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#![allow(dead_code)]
#![allow(unused_variables)]
use crate::prelude::*;
#[derive(Debug)]
enum Direction {
Up,
Down,
Left,
Right,
}
impl std::str::FromStr for Direction {
type Err = ();
fn from_str(s: &str) -> Result<Self, Self::Err> {
Ok(match s {
"U" => Self::Up,
"D" => Self::Down,
"L" => Self::Left,
"R" => Self::Right,
_ => return Err(()),
})
}
}
#[derive(Debug)]
pub struct Move {
dir: Direction,
count: usize,
}
impl Move {
fn parse(line: &str) -> Self {
let mut parts = line.split_whitespace();
let dir = parts.next().unwrap().parse().unwrap();
let count = parts.next().unwrap().parse().unwrap();
Self { dir, count }
}
}
pub struct Rope {
knots: Vec<(Row, Col)>,
}
impl Rope {
pub fn new(len: usize) -> Self {
Self {
knots: vec![Default::default(); len],
}
}
pub fn at(&self, pos: (Row, Col)) -> Option<usize> {
for (i, knot) in self.knots.iter().enumerate() {
if knot == &pos {
return Some(i);
}
}
None
}
}
pub struct Map {
grid: std::collections::VecDeque<std::collections::VecDeque<bool>>,
size: (Row, Col),
rope: Rope,
}
impl std::fmt::Debug for Map {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
writeln!(f, "({}, {})", self.size.0 .0, self.size.1 .0)?;
for row in (0..self.size.0 .0).rev() {
for col in 0..self.size.1 .0 {
write!(
f,
"{}",
if let Some(idx) = self.rope.at((Row(row), Col(col))) {
char::from(b'0' + u8::try_from(idx).unwrap())
} else if self.grid[row][col] {
'#'
} else {
'.'
}
)?;
}
writeln!(f)?;
}
Ok(())
}
}
impl Map {
fn new(len: usize) -> Self {
let mut grid = std::collections::VecDeque::new();
grid.push_back(std::collections::VecDeque::new());
grid[0].push_back(true);
Self {
grid,
size: (Row(1), Col(1)),
rope: Rope::new(len),
}
}
fn mv(&mut self, mv: &Move) {
// println!("{:?}", mv);
for _ in 0..mv.count {
self.step(&mv.dir);
}
}
fn step(&mut self, dir: &Direction) {
let (Row(row), Col(col)) = self.rope.knots[0];
match dir {
Direction::Up => {
if row == self.size.0 .0 - 1 {
let mut row_contents = std::collections::VecDeque::new();
row_contents
.resize_with(self.size.1 .0, Default::default);
self.grid.push_back(row_contents);
self.size.0 = Row(self.size.0 .0 + 1);
}
self.rope.knots[0].0 = Row(self.rope.knots[0].0 .0 + 1);
}
Direction::Down => {
if row == 0 {
let mut row_contents = std::collections::VecDeque::new();
row_contents
.resize_with(self.size.1 .0, Default::default);
self.grid.push_front(row_contents);
for knot in &mut self.rope.knots {
knot.0 = Row(knot.0 .0 + 1);
}
self.size.0 = Row(self.size.0 .0 + 1);
}
self.rope.knots[0].0 = Row(self.rope.knots[0].0 .0 - 1);
}
Direction::Left => {
if col == 0 {
for i in 0..self.size.0 .0 {
self.grid[i].push_front(Default::default());
}
for knot in &mut self.rope.knots {
knot.1 = Col(knot.1 .0 + 1);
}
self.size.1 = Col(self.size.1 .0 + 1);
}
self.rope.knots[0].1 = Col(self.rope.knots[0].1 .0 - 1);
}
Direction::Right => {
if col == self.size.1 .0 - 1 {
for i in 0..self.size.0 .0 {
self.grid[i].push_back(Default::default());
}
self.size.1 = Col(self.size.1 .0 + 1);
}
self.rope.knots[0].1 = Col(self.rope.knots[0].1 .0 + 1);
}
}
for i in 0..(self.rope.knots.len() - 1) {
if self.rope.knots[i + 1]
.0
.0
.abs_diff(self.rope.knots[i].0 .0)
> 1
|| self.rope.knots[i + 1]
.1
.0
.abs_diff(self.rope.knots[i].1 .0)
> 1
{
if self.rope.knots[i + 1].0 .0 < self.rope.knots[i].0 .0 {
self.rope.knots[i + 1].0 .0 += 1;
}
if self.rope.knots[i + 1].0 .0 > self.rope.knots[i].0 .0 {
self.rope.knots[i + 1].0 .0 -= 1;
}
if self.rope.knots[i + 1].1 .0 < self.rope.knots[i].1 .0 {
self.rope.knots[i + 1].1 .0 += 1;
}
if self.rope.knots[i + 1].1 .0 > self.rope.knots[i].1 .0 {
self.rope.knots[i + 1].1 .0 -= 1;
}
}
}
self.grid[self.rope.knots.last().unwrap().0 .0]
[self.rope.knots.last().unwrap().1 .0] = true;
}
}
pub fn parse(fh: File) -> Result<impl Iterator<Item = Move>> {
Ok(parse::lines(fh).map(|line| Move::parse(&line)))
}
pub fn part1(moves: impl Iterator<Item = Move>) -> Result<i64> {
let mut map = Map::new(2);
for mv in moves {
// println!("{:?}", map);
map.mv(&mv);
}
// println!("{:?}", map);
Ok(map
.grid
.iter()
.flat_map(|row| row.iter().copied())
.filter(|cell| *cell)
.count()
.try_into()
.unwrap())
}
pub fn part2(moves: impl Iterator<Item = Move>) -> Result<i64> {
let mut map = Map::new(10);
for mv in moves {
// println!("{:?}", map);
map.mv(&mv);
}
// println!("{:?}", map);
Ok(map
.grid
.iter()
.flat_map(|row| row.iter().copied())
.filter(|cell| *cell)
.count()
.try_into()
.unwrap())
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2022, 9).unwrap()).unwrap()).unwrap(),
6037
);
assert_eq!(
part2(parse(parse::data(2022, 9).unwrap()).unwrap()).unwrap(),
2485
);
}
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