From 4ccdd4610da674e68002eb95f21891cd3dea9e62 Mon Sep 17 00:00:00 2001
From: Jordan Doyle <jordan@doyle.la>
Date: Wed, 25 Dec 2024 14:18:40 +0700
Subject: [PATCH] Add 2024 day 13

---
 Cargo.lock |  9 ++++++++-
 Cargo.toml |  5 +++++
 README     |  4 ++--
 2024/13.rs | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 113 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index fbe92ee..174e56a 100644
--- a/Cargo.lock
+++ a/Cargo.lock
@@ -1,11 +1,18 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
+name = "anyhow"
+version = "1.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"
+
+[[package]]
 name = "aoc2023"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "arrayvec",
  "itertools",
  "nom",
diff --git a/Cargo.toml b/Cargo.toml
index 254d04e..2867d65 100644
--- a/Cargo.toml
+++ a/Cargo.toml
@@ -1,9 +1,10 @@
 [package]
 name = "aoc2023"
 version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+anyhow = "1"
 arrayvec = "0.7"
 rangemap = "1.4"
 strum = { version = "0.25", features = ["derive"] }
@@ -41,6 +42,10 @@
 [[bin]]
 name = "aoc2024-08"
 path = "2024/08.rs"
+
+[[bin]]
+name = "aoc2024-13"
+path = "2024/13.rs"
 
 [profile.release]
 overflow-checks = true
diff --git a/README b/README
index 68097cf..8f51829 100644
--- a/README
+++ a/README
@@ -26,8 +26,8 @@
 |       10 | OCaml    | |       10 | Haskell  |
 |       11 | OCaml    | |       11 | Haskell  |
 |       12 | OCaml    | |       12 | Rust     |
-+---------------------+ |       13 | Haskell  |
-                        |       14 | Haskell  |
+|       13 | Rust     | |       13 | Haskell  |
++---------------------+ |       14 | Haskell  |
                         |       15 | Haskell  |
                         |       16 | Haskell  |
                         |       17 | Rust     |
diff --git a/2024/13.rs b/2024/13.rs
new file mode 100755
index 0000000..57d472d 100755
--- /dev/null
+++ a/2024/13.rs
@@ -1,0 +1,98 @@
+use std::io::Read;
+
+use nom::{
+    bytes::complete::tag,
+    character::complete::{alpha1, digit1},
+    combinator::map_parser,
+    multi::separated_list1,
+    sequence::{preceded, terminated},
+    IResult,
+};
+
+fn main() -> Result<(), anyhow::Error> {
+    let mut input = String::new();
+    std::io::stdin().read_to_string(&mut input)?;
+
+    let (rest, input) = parse_input(&input).unwrap();
+    assert!(rest.is_empty());
+
+    part1(&input);
+    part2(&input);
+
+    Ok(())
+}
+
+fn solve(input: &Input) -> i64 {
+    let b = (input.prize.y * input.buttons[0].x - input.prize.x * input.buttons[0].y)
+        / (input.buttons[1].y * input.buttons[0].x - input.buttons[1].x * input.buttons[0].y);
+    let a = (input.prize.x - b * input.buttons[1].x) / input.buttons[0].x;
+
+    if input.buttons[0].x * a + input.buttons[1].x * b == input.prize.x
+        && input.buttons[0].y * a + input.buttons[1].y * b == input.prize.y
+    {
+        3 * a + b
+    } else {
+        0
+    }
+}
+
+fn part1(input: &[Input]) {
+    eprintln!("{}", input.iter().map(solve).sum::<i64>());
+}
+
+fn part2(input: &[Input]) {
+    eprintln!(
+        "{}",
+        input
+            .iter()
+            .cloned()
+            .map(|v| Input {
+                prize: Coords {
+                    x: v.prize.x + 10_000_000_000_000,
+                    y: v.prize.y + 10_000_000_000_000,
+                },
+                ..v
+            })
+            .map(|v| solve(&v))
+            .sum::<i64>()
+    );
+}
+
+#[derive(Debug, Copy, Clone)]
+pub struct Coords {
+    x: i64,
+    y: i64,
+}
+
+#[derive(Debug, Clone)]
+pub struct Input {
+    buttons: Vec<Coords>,
+    prize: Coords,
+}
+
+fn parse_i64(s: &str) -> IResult<&str, i64> {
+    map_parser(digit1, nom::character::complete::i64)(s)
+}
+
+fn parse_button(s: &str) -> IResult<&str, Coords> {
+    let (s, _b) = preceded(tag("Button "), alpha1)(s)?;
+    let (s, x) = preceded(tag(": X+"), parse_i64)(s)?;
+    let (s, y) = preceded(tag(", Y+"), parse_i64)(s)?;
+    Ok((s, Coords { x, y }))
+}
+
+fn parse_prize(s: &str) -> IResult<&str, Coords> {
+    let (s, x) = preceded(tag("Prize: X="), parse_i64)(s)?;
+    let (s, y) = preceded(tag(", Y="), parse_i64)(s)?;
+    Ok((s, Coords { x, y }))
+}
+
+fn parse_block(s: &str) -> IResult<&str, Input> {
+    let (s, buttons) = terminated(separated_list1(tag("\n"), parse_button), tag("\n"))(s)?;
+    let (s, prize) = terminated(parse_prize, tag("\n"))(s)?;
+    Ok((s, Input { buttons, prize }))
+}
+
+fn parse_input<'a>(s: &'a str) -> IResult<&'a str, Vec<Input>> {
+    separated_list1(tag("\n"), parse_block)(s)
+}
--
rgit 0.1.5