create NEAT app repo

activation_order.rb

@@ -0,0 +1,42 @@
+#!/usr/bin/env ruby
+
+# BFS method
+def ao_bfs(net, cur_layer, seen=nil, order=nil)
+	# setup some state for this recursion
+	seen ||= Hash.new
+	order ||= Array.new
+
+	# mark current nodes as seen
+	cur_layer.each { |n| seen[n] = true }
+
+	# prepend current layer to final order
+	order = [cur_layer.sort] + order
+
+	# get next layer
+	next_layer = cur_layer.collect { |n| net[n] }
+	next_layer = next_layer.flatten.select { |n| not seen[n] }
+
+	if not next_layer.empty?
+		# recurse into next layer if it exists
+		ao_bfs(net, next_layer, seen, order)
+	else
+		# finished
+		order
+	end
+end
+
+# network format is a reverse digraph, so if node 0 feeds into node 1, you'd have 1 => [0]
+# ... in other words, node 1 directly depends upon node 0
+
+# 0,1,2 = inputs; 7,8,9 = outputs
+net = { 0 => [], 1 => [4], 2 => [], 3 => [0,4,5], 4 => [2,6], 5 => [1], 6 => [5], 7 => [3], 8 => [5], 9 => [6] }
+
+# call ao_bfs with output layer (or last layer)
+puts ao_bfs(net, [7,8,9]).inspect
+
+
+# DFS method
+# use DFS to find terminal nodes
+# as each terminal node is encountered, push it on the end of the order
+# and as each node becomes terminal node (i.e. all leaves explored), push it on
+