EMP Grid Challenge

emp_grid.rb

# safe? should return true or false if the absolute coordinate digit sum is a multiple of 3
def safe?(x,y)
  # [true, false].sample
  # ([x, y].map(&:abs).to_s.chars.map(&:to_i).sum) % 3 == 0
  (x.abs + y.abs) % 3 == 0
end

def fill_cell(x, y)
  safe?(x,y) ? '■ ' : '□ '
end


def generate_grid(grid_base_size)
  grid_size = *(-(grid_base_size / 2)..(grid_base_size / 2))
  grid = "\n"
  grid_size.each do |x|
    row = ''
    grid_size.each do |y|
      col = fill_cell(x, y)
      row += col
    end
    grid += "#{row}\n"
  end
  print grid
end



generate_grid(30)



# There is a robot which can move around on a grid. The robot is placed at point (0,0) on a grid with positive and negative coordinate values.

# Some points are dangerous and contain EMP Mines. Create a map for the robot to avoid the EMP Mines.

# Mines are located the where the sum digits of abs(x) plus the sum of the digits of abs(y) are a multiple of 3. For example:
# The point (3, 2) is not safe because 3 + 2 = 5 and not a multiple of 3.
# The point (-1, -2) is safe because 1 + 2 = 3, which is a multiple of 3.