check.rb

class QueenCheck
  def self.safe_moves(q, k)
    z=->(p){q[0]==p[0]||q[1]==p[1]||(-7..7).map{|d|q.map{|x|x+d}}.include?(p)};z[k]?(t=[-1,0,1]).product(t).count{|a,b|(c=[k[0]+a,k[1]+b]).all?{|x|(1..8)===x}&&!z[c]}:-1
  end

  def self.safe_moves_explanation(queen_coords, king_coords)
    is_check = -> (king_coords) {
      return true if queen_coords[0] == king_coords[0] || queen_coords[1] == king_coords[1]

      (-7..7).map do |diagonal_move|
        [queen_coords[0] + diagonal_move, queen_coords[1] + diagonal_move]
      end.include?(king_coords)
    }

    return -1 unless is_check[king_coords]

    [-1,0,1].product([-1,0,1]).map do |move|
      [king_coords[0] + move[0], king_coords[1] + move[1]]
    end.count { |moved_coords|
      valid = moved_coords.all? { |coord| coord.between?(1,8)}
      valid && !is_check[moved_coords] }
  end
end