Split lib from main
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day12/src/lib.rs
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287
day12/src/lib.rs
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@ -0,0 +1,287 @@
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mod node;
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use core::fmt;
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use node::Node;
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use aoc_shared::enums::Direction;
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use aoc_shared::grid::Grid as BaseGrid;
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use aoc_shared::impl_grid_newtype;
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#[derive(Debug, Copy, Clone, PartialEq)]
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enum CellType {
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Start,
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End,
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Waypoint(u8),
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}
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#[derive(Debug, Clone)]
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struct Cell {
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kind: CellType,
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idx: usize,
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coord: (usize, usize),
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}
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impl Cell {
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pub fn new(kind: CellType, idx: usize, coord: (usize, usize)) -> Self {
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Cell { kind, idx, coord }
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}
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pub fn get_height(&self) -> u8 {
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match self.kind {
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CellType::Start => 0,
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CellType::End => 25,
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CellType::Waypoint(c) => c,
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}
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}
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}
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// ----------------------------------------------------------------------------
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pub struct Grid<T>(BaseGrid<T>);
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impl_grid_newtype!(Grid, BaseGrid<Cell>, Cell);
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impl Grid<Cell> {
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pub fn from_file_str(file_str: &str) -> Self {
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let first_line = file_str.lines().next().unwrap();
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let width = first_line.len();
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let mut grid = Grid::new(width);
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let mut idx = 0usize;
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for c in file_str.chars() {
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let kind = match c {
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'S' => CellType::Start,
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'E' => CellType::End,
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'a'..='z' => CellType::Waypoint(c as u8 - b'a'),
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'\r' | '\n' => continue,
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_ => panic!("Invalid character: {c}"),
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};
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let (x, y) = (idx % width, idx / width);
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let cell = Cell::new(kind, idx, (x, y));
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grid.vec.push(cell);
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idx += 1;
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}
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grid
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}
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fn find_pos(&self, value: CellType) -> Option<usize> {
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self.vec.iter().position(|item| item.kind == value)
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}
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pub fn print(&self) {
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for r in 0usize..self.num_rows() {
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let range = self.row_first_idx(r)..=self.row_last_idx(r);
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let line: String = self.vec[range]
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.iter()
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.map(|n| (n.get_height() + b'a') as char)
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.collect();
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println!("{}", line);
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}
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}
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fn get_index_for_move(&self, from: usize, dir: Direction) -> Option<usize> {
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let (mut x, mut y) = self.idx_xy(from);
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match dir {
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Direction::Up => {
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if y >= 1 {
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y -= 1;
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} else {
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return None;
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}
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}
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Direction::Down => {
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if y < self.num_rows() - 1 {
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y += 1;
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} else {
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return None;
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}
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}
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Direction::Left => {
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if x >= 1 {
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x -= 1;
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} else {
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return None;
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}
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}
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Direction::Right => {
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if x < self.num_cols() - 1 {
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x += 1;
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} else {
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return None;
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}
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}
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};
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Some(self.xy_idx(x, y))
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}
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fn is_valid_move(&self, start: usize, end: usize) -> bool {
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// Is the item within the grid?
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let start_char = self.get(start);
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let end_char = self.get(end);
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if start_char.is_none() || end_char.is_none() {
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return false;
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}
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let start_char = start_char.unwrap();
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let end_char = end_char.unwrap();
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let start_elevation = start_char.get_height();
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let end_elevation = end_char.get_height();
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if (end_elevation < start_elevation) || end_elevation.abs_diff(start_elevation) > 1 {
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return false;
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}
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let ((start_x, start_y), (end_x, end_y)) = (start_char.coord, end_char.coord);
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let x_diff = end_x.abs_diff(start_x);
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let y_diff = end_y.abs_diff(start_y);
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// Have we moved 0 or 1 in a cardinal direction?
