Chris Pine's Civilization problem

civ.rb

# These are just to make the map easier to read
# "M" is visually more dense than "o"

M = 'land'
o = 'water'

world = [[o,o,o,o,o,M,o,o,o,o,o],
         [o,o,o,o,M,M,o,o,o,o,o],
	 [o,o,o,o,o,M,o,o,M,M,o],
	 [o,o,o,M,o,M,o,o,o,M,o],
	 [o,o,o,M,o,M,M,o,o,o,o],
	 [o,o,o,o,M,M,M,M,o,o,o],
	 [o,o,o,M,M,M,M,M,M,M,M],
	 [o,o,o,M,M,o,M,M,M,o,o],
	 [o,o,o,o,o,o,M,M,o,o,o],
	 [o,M,o,o,o,M,o,o,o,o,o],
	 [o,o,o,o,o,o,o,o,o,o,o]]

def continent_size(world, x, y)
  if world[y][x] != 'land'
# Either it's water or we already
# counted it, but either way, we don't
# want to count it now
    return 0
  end

# So first we count this title... 
  size = 1
  world[y][x] = 'counted land'

# ...then we count all of the 
# neighboring eight tiles (and,
# of course, their neighbors by
# way of recursion)
	
  size += continent_size(world, x-1, y-1)
  size += continent_size(world, x  , y-1)
  size += continent_size(world, x+1, y-1)
  size += continent_size(world, x-1, y  )
  size += continent_size(world, x+1, y  )
  size += continent_size(world, x-1, y+1)
  size += continent_size(world, x  , y+1)
  size += continent_size(world, x+1, y+1)

  size
end
#puts continent_size(world, 5, 0)