From 67610d0808dac193166e4fc0d22f5504936c4efb Mon Sep 17 00:00:00 2001
From: Lars Martens <lars@martens.red>
Date: Fri, 13 Dec 2024 08:11:48 +0100
Subject: [PATCH] Solve 13.1

---
 src/bin/13.rs | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 src/bin/13.rs

diff --git a/src/bin/13.rs b/src/bin/13.rs
new file mode 100644
index 0000000..b804a61
--- /dev/null
+++ b/src/bin/13.rs
@@ -0,0 +1,105 @@
+use aoc::*;
+use cached::proc_macro::cached;
+use glam::U64Vec2;
+use itertools::Itertools;
+use regex::Regex;
+
+const INPUT: &str = include_str!("../../input/13");
+
+fn main() {
+    assert_example!(part1, "13-test", 480);
+    println!("Part 1: {}", part1(INPUT));
+    println!("Part 2: {}", part2(INPUT));
+}
+
+fn part1(input: &str) -> usize {
+    parse(input)
+        .into_iter()
+        .map(ClawMachine::tokens_to_win)
+        .sum()
+}
+
+fn part2(input: &str) -> usize {
+    parse(input)
+        .into_iter()
+        .map(ClawMachine::fix_conversion_error)
+        .map(ClawMachine::tokens_to_win2)
+        .sum()
+}
+
+fn parse(input: &str) -> Vec<ClawMachine> {
+    input.split("\n\n").map(ClawMachine::parse).collect_vec()
+}
+
+#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
+struct ClawMachine {
+    a: U64Vec2,
+    b: U64Vec2,
+    prize: U64Vec2,
+}
+
+impl ClawMachine {
+    fn fix_conversion_error(self) -> Self {
+        Self {
+            prize: U64Vec2::new(self.prize.x + 10000000000000, self.prize.y + 10000000000000),
+            ..self
+        }
+    }
+
+    fn tokens_to_win(self) -> usize {
+        tokens_to_win(self, 0, 0, U64Vec2::ZERO)
+    }
+
+    fn tokens_to_win2(self) -> usize {
+        tokens_to_win2(self, 0, 0, U64Vec2::ZERO)
+    }
+
+    fn parse(input: &str) -> Self {
+        let re =
+            Regex::new(r"X\+(\d+), Y\+(\d+)\n.*X\+(\d+), Y\+(\d+)\n.*X=(\d+), Y=(\d+)").unwrap();
+        let captures = re.captures(input).unwrap();
+        Self {
+            a: U64Vec2::new(captures[1].parse().unwrap(), captures[2].parse().unwrap()),
+            b: U64Vec2::new(captures[3].parse().unwrap(), captures[4].parse().unwrap()),
+            prize: U64Vec2::new(captures[5].parse().unwrap(), captures[6].parse().unwrap()),
+        }
+    }
+}
+
+#[cached]
+fn tokens_to_win(machine: ClawMachine, pressed_a: usize, pressed_b: usize, pos: U64Vec2) -> usize {
+    if pressed_a > 100 || pressed_b > 100 {
+        0
+    } else if pos == machine.prize {
+        pressed_a * 3 + pressed_b
+    } else if pos.x > machine.prize.x || pos.y > machine.prize.y {
+        0
+    } else {
+        let a = tokens_to_win(machine, pressed_a + 1, pressed_b, pos + machine.a);
+        let b = tokens_to_win(machine, pressed_a, pressed_b + 1, pos + machine.b);
+        match (a, b) {
+            (0, 0) => 0,
+            (a, 0) => a,
+            (0, b) => b,
+            (a, b) => a.min(b),
+        }
+    }
+}
+
+#[cached]
+fn tokens_to_win2(machine: ClawMachine, pressed_a: usize, pressed_b: usize, pos: U64Vec2) -> usize {
+    if pos == machine.prize {
+        pressed_a * 3 + pressed_b
+    } else if pos.x > machine.prize.x || pos.y > machine.prize.y {
+        0
+    } else {
+        let a = tokens_to_win(machine, pressed_a + 1, pressed_b, pos + machine.a);
+        let b = tokens_to_win(machine, pressed_a, pressed_b + 1, pos + machine.b);
+        match (a, b) {
+            (0, 0) => 0,
+            (a, 0) => a,
+            (0, b) => b,
+            (a, b) => a.min(b),
+        }
+    }
+}