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matches!((x_diff, y_diff), (0, 0) | (0, 1) | (1, 0))
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}
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fn find_moves(&self, start: usize) -> Vec<usize> {
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[
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Direction::Up,
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Direction::Down,
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Direction::Left,
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Direction::Right,
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]
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.into_iter()
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.filter_map(|d| self.get_index_for_move(start, d))
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.collect()
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}
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fn find_valid_moves(&self, start: usize) -> Vec<usize> {
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self.find_moves(start)
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.into_iter()
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.filter(|m| self.is_valid_move(start, *m))
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.collect()
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}
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fn has_valid_neighbor(&self, idx: usize) -> bool {
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!self.find_valid_moves(idx).is_empty()
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}
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}
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impl fmt::Debug for Grid<Cell> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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for r in 0usize..self.num_rows() {
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let range = self.row_first_idx(r)..=self.row_last_idx(r);
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let line: String = self.vec[range]
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.iter()
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.map(|n| (n.get_height() + b'a') as char)
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.collect();
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writeln!(f, "{}", line)?;
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}
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Ok(())
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}
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}
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// ----------------------------------------------------------------------------
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#[derive(Debug)]
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pub struct Pathfinder {
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start_idx: usize,
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end_idx: usize,
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grid: Grid<Cell>,
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tree: Node,
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}
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impl Pathfinder {
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pub fn from_file_str(file_str: &str) -> Self {
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let mut pf = Pathfinder {
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start_idx: 0,
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end_idx: 0,
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grid: Grid::from_file_str(file_str),
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tree: Node::default(),
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};
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let start = pf.grid.find_pos(CellType::Start).unwrap();
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let end = pf.grid.find_pos(CellType::End).unwrap();
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pf.start_idx = start;
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pf.end_idx = end;
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pf.tree.idx = start;
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pf
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}
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fn add_children(&mut self, node: &mut Node, idx: usize) {
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let possible_moves = self.grid.find_valid_moves(idx);
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if possible_moves.is_empty() {
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return;
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}
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for m in possible_moves {
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if node.contains(m) {
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continue;
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}
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let n = node.add_child(m);
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if m != self.end_idx {
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self.add_children(n, m);
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} else {
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break;
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}
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}
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}
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fn build_tree(&mut self) {
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let mut tree = { self.tree.clone() };
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let idx = { self.start_idx };
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self.add_children(&mut tree, idx);
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self.tree = tree;
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}
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fn get_paths(&self) -> impl Iterator<Item = &Node> {
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self.tree
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.get_leaves()
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.into_iter()
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.filter(|n| n.idx == self.end_idx)
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}
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pub fn find_shortest_path(&mut self) -> &Node {
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self.build_tree();
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self.get_paths()
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.min_by(|a, b| a.get_len().cmp(&b.get_len()))
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.unwrap()
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn get_test_data() -> &'static str {
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include_str!("test-input.txt")
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}
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fn get_finder() -> Pathfinder {
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Pathfinder::from_file_str(get_test_data())
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}
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#[test]
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fn find_valid_moves() {
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let finder = get_finder();
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assert_eq!(finder.grid.find_valid_moves(finder.start_idx), vec![8, 1]);
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assert_eq!(finder.grid.find_valid_moves(8), vec![0, 16, 9]);
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}
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#[test]
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fn find_shortest_path() {
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let mut finder = get_finder();
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let shortest = finder.find_shortest_path();
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assert_eq!(shortest.get_len(), 31);
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}
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}
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@ -1,281 +1,7 @@
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mod node;
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use node::Node;
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use aoc_shared::enums::Direction;
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use aoc_shared::grid::Grid as BaseGrid;
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use aoc_shared::impl_grid_newtype;
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#[derive(Debug, Copy, Clone, PartialEq)]
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enum CellType {
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Start,
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End,
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Waypoint(u8),
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}
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#[derive(Debug, Clone)]
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struct Cell {
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kind: CellType,
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idx: usize,
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coord: (usize, usize),
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}
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impl Cell {
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pub fn new(kind: CellType, idx: usize, coord: (usize, usize)) -> Self {
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Cell { kind, idx, coord }
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}
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pub fn get_height(&self) -> u8 {
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match self.kind {
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CellType::Start => 0,
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CellType::End => 25,
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CellType::Waypoint(c) => c,
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}
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}
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}
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// ----------------------------------------------------------------------------
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#[derive(Debug)]
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pub struct Grid<T>(BaseGrid<T>);
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impl_grid_newtype!(Grid, BaseGrid<Cell>, Cell);
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impl Grid<Cell> {
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pub fn from_file_str(file_str: &str) -> Self {
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let first_line = file_str.lines().next().unwrap();
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let width = first_line.len();
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let mut grid = Grid::new(width);
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let mut idx = 0usize;
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for c in file_str.chars() {
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let kind = match c {
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'S' => CellType::Start,
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'E' => CellType::End,
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'a'..='z' => CellType::Waypoint(c as u8 - b'a'),
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'\r' | '\n' => continue,
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_ => panic!("Invalid character: {c}"),
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};
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let (x, y) = (idx % width, idx / width);
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let cell = Cell::new(kind, idx, (x, y));
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grid.vec.push(cell);
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idx += 1;
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}
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grid
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}
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fn find_pos(&self, value: CellType) -> Option<usize> {
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self.vec.iter().position(|item| item.kind == value)
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}
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pub fn print(&self) {
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for r in 0usize..self.num_rows() {
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let range = self.row_first_idx(r)..=self.row_last_idx(r);
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let line: String = self.vec[range]
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.iter()
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.map(|n| (n.get_height() + b'a') as char)
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.collect();
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println!("{}", line);
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}
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}
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fn get_index_for_move(&self, from: usize, dir: Direction) -> Option<usize> {
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let (mut x, mut y) = self.idx_xy(from);
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match dir {
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Direction::Up => {
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if y >= 1 {
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y -= 1;
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} else {
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return None;
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}
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}
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Direction::Down => {
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if y < self.num_rows() - 1 {
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y += 1;
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} else {
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return None;
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}
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}
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Direction::Left => {
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if x >= 1 {
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x -= 1;
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} else {
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return None;
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}
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}
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Direction::Right => {
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if x < self.num_cols() - 1 {
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x += 1;
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} else {
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return None;
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}
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}
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};
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Some(self.xy_idx(x, y))
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}
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fn is_valid_move(&self, start: usize, end: usize) -> bool {
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// Is the item within the grid?
