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-rw-r--r--2020/rust/Cargo.toml4
-rw-r--r--2020/rust/day11/Cargo.toml10
-rw-r--r--2020/rust/day11/src/main.rs345
3 files changed, 357 insertions, 2 deletions
diff --git a/2020/rust/Cargo.toml b/2020/rust/Cargo.toml
index a51672a..19751a7 100644
--- a/2020/rust/Cargo.toml
+++ b/2020/rust/Cargo.toml
@@ -10,8 +10,8 @@ members = [
"day07",
"day08",
"day09",
-# "day10",
-# "day11",
+ "day10",
+ "day11",
# "day12",
# "day13",
# "day14",
diff --git a/2020/rust/day11/Cargo.toml b/2020/rust/day11/Cargo.toml
new file mode 100644
index 0000000..00a1103
--- /dev/null
+++ b/2020/rust/day11/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "day11"
+version = "0.1.0"
+authors = ["cos <cos>"]
+edition = "2018"
+
+[dependencies]
+aoc = { path = "../aoc" }
+anyhow = "1.0"
+thiserror = "1.0"
diff --git a/2020/rust/day11/src/main.rs b/2020/rust/day11/src/main.rs
new file mode 100644
index 0000000..014caed
--- /dev/null
+++ b/2020/rust/day11/src/main.rs
@@ -0,0 +1,345 @@
+use anyhow::{Result, anyhow};
+use std::env::args;
+use std::fmt;
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+use std::ops::AddAssign;
+use std::path::Path;
+use thiserror::Error;
+
+#[derive(Clone, Copy)]
+struct CoordPair {
+ x: isize,
+ y: isize,
+}
+
+impl AddAssign for CoordPair {
+ fn add_assign(&mut self, other: Self) {
+ *self = Self {
+ x: self.x + other.x,
+ y: self.y + other.y,
+ };
+ }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+enum SeatState {
+ Floor,
+ Empty,
+ Occupied,
+}
+
+#[derive(Error, Debug)]
+pub enum SeatStateError {
+ #[error("Could not access SeatState")]
+ Invalid,
+}
+
+#[derive(PartialEq)]
+struct WaitingArea {
+ width: isize,
+ height: isize,
+ grid: Vec<SeatState>,
+}
+
+#[derive(Error, Debug)]
+pub enum WaitingAreaError {
+ #[error("Could not access WaitingArea")]
+ Invalid,
+}
+
+impl WaitingArea {
+ fn get_seat_state(&self, pos: CoordPair) -> Option<SeatState> {
+ self.grid.get((pos.y * self.width + pos.x) as usize).copied()
+ }
+
+ fn set_seat_state(&mut self, pos: CoordPair, state: SeatState) {
+ let entry = self.grid.get_mut((pos.y * self.width + pos.x) as usize).unwrap();
+ *entry = state;
+ }
+
+ fn count_neighbours(&self, pos: CoordPair) -> isize {
+ let mut neighbours = 0;
+
+ let x_start = match (pos.x as isize)-1 {
+ n if n < 0 => 0,
+ n => n as isize,
+ };
+ let y_start = match (pos.y as isize)-1 {
+ n if n < 0 => 0,
+ n => n as isize,
+ };
+ let x_end = match pos.x+1 {
+ n if n > self.width-1 => self.width-1,
+ n => n,
+ };
+ let y_end = match pos.y+1 {
+ n if n > self.height-1 => self.height-1,
+ n => n,
+ };
+
+ for y in y_start..=y_end {
+ for x in x_start..=x_end {
+ if x == pos.x && y == pos.y {
+ continue;
+ }
+ match self.get_seat_state(CoordPair {x, y}) {
+ Some(SeatState::Occupied) => neighbours += 1,
+ _ => { },
+ }
+ }
+ }
+
+ neighbours
+ }
+
+ fn count_visible(&self, pos: CoordPair) -> isize {
+ let slopes = vec![
+ CoordPair { x: 1, y: 0, },
+ CoordPair { x: 1, y: 1, },
+ CoordPair { x: 0, y: 1, },
+ CoordPair { x: -1, y: 1, },
+ CoordPair { x: -1, y: 0, },
+ CoordPair { x: -1, y: -1, },
+ CoordPair { x: 0, y: -1, },
+ CoordPair { x: 1, y: -1, },
+ ];
+
+ let visible_occupied = slopes.iter().map(|slope| {
+ let mut check_pos = CoordPair { x: pos.x, y: pos.y, };
+ check_pos += *slope;
+ while check_pos.x < self.width && check_pos.y < self.height &&
+ check_pos.x >= 0 && check_pos.y >= 0
+ {
+ match self.get_seat_state(check_pos) {
+ Some(SeatState::Occupied) => return 1,
+ Some(SeatState::Floor) => {},
+ _ => return 0,
+ }
+ check_pos += *slope;
+ }
+
+ 0
+ }).sum();
+
+ visible_occupied
+ }
+
+ fn clone(&self) -> WaitingArea {
+ let mut grid = vec![];
+
+ for y in 0..self.height {
+ for x in 0..self.width {
+ match self.get_seat_state(CoordPair {x, y}) {
+ Some(SeatState::Floor) => grid.push(SeatState::Floor),
+ Some(SeatState::Empty) => grid.push(SeatState::Empty),
+ Some(SeatState::Occupied) => grid.push(SeatState::Occupied),
+ None => panic!("You've been eaten by a grue"),
+ };
+ }
+ }
+
+ WaitingArea {
+ height: self.height,
+ width: self.width,
+ grid,
+ }
+ }
+
+ fn apply_rules(&self) -> WaitingArea {
+ let mut grid = vec![];
+
+ for y in 0..self.height {
+ for x in 0..self.width {
+ match self.get_seat_state(CoordPair {x, y}) {
