From 6ef26926ad9d78a236346db76dc9055ee0423252 Mon Sep 17 00:00:00 2001
From: Felix Van der Jeugt <felix.vanderjeugt@posteo.net>
Date: Wed, 22 Dec 2021 12:48:13 +0100
Subject: [PATCH] day 22 part 2 out of memory

---
 day22/part2.lua | 95 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100755 day22/part2.lua

diff --git a/day22/part2.lua b/day22/part2.lua
new file mode 100755
index 0000000..62cd4ce
--- /dev/null
+++ b/day22/part2.lua
@@ -0,0 +1,95 @@
+#!/usr/bin/env luajit
+require("utils")
+
+local function r(s, e)
+	-- Upper borders are exclusive here!
+	return { s=s, e=e }
+end
+
+local ranges = {}
+for line in io.lines(arg[3]) do
+	local b, x0, x1, y0, y1, z0, z1 = line:match("(.*) x=(.*)%.%.(.*),y=(.*)%.%.(.*),z=(.*)%.%.(.*)")
+	if b == "on" then b = true else b = false end
+	table.insert(ranges, {
+		b=b,
+		x=r(tonumber(x0), tonumber(x1) + 1),
+		y=r(tonumber(y0), tonumber(y1) + 1),
+		z=r(tonumber(z0), tonumber(z1) + 1),
+	})
+end
+
+
+local function intersect1d(a, b)
+	if a.e <= b.s or b.e <= a.s then
+		-- aaa   bbb
+		-- bbb   aaa
+		return { a }, {}, { b }
+	elseif a.s <= b.s and b.s <= a.e and a.e <= b.e then
+		-- aaa222bbb
+		return { r(a.s, b.s) }, { r(b.s, a.e) }, { r(a.e, b.e) }
+	elseif a.s <= b.s and b.e <= a.e then
+		-- aaa222aaa
+		return { r(a.s, b.s), r(b.e, a.e) }, { b }, {}
+	elseif b.s <= a.s and a.e <= b.e then
+		-- bbb222bbb
+		return {}, { a }, { r(b.s, a.s), r(a.e, b.e) }
+	elseif b.s <= a.s and b.e <= a.e then
+		-- bbb222aaa
+		return { r(b.e, a.e) }, { r(a.s, b.e) }, { r(b.s, a.s) }
+	else
+		error("unreachable?")
+	end
+end
+
+local function cut3d(a, b)
+	local aparts = {}
+	local xas, xabs, xbs = intersect1d(a.x, b.x)
+	local yas, yabs, ybs = intersect1d(a.y, b.y)
+	local zas, zabs, zbs = intersect1d(a.z, b.z)
+
+	local nobscombos = { { xas, yas, zas }
+	                   , { xas, yas, zabs }
+	                   , { xas, yabs, zas }
+	                   , { xas, yabs, zabs }
+	                   , { xabs, yas, zas }
+	                   , { xabs, yas, zabs }
+	                   , { xabs, yabs, zas }
+	                   }
+	for _, combo in pairs(nobscombos) do
+		local xs, ys, zs = unpack(combo)
+		for _, x in pairs(xs) do
+		for _, y in pairs(ys) do
+		for _, z in pairs(zs) do
+			table.insert(aparts, { b = a.b, x=x, y=y, z=z })
+		end
+		end
+		end
+	end
+
+	return aparts
+end
+
+local fixed = { ranges[1] }
+table.remove(ranges, 1)
+for _, range in pairs(ranges) do
+	local newfixed = {}
+	--printtable(range)
+	if range.b then
+		table.insert(newfixed, range)
+	end
+	for _, f in pairs(fixed) do
+		for _, fpart in pairs(cut3d(f, range)) do
+			--io.write(" ")
+			--printtable(fpart)
+			table.insert(newfixed, fpart)
+		end
+	end
+	fixed = newfixed
+end
+
+local count = 0
+for _, r in pairs(fixed) do
+	-- printtable(r)
+	count = count + (r.x.e - r.x.s)*(r.y.e - r.y.s)*(r.z.e - r.z.s)
+end
+io.write(string.format("%d\n", count))