gistfile1.txt

def assert(phrase, val)
  puts (val && "p      #{phrase}" || "FAIL   #{phrase}")
end


@offsets = [[0,1], [1,0], [-1,1], [1,-1], [-1, 0], [0, -1], [1,1], [-1,-1]] 
world = {}

def neighbors_coordinates(coord)
  x,y = coord
  @offsets.map { |off|
    ox,oy = off
    [x + ox, y + oy]
  }
end

def live_neighbors(coord, world)
  neighbors_coordinates(coord).inject(0) { |count, currentCoord|
    count += 1 if world.has_key?(currentCoord); count
  }
end

def next_alive_val(coord, world)
  live_count = live_neighbors(coord, world)
  ((live_count == 2 || live_count == 3)) && 1 || nil
end

def next_dead_val(coord, world)
  live_count = live_neighbors(coord, world)
  (live_count == 3 && 1) || nil  
end

def next_val(coord, world)
  world.has_key?(coord) && next_alive_val(coord, world) || next_dead_val(coord, world)
end

assert("offsets have right length", @offsets.length == 8)
assert("neighbors_coordinates([0,0]) should == @offsets", neighbors_coordinates([0,0]) == @offsets)

assert("neighbors_coordinates([5,5]) should be correct", neighbors_coordinates([5,5])[3] == [6,4])

world = {
  [3,4] => 1,
  [5,4] => 1,
  [4,5] => 1,
  [5,5] => 1,
  [6,5] => 1,
  [0,0] => 1
}

assert("live_neighbors([5,6], world) == 3", live_neighbors([5,6], world))


assert("next_val([5,6], world) == 1", next_val([5, 6], world) == 1);
assert("next_val([6,4], world) == 1", next_val([6,4], world) == 1);
assert("next_val([0,0], world) == nil", next_val([0,0], world) == nil);


world1 = {
  [3,4] => 1,
  [5,4] => 1,
  [4,5] => 1
}

result_world = {
  [4,4] => 1
}

def do_coord(c, world)
  newVal = next_val(coord, world)
  newVal if newVal
end

def next_world(world)
  puts world.inspect
  world.keys.inject({ }){ |new_world, coord|
    puts coord.inspect + "__ " + next_val(coord, world).inspect
    newVal = next_val(coord, world)
    new_world[coord] = newVal if newVal
    neighbors_coordinates(coord).each do |c|
      puts c.inspect + "__ " + next_val(c, world).inspect
      newVal = next_val(c, world)
      new_world[c] = newVal if newVal
    end
    new_world
  }
end
puts "______"
next_world(world1).inspect

assert("next_world(world1) == right world", next_world(world1) == result_world )