day 20

day20/part1.lua

@@ -0,0 +1,64 @@
+#!/usr/bin/env luajit
+require("utils")
+require("grid")
+
+local f = io.open(arg[3])
+local line = f:read("*l")
+local enhancer = {}
+for char in chars(line) do
+	if char == "#" then
+		table.insert(enhancer, 1)
+	else
+		table.insert(enhancer, 0)
+	end
+end
+f:read("*l")
+line = f:read("*l")
+local image = grid(1, 1, #line, #line, 0)
+local r, c = 0, 0
+while line ~= nil do
+	r = r + 1
+	c = 0
+	for char in chars(line) do
+		c = c + 1
+		if char == "#" then
+			image:set(r, c, 1)
+		end
+	end
+	line = f:read("*l")
+end
+
+function zoom(image, enhancer)
+	local newdefault = enhancer[image.default * (#enhancer - 1) + 1]
+	local newimage = grid(image.top - 1, image.left - 1,
+		image.height + 2, image.width + 2, newdefault)
+	for v, r, c in image:iter() do
+		newimage:set(r, c, v)
+	end
+	return newimage
+end
+
+function enhance(image, enhancer)
+	local newimage = zoom(image, enhancer)
+	for _, r, c in newimage:iter() do
+		local index = 0
+		for v, _, _ in image:neigh9(r, c) do
+			index = index * 2 + v
+		end
+		newimage:set(r, c, enhancer[index + 1])
+	end
+	return newimage
+end
+
+local function pprint(c)
+	if c == 0
+	then return "."
+	else return "#"
+	end
+end
+
+local counter = 0
+for v in enhance(enhance(image, enhancer), enhancer):iter() do
+	counter = counter + v
+end
+print(counter)

day20/part2.lua

@@ -0,0 +1,68 @@
+#!/usr/bin/env luajit
+require("utils")
+require("grid")
+
+local f = io.open(arg[3])
+local line = f:read("*l")
+local enhancer = {}
+for char in chars(line) do
+	if char == "#" then
+		table.insert(enhancer, 1)
+	else
+		table.insert(enhancer, 0)
+	end
+end
+f:read("*l")
+line = f:read("*l")
+local image = grid(1, 1, #line, #line, 0)
+local r, c = 0, 0
+while line ~= nil do
+	r = r + 1
+	c = 0
+	for char in chars(line) do
+		c = c + 1
+		if char == "#" then
+			image:set(r, c, 1)
+		end
+	end
+	line = f:read("*l")
+end
+
+function zoom(image, enhancer)
+	local newdefault = enhancer[image.default * (#enhancer - 1) + 1]
+	local newimage = grid(image.top - 1, image.left - 1,
+		image.height + 2, image.width + 2, newdefault)
+	for v, r, c in image:iter() do
+		newimage:set(r, c, v)
+	end
+	return newimage
+end
+
+function enhance(image, enhancer)
+	local newimage = zoom(image, enhancer)
+	for _, r, c in newimage:iter() do
+		local index = 0
+		for v, _, _ in image:neigh9(r, c) do
+			index = index * 2 + v
+		end
+		newimage:set(r, c, enhancer[index + 1])
+	end
+	return newimage
+end
+
+local function pprint(c)
+	if c == 0
+	then return "."
+	else return "#"
+	end
+end
+
+for i = 1, 50 do
+	image = enhance(image, enhancer)
+end
+
+local counter = 0
+for v in image:iter() do
+	counter = counter + v
+end
+print(counter)