2022 day14/rust: cleanup

2022/day14/rust/Cargo.toml

@@ -7,4 +7,4 @@ edition = "2021"
 
 [dependencies]
 aoc = { path = "../../../common/rust" }
-nom = "7.1.1"
+itertools = "0.10.5"

2022/day14/rust/src/main.rs

@@ -1,21 +1,20 @@
 #![warn(clippy::pedantic)]
 
-use std::{collections::BTreeSet, io::stdin};
+use std::{collections::HashSet, io::stdin};
 
 use aoc::vec2::{Line, Vec2};
-use nom::{
-    bytes::complete::tag, character::complete::i32, multi::separated_list1,
-    sequence::separated_pair, IResult, Parser,
-};
+use itertools::Itertools;
 
-fn parse_points(s: &str) -> IResult<&str, Vec<Vec2>, ()> {
-    separated_list1(
-        tag(" -> "),
-        separated_pair(i32, tag(","), i32).map(Vec2::from),
-    )(s)
+fn parse_points(s: &str) -> impl Iterator<Item = Vec2> + '_ {
+    s.split(" -> ").map(|p| {
+        let (x, y) = p.split_once(',').unwrap();
+        let x = x.parse().unwrap();
+        let y = y.parse().unwrap();
+        (x, y).into()
+    })
 }
 
-fn simulate(structures: BTreeSet<Vec2>, floor: Option<usize>) -> usize {
+fn simulate(structures: HashSet<Vec2>, floor: Option<usize>) -> usize {
     let mut points = structures;
     let lowest = points.iter().map(|v| v.y).max().unwrap();
     let start = Vec2::new(500, 0);
@@ -24,13 +23,13 @@ fn simulate(structures: BTreeSet<Vec2>, floor: Option<usize>) -> usize {
     'pieces: loop {
         let mut pos = start;
         'fall: loop {
-            let direction = [(0, 1), (-1, 1), (1, 1)]
+            let new_pos = [(0, 1), (-1, 1), (1, 1)]
                 .into_iter()
-                .map(Vec2::from)
-                .find(|&direction| !points.contains(&(pos + direction)));
+                .map(|direction| pos + direction.into())
+                .find(|pos| !points.contains(pos));
 
-            if let Some(direction) = direction {
-                pos += direction;
+            if let Some(new_pos) = new_pos {
+                pos = new_pos;
 
                 match floor {
                     Some(offset) => {
@@ -65,18 +64,16 @@ fn simulate(structures: BTreeSet<Vec2>, floor: Option<usize>) -> usize {
 }
 
 fn main() {
-    let lines = stdin().lines().flat_map(|line| {
-        parse_points(&line.unwrap())
-            .unwrap()
-            .1
-            .windows(2)
-            .map(|x| Line {
-                start: x[0],
-                end: x[1],
-            })
-            .collect::<Vec<_>>()
-    });
-    let points: BTreeSet<Vec2> = lines.flat_map(|line| line.points().unwrap()).collect();
+    let points: HashSet<Vec2> = stdin()
+        .lines()
+        .flat_map(|line| {
+            parse_points(&line.unwrap())
+                .tuple_windows()
+                .map(|(start, end)| Line { start, end })
+                .collect::<Vec<_>>()
+        })
+        .flat_map(|line| line.points().unwrap())
+        .collect();
 
     println!("{}", simulate(points.clone(), None));
     println!("{}", simulate(points, Some(2)));

Cargo.lock

@@ -598,7 +598,7 @@ name = "rust_2022_14"
 version = "0.1.0"
 dependencies = [
  "aoc",
- "nom",
+ "itertools",
 ]
 
 [[package]]