From d6f8ecf700e9a8a897ecad3616b9e79bc92ddbb4 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Sun, 4 Dec 2022 14:19:23 +0100
Subject: [PATCH] [py] Solve 2022_03

---
 py/aoc/__init__.py  |  3 ++-
 py/aoc/y2022/d03.py | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 py/aoc/y2022/d03.py

diff --git a/py/aoc/__init__.py b/py/aoc/__init__.py
index ed5f640..81bde3e 100644
--- a/py/aoc/__init__.py
+++ b/py/aoc/__init__.py
@@ -2,11 +2,12 @@ import sys
 import argparse
 from pathlib import Path
 
-from .y2022 import d01, d02, d04
+from .y2022 import d01, d02, d03, d04
 
 DAYS = {
     "2022_01": y2022.d01.solve,
     "2022_02": y2022.d02.solve,
+    "2022_03": y2022.d03.solve,
     "2022_04": y2022.d04.solve,
 }
 
diff --git a/py/aoc/y2022/d03.py b/py/aoc/y2022/d03.py
new file mode 100644
index 0000000..dd22bec
--- /dev/null
+++ b/py/aoc/y2022/d03.py
@@ -0,0 +1,23 @@
+def priority(item):
+    return ord(item.lower()) - ord("a") + 1 + item.isupper() * 26
+
+
+def chunks(things, n):
+    return (things[i : i + n] for i in range(0, len(things), n))
+
+
+def solve(inputstr):
+    rucksacks = inputstr.splitlines()
+
+    part1 = 0
+    for rucksack in rucksacks:
+        half = len(rucksack) // 2
+        common = set(rucksack[:half]) & set(rucksack[half:])
+        part1 += priority(common.pop())
+    print(f"Part 1: {part1}")
+
+    part2 = 0
+    for r1, r2, r3 in chunks(rucksacks, 3):
+        common = set(r1) & set(r2) & set(r3)
+        part2 += priority(common.pop())
+    print(f"Part 2: {part2}")