From 51f2e7a4fd0aa7b3d4bd0358d78104024db9e95c Mon Sep 17 00:00:00 2001
From: Sebastian Mark <smark@posteo.net>
Date: Mon, 9 Dec 2024 21:45:58 +0100
Subject: [PATCH] add 2023/day3.1

---
 2023/03/main.py | 69 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 2023/03/main.py

diff --git a/2023/03/main.py b/2023/03/main.py
new file mode 100644
index 0000000..a3a8c83
--- /dev/null
+++ b/2023/03/main.py
@@ -0,0 +1,69 @@
+#!/usr/bin/env python
+# -*- encoding: utf-8; py-indent-offset: 4 -*-
+
+# Author: Sebastian Mark
+# CC-BY-SA (https://creativecommons.org/licenses/by-sa/4.0/deed.de)
+
+# pylint: disable=missing-module-docstring,missing-function-docstring,consider-using-f-string
+
+import re
+
+
+def readinput():
+    with open("input", "r", encoding="utf-8") as file:
+        lines = [line.rstrip("\n") for line in file.readlines()]
+    return lines
+
+
+def find_numbers(lines: list) -> set:
+    # create a set of [(y,x,number),(y,x,number)]
+    numbers = set()
+    for y, line in enumerate(lines):
+        matches = re.finditer(r"\d+", line)
+        for match in matches:
+            x = match.start()
+            numbers.add((y, x, match.group()))
+    return numbers
+
+
+def check_partnumber(lines: list, starty: int, startx: int, partnumber: str) -> bool:
+    directions = [
+        (-1, 0),  # Up
+        (-1, 1),  # Up-right
+        (0, 1),  # Right
+        (1, 1),  # Down-right
+        (1, 0),  # Down
+        (1, -1),  # Down-left
+        (0, -1),  # Left
+        (-1, -1),  # Up-left
+    ]
+
+    width = len(lines[0])
+    height = len(lines)
+
+    for charpos in range(
+        startx, startx + len(partnumber)
+    ):  # for all numbers in the partnumber
+        for dy, dx in directions:  # check all directions
+            nxty, nxtx = starty + dy, charpos + dx  # new checkposition
+            if 0 <= nxtx < width and 0 <= nxty < height:  # validate borders
+                if lines[nxty][nxtx] not in "0123456789.":
+                    return True  # found symbol, this is a valid partnumber
+
+    return False
+
+
+def main():
+    lines = readinput()
+    numbers = find_numbers(lines)
+
+    # part 1
+    count = 0
+    for y, x, number in numbers:
+        if check_partnumber(lines, y, x, number):
+            count += int(number)
+    print("Sum of partnumbers: %d" % count)
+
+
+if __name__ == "__main__":
+    main()