add 2024/day13

2024/13/main.py

@@ -0,0 +1,71 @@
+#!/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
+
+# algorithm stolen from:
+# https://www.reddit.com/r/adventofcode/comments/1hd7irq/2024_day_13_an_explanation_of_the_mathematics/
+
+import re
+
+
+def readinput():
+    with open("input", "r", encoding="utf-8") as file:
+        lines = file.read()
+        entries = lines.strip().split("\n\n")
+
+        games = []
+        for entry in entries:
+            regex = r"Button A: X(.*), Y+(.*)\nButton B: X+(.*), Y+(.*)\nPrize: X=(.*), Y=(.*)"
+            match = re.match(regex, "".join(entry))
+            games.append(
+                {
+                    "A": (int(match.group(1)), int(match.group(2))),
+                    "B": (int(match.group(3)), int(match.group(4))),
+                    "Prize": (int(match.group(5)), int(match.group(6))),
+                }
+            )
+
+    return games
+
+
+def min_tokens_for_game(game) -> int:
+    # pylint: disable=invalid-name
+    AX, AY = game["A"]
+    BX, BY = game["B"]
+    PrizeX, PrizeY = game["Prize"]
+
+    PressA = (PrizeX * BY - PrizeY * BX) / (AX * BY - AY * BX)
+    PressB = (PrizeY * AX - PrizeX * AY) / (AX * BY - AY * BX)
+
+    if not (PressA == int(PressA) and PressB == int(PressB)):
+        return 0
+
+    return (PressA * 3) + PressB
+
+
+def main():
+    games = readinput()
+
+    # part 1
+    tokens = 0
+    for game in games:
+        tokens += min_tokens_for_game(game)
+    print("Tokens required (Part 1): %d" % tokens)
+
+    # part 2
+    tokens = 0
+    for game in games:
+        game["Prize"] = (
+            game["Prize"][0] + 10000000000000,
+            game["Prize"][1] + 10000000000000,
+        )
+        tokens += min_tokens_for_game(game)
+    print("Tokens required (Part 2): %d" % tokens)
+
+
+if __name__ == "__main__":
+    main()