From c8ab67d1452d3762d2a542368c315f8841d18f34 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Fri, 13 Dec 2024 08:36:20 +0100
Subject: [PATCH] Implement 2024 day 13

---
 2024/src/aoc/days/day13.py | 43 ++++++++++++++++++++++++++++++++++++++
 2024/tests/samples/13.txt  | 15 +++++++++++++
 2024/tests/test_day13.py   |  7 +++++++
 3 files changed, 65 insertions(+)
 create mode 100644 2024/src/aoc/days/day13.py
 create mode 100644 2024/tests/samples/13.txt
 create mode 100644 2024/tests/test_day13.py

diff --git a/2024/src/aoc/days/day13.py b/2024/src/aoc/days/day13.py
new file mode 100644
index 0000000..c959c1e
--- /dev/null
+++ b/2024/src/aoc/days/day13.py
@@ -0,0 +1,43 @@
+import re
+
+import numpy
+
+from . import CombinedRunner
+
+NASTY_REGEX = r"""Button A: X\+(\d+), Y\+(\d+)
+Button B: X\+(\d+), Y\+(\d+)
+Prize: X=(\d+), Y=(\d+)"""
+
+
+class DayRunner(CombinedRunner):
+    @classmethod
+    def run_both(cls, input: str) -> tuple[int, int]:
+        machines = re.findall(NASTY_REGEX, input)
+
+        cost_to_win = 0
+        cost_to_win2 = 0
+        scale = 10000000000000
+
+        for machine in machines:
+            ax, ay, bx, by, px, py = map(int, machine)
+
+            X = numpy.array([[ax, bx], [ay, by]])
+            B = numpy.array([px, py])
+            B2 = numpy.array([px + scale, py + scale])
+
+            A = numpy.linalg.solve(X, B)
+            A2 = numpy.linalg.solve(X, B2)
+
+            a_press, b_press = map(round, A)
+            a_press2, b_press2 = map(round, A2)
+
+            if a_press * ax + b_press * bx == px and a_press * ay + b_press * by == py:
+                cost_to_win += 3 * a_press + b_press
+
+            if (
+                a_press2 * ax + b_press2 * bx == px + scale
+                and a_press2 * ay + b_press2 * by == py + scale
+            ):
+                cost_to_win2 += 3 * a_press2 + b_press2
+
+        return cost_to_win, cost_to_win2
diff --git a/2024/tests/samples/13.txt b/2024/tests/samples/13.txt
new file mode 100644
index 0000000..912f482
--- /dev/null
+++ b/2024/tests/samples/13.txt
@@ -0,0 +1,15 @@
+Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279
diff --git a/2024/tests/test_day13.py b/2024/tests/test_day13.py
new file mode 100644
index 0000000..fd3e433
--- /dev/null
+++ b/2024/tests/test_day13.py
@@ -0,0 +1,7 @@
+from aoc.days.day13 import DayRunner
+
+from . import get_data
+
+
+def test_sample_part1() -> None:
+    assert DayRunner.part1(get_data(13)) == 480