From 7896aafcd779f298102cd53ad5b9f72f77d7ef19 Mon Sep 17 00:00:00 2001
From: Xiretza <xiretza@xiretza.xyz>
Date: Fri, 9 Dec 2022 06:55:31 +0100
Subject: [PATCH] 2022 day9/rust: cleanup
---
2022/day9/rust/src/main.rs | 136 ++++++++++++-------------------------
common/rust/src/lib.rs | 1 +
common/rust/src/vec2.rs | 108 +++++++++++++++++++++++++++++
3 files changed, 152 insertions(+), 93 deletions(-)
create mode 100644 common/rust/src/vec2.rs
diff --git a/2022/day9/rust/src/main.rs b/2022/day9/rust/src/main.rs
index 151dc7a..e7f6551 100644
--- a/2022/day9/rust/src/main.rs
+++ b/2022/day9/rust/src/main.rs
@@ -3,113 +3,63 @@
use std::{
collections::BTreeSet,
io::{stdin, Read},
- ops::{Add, AddAssign, Sub},
};
-use aoc::*;
+use aoc::vec2::{Direction, Vec2};
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct Vec2 {
- x: i32, // increases toward right
- y: i32, // increases toward top
+fn tail_movement(following: Vec2, tail: Vec2) -> Vec2 {
+ let (dx, dy) = (following - tail).into();
+
+ let movement = if dx.abs() <= 1 && dy.abs() <= 1 {
+ (0, 0)
+ } else {
+ (dx.signum(), dy.signum())
+ };
+ movement.into()
}
-impl Vec2 {
- #[must_use]
- pub fn new(x: i32, y: i32) -> Self {
- Self { x, y }
- }
+fn simulate_knots(num_knots: usize, instructions: &[(Direction, usize)]) -> usize {
+ const START: Vec2 = Vec2::new(0, 0);
- #[must_use]
- pub fn map(self, mut f: impl FnMut(i32) -> i32) -> Self {
- Self {
- x: f(self.x),
- y: f(self.y),
+ assert!(num_knots >= 2);
+
+ let mut knots = vec![START; num_knots];
+ let mut tail_positions = BTreeSet::new();
+ tail_positions.insert(START);
+
+ for (direction, distance) in instructions {
+ for _i in 0..*distance {
+ knots[0] += Vec2::from(*direction);
+
+ let tail = knots
+ .iter_mut()
+ .reduce(|following, knot| {
+ *knot += tail_movement(*following, *knot);
+ knot
+ })
+ .unwrap();
+
+ tail_positions.insert(*tail);
}
}
-}
-impl Add for Vec2 {
- type Output = Self;
-
- fn add(self, rhs: Self) -> Self::Output {
- Self {
- x: self.x + rhs.x,
- y: self.y + rhs.y,
- }
- }
-}
-
-impl AddAssign for Vec2 {
- fn add_assign(&mut self, rhs: Self) {
- self.x += rhs.x;
- self.y += rhs.y;
- }
-}
-
-impl Sub for Vec2 {
- type Output = Self;
-
- fn sub(self, rhs: Self) -> Self::Output {
- Self {
- x: self.x - rhs.x,
- y: self.y - rhs.y,
- }
- }
-}
-
-impl From<(i32, i32)> for Vec2 {
- fn from((x, y): (i32, i32)) -> Self {
- Self { x, y }
- }
-}
-
-impl From<Vec2> for (i32, i32) {
- fn from(v: Vec2) -> Self {
- (v.x, v.y)
- }
-}
-
-fn get_direction_vec(direction: &str) -> Vec2 {
- match direction {
- "U" => (0, 1),
- "R" => (1, 0),
- "D" => (0, -1),
- "L" => (-1, 0),
- _ => panic!(),
- }
- .into()
+ tail_positions.len()
}
fn main() {
let mut data = String::new();
stdin().read_to_string(&mut data).unwrap();
- let mut knots = vec![Vec2::new(0, 0); 10];
+ let instructions: Vec<_> = data
+ .lines()
+ .map(|line| {
+ let (direction, distance) = line.split_once(' ').unwrap();
+ let direction = direction.parse().unwrap();
+ let distance = distance.parse().unwrap();
