day 12 done
This commit is contained in:
Dylan Thies
201
day12/src/main.rs
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201
day12/src/main.rs
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#![warn(clippy::all, clippy::pedantic)]
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use std::{
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collections::VecDeque,
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fs::File,
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io::{prelude::*, BufReader},
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};
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pub type BoxError = std::boxed::Box<
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dyn std::error::Error // must implement Error to satisfy ?
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+ std::marker::Send // needed for threads
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+ std::marker::Sync, // needed for threads
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>;
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
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struct Square {
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pub height: u8,
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pub pos: (usize, usize),
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}
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impl Square {
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pub fn _index(&self, grid_size: &(usize, usize)) -> usize {
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grid_size.1 * self.pos.0 + self.pos.1
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}
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pub fn can_go_to(&self, other: &Self) -> bool {
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let from_height = self.height;
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let to_height = other.height;
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if from_height + 1 < to_height {
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return false;
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}
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let (from_row, from_col) = self.pos;
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let (to_row, to_col) = other.pos;
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(from_row == to_row || from_col == to_col)
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&& from_row + 1 >= to_row
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&& from_row <= to_row + 1
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&& from_col + 1 >= to_col
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&& from_col <= to_col + 1
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}
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}
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#[derive(Debug, Default, Clone)]
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struct Game {
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board: Vec<Square>,
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distances: Vec<Option<u64>>,
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board_size: (usize, usize),
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start_pos: (usize, usize),
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end_pos: (usize, usize),
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}
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impl From<File> for Game {
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fn from(file: File) -> Self {
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let buffer = BufReader::new(file);
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let mut board = Vec::new();
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let mut board_size = (0_usize, 0_usize);
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let mut start_pos = (0_usize, 0_usize);
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let mut end_pos = (0_usize, 0_usize);
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for (row, line) in buffer
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.lines()
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.enumerate()
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.map(|(row, col)| (row, col.unwrap()))
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{
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board_size.0 += 1;
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board_size.1 = if board_size.1 == 0 {
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line.len()
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} else {
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board_size.1
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};
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for (col, val) in line.as_bytes().iter().enumerate() {
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let height = match val {
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b'E' => {
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end_pos = (row, col);
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25
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}
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b'S' => {
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start_pos = (row, col);
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0
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}
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x => x - b'a',
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};
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board.push(Square {
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pos: (row, col),
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height,
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});
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}
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}
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let mut distances = std::iter::repeat(None)
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.take(board.len())
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.collect::<Vec<Option<u64>>>();
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let index = board_size.1 * end_pos.0 + end_pos.1;
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distances[index] = Some(0);
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let mut game = Game {
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board,
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distances,
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board_size,
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start_pos,
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end_pos,
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};
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game._set_distances();
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game
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}
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}
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impl Game {
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fn pos_to_index(&self, pos: &(usize, usize)) -> usize {
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self.board_size.1 * pos.0 + pos.1
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}
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fn _get_adjacent_from(&self, pos: &(usize, usize)) -> Vec<(usize, usize)> {
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let mut vec = Vec::new();
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let index = self.pos_to_index(pos);
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if pos.0 != 0 {
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let new_pos = (pos.0 - 1, pos.1);
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let new_index = self.pos_to_index(&new_pos);
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if self
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.board
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.get(new_index)
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.unwrap()
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.can_go_to(self.board.get(index).unwrap())
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{
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vec.push(new_pos);
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}
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}
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if pos.0 + 1 < self.board_size.0 {
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let new_pos = (pos.0 + 1, pos.1);
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let new_index = self.pos_to_index(&new_pos);
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if self.board[new_index].can_go_to(&self.board[index]) {
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vec.push(new_pos);
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}
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}
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if pos.1 != 0 {
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let new_pos = (pos.0, pos.1 - 1);
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let new_index = self.pos_to_index(&new_pos);
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if self.board[new_index].can_go_to(&self.board[index]) {
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vec.push(new_pos);
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}
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}
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if pos.1 + 1 < self.board_size.1 {
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let new_pos = (pos.0, pos.1 + 1);
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let new_index = self.pos_to_index(&new_pos);
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if self.board[new_index].can_go_to(&self.board[index]) {
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vec.push(new_pos);
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}
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}
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vec
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}
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fn _set_distances(&mut self) {
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let mut queue = VecDeque::new();
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queue.push_back(self.end_pos);
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while let Some(cur_pos) = queue.pop_front() {
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let adjacent = self._get_adjacent_from(&cur_pos);
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let cur_index = self.pos_to_index(&cur_pos);
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let cur_dist = self.distances.get(cur_index).unwrap().unwrap();
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adjacent
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.iter()
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.filter(|pos| {
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let index = self.pos_to_index(pos);
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match self.distances.get(index).unwrap() {
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None => {
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self.distances[index] = Some(cur_dist + 1);
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true
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}
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Some(check_dist) if *check_dist > cur_dist + 1 => {
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self.distances[index] = Some(cur_dist + 1);
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true
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}
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_ => false,
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}
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})
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.for_each(|check_pos| {
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queue.push_back(*check_pos);
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});
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}
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}
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pub fn get_distance_to_end(&self, pos: &(usize, usize)) -> Option<u64> {
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*self.distances.get(self.pos_to_index(pos)).unwrap()
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}
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pub fn get_all_at_height(&self, height: u8) -> Vec<Square> {
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self.board
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.iter()
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.filter(|x| x.height == height)
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.copied()
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.collect()
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}
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}
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fn main() -> Result<(), BoxError> {
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let file = File::open("./test.txt")?;
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let game: Game = file.into();
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let start = game.start_pos;
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let s = game
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.get_distance_to_end(&start)
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.expect("No end to this game");
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println!("Part 1: {s}");
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let shortest = game
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.get_all_at_height(0)
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.iter()
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.filter_map(|x| game.get_distance_to_end(&x.pos))
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.min()
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.expect("problem");
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println!("Part 2: {shortest}");
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Ok(())
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}
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