+ Some(SeatState::Floor) => grid.push(SeatState::Floor),
+ Some(SeatState::Empty) => {
+ if self.count_neighbours(CoordPair {x, y}) > 0 {
+ grid.push(SeatState::Empty);
+ } else {
+ grid.push(SeatState::Occupied);
+ }
+ },
+ Some(SeatState::Occupied) => if self.count_neighbours(CoordPair {x, y}) >= 4 {
+ grid.push(SeatState::Empty);
+ } else {
+ grid.push(SeatState::Occupied);
+ },
+ None => panic!("You've been eaten by a grue"),
+ };
+ }
+ }
+
+ WaitingArea {
+ height: self.height,
+ width: self.width,
+ grid,
+ }
+ }
+
+ fn apply_new_rules(&self) -> WaitingArea {
+ let mut grid = vec![];
+
+ for y in 0..self.height {
+ for x in 0..self.width {
+ match self.get_seat_state(CoordPair {x, y}) {
+ Some(SeatState::Floor) => grid.push(SeatState::Floor),
+ Some(SeatState::Empty) => {
+ if self.count_visible(CoordPair {x, y}) > 0 {
+ grid.push(SeatState::Empty);
+ } else {
+ grid.push(SeatState::Occupied);
+ }
+ },
+ Some(SeatState::Occupied) => if self.count_visible(CoordPair {x, y}) >= 5 {
+ grid.push(SeatState::Empty);
+ } else {
+ grid.push(SeatState::Occupied);
+ },
+ None => panic!("You've been eaten by a grue"),
+ };
+ }
+ }
+
+ WaitingArea {
+ height: self.height,
+ width: self.width,
+ grid,
+ }
+ }
+
+ fn count_seats(&self) -> (isize, isize, isize ) {
+ let ( mut empty, mut occupied, mut floor ) = ( 0, 0, 0 );
+
+ for y in 0..self.height {
+ for x in 0..self.width {
+ match self.get_seat_state(CoordPair {x, y}) {
+ Some(SeatState::Floor) => floor += 1,
+ Some(SeatState::Empty) => empty += 1,
+ Some(SeatState::Occupied) => occupied += 1,
+ None => panic!("You've been eaten by a grue"),
+ };
+ }
+ }
+
+ ( empty, occupied, floor )
+ }
+}
+
+impl fmt::Debug for WaitingArea {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ writeln!(f, "WaitingArea: [")?;
+ for y in 0..self.height {
+ for x in 0..self.width {
+ match self.get_seat_state(CoordPair {x, y}) {
+ Some(SeatState::Floor) => write!(f, "."),
+ Some(SeatState::Empty) => write!(f, "L"),
+ Some(SeatState::Occupied) => write!(f, "#"),
+ None => write!(f, "You've been eaten by a grue"),
+ }?;
+ }
+ writeln!(f)?;
+ }
+
+ f.write_str("] ")
+ }
+}
+
+
+fn read_input<T: AsRef<Path>>(filename: T) -> Result<WaitingArea> {
+ let f = File::open(filename)?;
+ let reader = BufReader::new(f);
+
+ let waiting_area = reader.lines()
+ .fold(Ok(WaitingArea { width: 0, height: 0, grid: vec![] }), |acc, l| {
+ let line = l?;
+ let row: Result<Vec<SeatState>> = line.chars().map(|c| match c {
+ 'L' => Ok(SeatState::Empty),
+ '.' => Ok(SeatState::Floor),
+ '#' => Ok(SeatState::Occupied),
+ _ => Err(anyhow!("Invalid map character: '{}'", c)),
+ }).collect();
+
+ match acc {
+ Ok(mut a) => {
+ a.grid.append(&mut row?);
+ a.height += 1;
+ Ok(a)
+ },
+ Err(err) => Err(err)
+ }
+ });
+ match waiting_area {
+ Ok(mut wa) => {
+ wa.width = wa.grid.len() as isize/wa.height;
+ Ok(wa)
+ },
+ err => err,
+ }
+}
+
+fn part1(input: &WaitingArea) -> Result<isize> {
+ let mut waiting_area = input.clone();
+ loop {
+ let next = waiting_area.apply_rules();
+
+ if next == waiting_area {
+ break;
+ }
+ waiting_area = next;
+ }
+
+ let ( _empty, occupied, _floor ) = waiting_area.count_seats();
+ Ok(occupied)
+}
+
+fn part2(input: &WaitingArea) -> Result<isize> {
+ let mut waiting_area = input.clone();
+ loop {
+ let next = waiting_area.apply_new_rules();
+
+ if next == waiting_area {
+ break;
+ }
+ waiting_area = next;
+ }
+
+ let ( _empty, occupied, _floor ) = waiting_area.count_seats();
+ Ok(occupied)
+}
+
+fn main() {
+ let ( do_part_1, do_part_2 ) = aoc::do_parts();
+
+ let filename = match args().nth(1) {
+ Some(f) => f,
+ None => {
+ eprintln!("Missing input filename");
+ std::process::exit(1);
+ },
+ };
+ match read_input(filename) {
+ Ok(input) => {
+ if do_part_1 {
+ match part1(&input) {
+ Ok(solution) => println!("Part1: {}", solution),
+ Err(err) => {
+ eprintln!("Part1, no solution found: {}", err);
+ std::process::exit(1);
+ }
+ };
+ }
+ if do_part_2 {
+ match part2(&input) {
+ Ok(solution) => println!("Part2: {}", solution),
+ Err(err) => {
+ eprintln!("Part2, no solution found: {}", err);
+ std::process::exit(1);
+ }
+ };
+ }
+ },
+ Err(err) => eprintln!("Could not read input: {}", err),
+ }
+}
+
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