+ (direction, distance)
+ })
+ .collect();
- let mut tail_positions = BTreeSet::new();
- tail_positions.insert(*knots.last().unwrap());
-
- for line in data.lines() {
- let (direction, distance) = line.split_once(' ').unwrap();
- let distance: usize = distance.parse().unwrap();
-
- for _i in 0..distance {
- knots[0] += get_direction_vec(direction);
- let mut following = knots[0];
-
- for knot in &mut knots[1..] {
- let delta = match (following - *knot).into() {
- (x, y) if x.abs() <= 1 && y.abs() <= 1 => (0, 0),
- (x, y) => (x.signum(), y.signum()),
- }
- .into();
- *knot += delta;
- following = *knot;
- }
- tail_positions.insert(*knots.last().unwrap());
- }
- }
-
- println!("{:?}", tail_positions.len());
+ println!("{:?}", simulate_knots(2, &instructions));
+ println!("{:?}", simulate_knots(10, &instructions));
}
diff --git a/common/rust/src/lib.rs b/common/rust/src/lib.rs
index 8be2e20..c79c26f 100644
--- a/common/rust/src/lib.rs
+++ b/common/rust/src/lib.rs
@@ -1,6 +1,7 @@
#![warn(clippy::pedantic)]
mod section_range;
+pub mod vec2;
use std::{mem, path::Path};
diff --git a/common/rust/src/vec2.rs b/common/rust/src/vec2.rs
new file mode 100644
index 0000000..d05e710
--- /dev/null
+++ b/common/rust/src/vec2.rs
@@ -0,0 +1,108 @@
+use std::{
+ ops::{Add, AddAssign, Sub, SubAssign},
+ str::FromStr,
+};
+
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Vec2 {
+ x: i32, // increases toward right
+ y: i32, // increases toward top
+}
+
+impl Vec2 {
+ #[must_use]
+ pub const fn new(x: i32, y: i32) -> Self {
+ Self { x, y }
+ }
+
+ #[must_use]
+ pub fn map(self, mut f: impl FnMut(i32) -> i32) -> Self {
+ Self {
+ x: f(self.x),
+ y: f(self.y),
+ }
+ }
+}
+
+impl Add for Vec2 {
+ type Output = Self;
+
+ fn add(self, rhs: Self) -> Self::Output {
+ Self {
+ x: self.x + rhs.x,
+ y: self.y + rhs.y,
+ }
+ }
+}
+
+impl AddAssign for Vec2 {
+ fn add_assign(&mut self, rhs: Self) {
+ self.x += rhs.x;
+ self.y += rhs.y;
+ }
+}
+
+impl Sub for Vec2 {
+ type Output = Self;
+
+ fn sub(self, rhs: Self) -> Self::Output {
+ Self {
+ x: self.x - rhs.x,
+ y: self.y - rhs.y,
+ }
+ }
+}
+
+impl SubAssign for Vec2 {
+ fn sub_assign(&mut self, rhs: Self) {
+ self.x -= rhs.x;
+ self.y -= rhs.y;
+ }
+}
+
+impl From<(i32, i32)> for Vec2 {
+ fn from((x, y): (i32, i32)) -> Self {
+ Self { x, y }
+ }
+}
+
+impl From<Vec2> for (i32, i32) {
+ fn from(v: Vec2) -> Self {
+ (v.x, v.y)
+ }
+}
+
+impl From<Direction> for Vec2 {
+ /// Creates a unit vector in the given direction.
+ fn from(dir: Direction) -> Self {
+ match dir {
+ Direction::Up => (0, 1),
+ Direction::Down => (0, -1),
+ Direction::Left => (-1, 0),
+ Direction::Right => (1, 0),
+ }
+ .into()
+ }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Direction {
+ Up,
+ Down,
+ Left,
+ Right,
+}
+
+impl FromStr for Direction {
+ type Err = ();
+
+ fn from_str(s: &str) -> Result<Self, Self::Err> {
+ match s {
+ "U" => Ok(Direction::Up),
+ "D" => Ok(Direction::Down),
+ "L" => Ok(Direction::Left),
+ "R" => Ok(Direction::Right),
+ _ => Err(()),
+ }
+ }
+}