From 47eb33e373f0b6fe9891b786e8ba3951fc41476a Mon Sep 17 00:00:00 2001
From: Juan Marín Noguera <juan@mnpi.eu>
Date: Sun, 1 Dec 2024 14:29:18 +0100
Subject: Day 01

This also includes a template to call the relevant functions from each
day more conveniently.
---
 .gitignore | 43 ++-----------------------------------------
 01.lua     | 39 +++++++++++++++++++++++++++++++++++++++
 main       | 29 +++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+), 41 deletions(-)
 create mode 100644 01.lua
 create mode 100755 main

diff --git a/.gitignore b/.gitignore
index 6fd0a37..0a45c8d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,41 +1,2 @@
-# Compiled Lua sources
-luac.out
-
-# luarocks build files
-*.src.rock
-*.zip
-*.tar.gz
-
-# Object files
-*.o
-*.os
-*.ko
-*.obj
-*.elf
-
-# Precompiled Headers
-*.gch
-*.pch
-
-# Libraries
-*.lib
-*.a
-*.la
-*.lo
-*.def
-*.exp
-
-# Shared objects (inc. Windows DLLs)
-*.dll
-*.so
-*.so.*
-*.dylib
-
-# Executables
-*.exe
-*.out
-*.app
-*.i*86
-*.x86_64
-*.hex
-
+*~
+*.in
diff --git a/01.lua b/01.lua
new file mode 100644
index 0000000..fefffa4
--- /dev/null
+++ b/01.lua
@@ -0,0 +1,39 @@
+function lines ()
+    local x = io.read("*n")
+    local y = io.read("*n")
+    return x, y
+end
+
+local input = {{}, {}}
+
+for x, y in lines do
+    table.insert(input[1], x)
+    table.insert(input[2], y)
+end
+
+function input:part1()
+    table.sort(self[1])
+    table.sort(self[2])
+
+    local sum = 0
+    for i = 1,#self[1] do
+        sum = sum + math.abs(self[1][i] - self[2][i])
+    end
+
+    print(sum)
+end
+
+function input:part2()
+    local dict = {}
+    for _, val in ipairs(self[2]) do
+        dict[val] = (dict[val] or 0) + 1
+    end
+
+    local sum = 0
+    for _, val in ipairs(self[1]) do
+        if dict[val] then sum = sum + val * dict[val] end
+    end
+    print(sum)
+end
+
+return input
diff --git a/main b/main
new file mode 100755
index 0000000..38189ee
--- /dev/null
+++ b/main
@@ -0,0 +1,29 @@
+#!/usr/bin/lua
+
+if #arg < 1 or #arg > 2 then
+    error ("Syntax: %s <DAY><a|b> [inputfile]"):format(arg[0])
+    os.exit(1)
+end
+
+local num, letter = arg[1]:match("^(%d+)([ab])$")
+if not num then
+    error ('Expected <DAY><a|b> as first argument (e.g. "01b"), got: %s'):format(arg[1])
+    os.exit(1)
+end
+num = tonumber(num)
+
+local script = ("%02d.lua"):format(num)
+local infile = arg[2] or ("%02d.in"):format(num)
+local input_stream = io.open(infile)
+if input_stream then
+    io.input(input_stream)
+else
+    print "Reading from standard input."
+end
+
+local parsed = loadfile(script)()
+if letter == 'a' then
+    parsed:part1()
+else
+    parsed:part2()
+end
-- 
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