map_size_test.rb

M = 'land'
o = 'water'
 
world = [[o,o,o,o,o,o,o,o,o,o,o],
         [o,o,o,o,M,M,o,o,o,M,o],
         [o,o,o,M,M,M,M,o,o,M,o],
         [o,o,M,M,M,o,o,M,o,M,o],
         [o,M,M,M,o,o,o,o,o,o,o],
         [o,o,o,o,M,M,M,o,M,M,o],
         [o,M,o,M,M,o,o,o,o,o,o],
         [o,M,M,o,o,M,M,o,o,o,o],
         [o,M,M,M,M,M,o,o,o,M,o],
         [o,o,M,M,o,M,o,o,M,M,o],
         [o,o,o,o,M,M,o,o,o,o,o]]
 
def continent_size world, x, y
  if y > world.length-1 || x > world[y].length-1 || y < 0 || x < 0 # indices are out of bounds
    return 0
  elsif 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 tile...
  size = 1
  world[y][x] = 'counted land'
 
  # ...then we count all of the neighboring eight tiles
  # (and, of course, their neighbors by way of the recursion).
  size = size + continent_size(world, x-1, y)
  size = size + continent_size(world, x-1, y-1)
  size = size + continent_size(world, x-1, y+1)
  size = size + continent_size(world, x, y-1)
  size = size + continent_size(world, x, y+1)
  size = size + continent_size(world, x+1, y)
  size = size + continent_size(world, x+1, y-1)
  size = size + continent_size(world, x+1, y+1)
  size
end
 
puts continent_size(world, 5, 1)