2022 day13/rust: add solution

2022/day13/rust/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "rust_2022_13"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+aoc = { path = "../../../common/rust" }
+nom = "7.1.1"

2022/day13/rust/src/main.rs

@@ -0,0 +1,78 @@
+#![warn(clippy::pedantic)]
+
+use nom::Parser;
+use std::io::{stdin, Read};
+
+use nom::{
+    branch::alt, bytes::complete::tag, character::complete::u32, multi::separated_list0,
+    sequence::delimited, IResult,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+enum Data {
+    List(Vec<Data>),
+    Number(usize),
+}
+
+impl PartialOrd for Data {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Data {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        match (self, other) {
+            (Data::List(l), Data::List(r)) => l.as_slice().cmp(r),
+            (Data::List(l), r @ Data::Number(_)) => l.iter().cmp([r]),
+            (l @ Data::Number(_), Data::List(r)) => [l].into_iter().cmp(r.iter()),
+            (Data::Number(l), Data::Number(r)) => l.cmp(r),
+        }
+    }
+}
+
+fn parse_data(s: &str) -> IResult<&str, Data, ()> {
+    alt((
+        delimited(tag("["), separated_list0(tag(","), parse_data), tag("]")).map(Data::List),
+        u32.map(|i| Data::Number(usize::try_from(i).unwrap())),
+    ))(s)
+}
+
+fn main() {
+    let mut data = String::new();
+    stdin().read_to_string(&mut data).unwrap();
+
+    let pairs: Vec<_> = data
+        .split("\n\n")
+        .map(|pair| {
+            let (left, right) = pair.split_once('\n').unwrap();
+            (parse_data(left).unwrap().1, parse_data(right).unwrap().1)
+        })
+        .collect();
+
+    let sum: usize = pairs
+        .iter()
+        .enumerate()
+        .filter_map(|(i, (left, right))| (left <= right).then_some(i + 1))
+        .sum();
+
+    println!("{}", sum);
+
+    let mut sorted: Vec<_> = pairs
+        .into_iter()
+        .flat_map(|(left, right)| [left, right])
+        .collect();
+    let divider = |divider| Data::List(vec![Data::List(vec![Data::Number(divider)])]);
+    sorted.push(divider(2));
+    sorted.push(divider(6));
+    sorted.sort();
+
+    let index = |divider| {
+        sorted
+            .binary_search(&Data::List(vec![Data::List(vec![Data::Number(divider)])]))
+            .unwrap()
+            + 1
+    };
+
+    println!("{}", index(2) * index(6));
+}

Cargo.lock

@@ -585,6 +585,14 @@ dependencies = [
  "petgraph",
 ]
 
+[[package]]
+name = "rust_2022_13"
+version = "0.1.0"
+dependencies = [
+ "aoc",
+ "nom",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.11"

Cargo.toml

@@ -22,4 +22,5 @@ members = [
 	"2022/day10/rust",
 	"2022/day11/rust",
 	"2022/day12/rust",
+	"2022/day13/rust",
 ]