day 10

day10/part1.lua

@@ -0,0 +1,35 @@
+#!/usr/bin/env luajit
+require("deque")
+require("utils")
+
+opening = {
+	["["] = "]",
+	["{"] = "}",
+	["<"] = ">",
+	["("] = ")",
+}
+
+score = {
+	["]"] = 57,
+	["}"] = 1197,
+	[">"] = 25137,
+	[")"] = 3,
+}
+
+local sum = 0
+
+for line in io.lines(arg[3]) do
+	d = deque()
+	for c in chars(line) do
+		if opening[c] then
+			d:append(opening[c])
+		else
+			if c ~= d:pop() then
+				sum = sum + score[c]
+				break
+			end
+		end
+	end
+end
+
+print(sum)

day10/part2.lua

@@ -0,0 +1,43 @@
+#!/usr/bin/env luajit
+require("deque")
+require("utils")
+
+opening = {
+	["["] = "]",
+	["{"] = "}",
+	["<"] = ">",
+	["("] = ")",
+}
+
+score = {
+	["]"] = 2,
+	["}"] = 3,
+	[">"] = 4,
+	[")"] = 1,
+}
+
+local scores = {}
+
+for line in io.lines(arg[3]) do
+	d = deque()
+	for c in chars(line) do
+		if opening[c] then
+			d:append(opening[c])
+		else
+			if c ~= d:pop() then
+				d = deque()
+				break
+			end
+		end
+	end
+	local linescore = 0
+	while d.size > 0 do
+		linescore = linescore * 5 + score[d:pop()]
+	end
+	if linescore ~= 0 then
+		table.insert(scores, linescore)
+	end
+end
+
+table.sort(scores)
+print(scores[(#scores + 1) / 2])