_node 
    print_path path
  end

  def mark_forbidden forbidden_nodes
    forbidden_nodes.each do |el|
      @board[ el[0].ord - 97 ][ Integer(el[1,1]) - 1 ] = :forbidden
    end
  end

  def  breadth_first_search start_node,end_node
    queue = [end_node]  #searches from end to start
    queue.each do |i,j|
      generate_new_moves(i,j).map do |k,l|
        queue << [k,l]
        return get_path(start_node,end_node) if [k,l] == start_node
      end
    end
    return false
  end

  def print_path path
    if path
      path.each do |i,j|
        print (i+97).chr
        puts j + 1  
      end
    else
      puts "Path not found"
    end  
  end
  
  def get_path start_node,end_node
    node = start_node
    path = [node]
    while node != end_node 
      node =  @board[node[0]][node[1]]
      path << node
    end
    path
  end

  def in_bounds? k,l
    k >= 0 && l >= 0 && k < @size && l < @size
  end

  def moves
    [[1,2],[-1,2],[1,-2],[-1,-2],
      [2,1],[-2,1],[2,-1],[-2,-1]]
  end

  def generate_new_moves i,j
    new_moves = moves.map do |k,l|
      [i+k, j+l]
    end.reject do |k,l| 
      !in_bounds?(k,l) || (@board[k][l] ) #marked or outside the board
    end
    new_moves.each do |k,l|
      #mark as used and store origin
      @board[k][l] = [i,j]
    end
    new_moves
  end
end

if __FILE__ == $0
  start_node, end_node,*forbidden = ARGV 
  start_node = [start_node[0].ord - 97, Integer(start_node[1,1]) - 1]
  end_node = [end_node[0].ord - 97, Integer(end_node[1,1]) - 1]
  KnightTravails.new.knight_path start_node, end_node, forbidden
end