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@KyleMit
Created Nov 16, 2014
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Conway's Game of Life
module Life
def self.next_grid live_cells_in_grid
new_grid = Set.new
potential_cells(live_cells_in_grid).each do |cell|
alive = live_cells_in_grid.include?(cell)
neighbors = live_neighbors_count(live_cells_in_grid, cell)
if next_state_alive(alive, neighbors)
new_grid << cell
end
end
new_grid
end
def self.potential_cells live_cells_in_grid
border_cells = []
live_cells_in_grid.each do |live_cell|
border_cells.concat border_cells(live_cell)
end
border_cells.concat live_cells_in_grid.to_a()
border_cells.uniq
end
def self.border_cells cell
border_cells = []
(-1..1).each do |x|
(-1..1).each do |y|
next if [x, y] == [0, 0]
border_cells << [cell[0] + x, cell[1] + y]
end
end
border_cells
end
def self.live_neighbors_count live_cells_in_grid, cell
c = 0
border_cells(cell).each do |border_cell|
c += 1 if live_cells_in_grid.include?(border_cell)
end
c
end
def self.next_state_alive initially_alive, num_neighbors
(initially_alive and num_neighbors == 2) or
(num_neighbors == 3)
end
end
require_relative 'life'
module Life
describe "an empty grid" do
subject { Set.new }
it "turns into another empty grid" do
next_grid = Life.next_grid(subject)
expect(next_grid.size).to eq(0)
end
end
describe "a grid with one live cell" do
subject do
grid = Set.new
grid << [42, 37]
end
it "turns into en empty grid" do
next_grid = Life.next_grid(subject)
expect(next_grid).to be_empty
end
end
describe "a grid with 3 live neighbors" do
subject do
grid = Set.new
grid << [1,1]
grid << [2,1]
grid << [2,2]
end
it "brings a cell to life" do
next_grid = Life.next_grid(subject)
expect(next_grid).to include([1,2])
end
it "preserves the live cells with 2 or 3 neighbors" do
next_grid = Life.next_grid(subject)
expect(next_grid).to include([1,1])
expect(next_grid).to include([2,1])
expect(next_grid).to include([2,2])
end
it "counts a cell's neighbors" do
expect(Life.live_neighbors_count(subject, [1,1])).to eq(2)
expect(Life.live_neighbors_count(subject, [0,0])).to eq(1)
expect(Life.live_neighbors_count(subject, [0,1])).to eq(1)
end
end
describe "a particular cell" do
subject { [5,5] }
it "should gather all the coordinates around it" do
expect(Life.border_cells(subject)).to match_array(
[[4,4],[4,5],[4,6],
[5,4], [5,6],
[6,4],[6,5],[6,6]])
end
end
end
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