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let start_char = self.get(start);
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let end_char = self.get(end);
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if start_char.is_none() || end_char.is_none() {
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return false;
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}
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let start_char = start_char.unwrap();
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let end_char = end_char.unwrap();
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let start_elevation = start_char.get_height();
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let end_elevation = end_char.get_height();
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if (end_elevation < start_elevation) || end_elevation.abs_diff(start_elevation) > 1 {
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return false;
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}
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let ((start_x, start_y), (end_x, end_y)) = (start_char.coord, end_char.coord);
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let x_diff = end_x.abs_diff(start_x);
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let y_diff = end_y.abs_diff(start_y);
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// Have we moved 0 or 1 in a cardinal direction?
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matches!((x_diff, y_diff), (0, 0) | (0, 1) | (1, 0))
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}
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fn find_moves(&self, start: usize) -> Vec<usize> {
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[
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Direction::Up,
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Direction::Down,
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Direction::Left,
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Direction::Right,
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]
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.into_iter()
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.filter_map(|d| self.get_index_for_move(start, d))
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.collect()
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}
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fn find_valid_moves(&self, start: usize) -> Vec<usize> {
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self.find_moves(start)
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.into_iter()
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.filter(|m| self.is_valid_move(start, *m))
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.collect()
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}
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fn has_valid_neighbor(&self, idx: usize) -> bool {
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!self.find_valid_moves(idx).is_empty()
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}
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}
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// ----------------------------------------------------------------------------
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#[derive(Debug)]
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pub struct Pathfinder {
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start_idx: usize,
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end_idx: usize,
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grid: Grid<Cell>,
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tree: Node,
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}
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impl Pathfinder {
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pub fn from_file_str(file_str: &str) -> Self {
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let mut pf = Pathfinder {
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start_idx: 0,
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end_idx: 0,
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grid: Grid::from_file_str(file_str),
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tree: Node::default(),
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};
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let start = pf.grid.find_pos(CellType::Start).unwrap();
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let end = pf.grid.find_pos(CellType::End).unwrap();
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pf.start_idx = start;
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pf.end_idx = end;
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pf.tree.idx = start;
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pf
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}
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fn add_children(&mut self, node: &mut Node, idx: usize) {
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let possible_moves = self.grid.find_valid_moves(idx);
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if possible_moves.is_empty() {
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return;
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}
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for m in possible_moves {
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if node.contains(m) {
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continue;
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}
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let n = node.add_child(m);
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if m != self.end_idx {
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self.add_children(n, m);
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} else {
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break;
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}
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}
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}
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fn build_tree(&mut self) {
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let mut tree = { self.tree.clone() };
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let idx = { self.start_idx };
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self.add_children(&mut tree, idx);
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self.tree = tree;
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}
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fn get_paths(&self) -> impl Iterator<Item = &Node> {
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self.tree
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.get_leaves()
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.into_iter()
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.filter(|n| n.idx == self.end_idx)
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}
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pub fn find_shortest_path(&mut self) -> &Node {
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self.build_tree();
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self.get_paths()
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.min_by(|a, b| a.get_len().cmp(&b.get_len()))
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.unwrap()
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}
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}
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// ----------------------------------------------------------------------------
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||||
fn main() {
|
||||
let file_str = include_str!("input.txt");
|
||||
let mut finder = Pathfinder::from_file_str(file_str);
|
||||
let mut finder = ::day12::Pathfinder::from_file_str(file_str);
|
||||
let shortest_path = finder.find_shortest_path();
|
||||
|
||||
println!("Part 1: Fewest steps: {}", shortest_path.get_len());
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
|
||||
fn get_test_data() -> &'static str {
|
||||
include_str!("test-input.txt")
|
||||
}
|
||||
|
||||
fn get_finder() -> Pathfinder {
|
||||
Pathfinder::from_file_str(get_test_data())
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn find_valid_moves() {
|
||||
let finder = get_finder();
|
||||
|
||||
assert_eq!(finder.grid.find_valid_moves(finder.start_idx), vec![8, 1]);
|
||||
assert_eq!(finder.grid.find_valid_moves(8), vec![0, 16, 9]);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn find_shortest_path() {
|
||||
let mut finder = get_finder();
|
||||
let shortest = finder.find_shortest_path();
|
||||
assert_eq!(shortest.get_len(), 31);
|
||||
}
|
||||
}
|
||||
|
||||
@ -20,9 +20,7 @@ impl Node {
|
||||
|
||||
self.append(child);
|
||||
|
||||
self.children
|
||||
.last_mut()
|
||||
.unwrap()
|
||||
self.children.last_mut().unwrap()
|
||||
}
|
||||
|
||||
fn append(&mut self, node: Node) -> &mut Self {
|
||||
@ -50,9 +48,7 @@ impl Node {
|
||||
|
||||
let mut leaves = Vec::new();
|
||||
|
||||
let children = self
|
||||
.children
|
||||
.iter();
|
||||
let children = self.children.iter();
|
||||
|
||||
for child in children {
|
||||
let mut child_leaves = child.get_leaves();
|
||||
|
||||
Reference in New Issue
Block a user