From e126477ef5666cfebf49ae8416b11353fc4fea03 Mon Sep 17 00:00:00 2001
From: Thibaud <thibaud.gasser@gmx.com>
Date: Mon, 28 Jul 2025 13:40:33 +0200
Subject: [PATCH] 2018 day 3

---
 2018/day3/day3.py | 55 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 2018/day3/day3.py

diff --git a/2018/day3/day3.py b/2018/day3/day3.py
new file mode 100644
index 0000000..9989418
--- /dev/null
+++ b/2018/day3/day3.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+import re
+import itertools
+from dataclasses import dataclass
+from collections import defaultdict
+
+
+@dataclass
+class Rectangle:
+    x: int
+    y: int
+    width: int
+    height: int
+
+    @property
+    def x2(self):
+        return self.x + self.width
+
+    @property
+    def y2(self):
+        return self.y + self.height
+
+
+def parse_line(l):
+    parsed = re.findall(r"\d+", l)
+    id_, x, y, width, height = map(int, parsed)
+    return id_, Rectangle(x, y, width, height)
+
+
+def main(inp):
+    regions = defaultdict(set)
+    for id_, region in map(parse_line, inp):
+        for x in range(region.x, region.x2):
+            for y in range(region.y, region.y2):
+                regions[x, y].add(id_)
+
+    total = sum(len(x) > 1 for x in regions.values())
+    print(f"Part 1: ", total)
+
+    all_ids = set()
+    overlapping_ids = set()
+    for region in regions.values():
+        all_ids.update(region)
+        if len(region) > 1:
+            overlapping_ids.update(region)
+    difference = all_ids - overlapping_ids
+    print(f"Part 2: {difference.pop()}")
+
+    
+if __name__ == '__main__':
+    import sys
+    infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
+    with open(infile) as inp:
+        main([l.rstrip() for l in inp.readlines()])
+