Made my initial solution work
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5A0CBFE3C3377FAA
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@ -1,6 +1,6 @@
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#![feature(test)]
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use core::panic;
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use std::collections::HashMap;
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use std::collections::{HashMap, VecDeque};
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use anyhow::Result;
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use aoc::Solver;
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@ -180,46 +180,51 @@ impl Maze {
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}
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}
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// #[derive(Debug, PartialEq, Eq, Clone, Copy)]
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// enum Loop {
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// North,
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// East,
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// South,
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// West,
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// Inner,
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// }
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//
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// impl Loop {
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// fn from(direction: (isize, isize)) -> Self {
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// match direction {
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// (0, -1) => Self::North,
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// (1, 0) => Self::East,
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// (0, 1) => Self::South,
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// (-1, 0) => Self::West,
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// _ => unreachable!("Invalid direction"),
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// }
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// }
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//
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// fn offset(&self) -> (isize, isize) {
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// match self {
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// Loop::North => (0, -1),
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// Loop::East => (1, 0),
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// Loop::South => (0, 1),
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// Loop::West => (-1, 0),
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// Loop::Inner => (0, 0),
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// }
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// }
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// }
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//
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// fn flood_fill(position: (isize, isize), map: &mut HashMap<(isize, isize), Loop>) {
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// if map.get(&position).is_none() {
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// map.insert(position, Loop::Inner);
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//
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// for direction in DIRECTIONS {
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// flood_fill((position.0 + direction.0, position.1 + direction.1), map)
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// }
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// }
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// }
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#[derive(Debug, PartialEq, Eq, Clone, Copy)]
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enum Loop {
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North,
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East,
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South,
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West,
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Inner,
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}
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impl Loop {
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fn from(direction: (isize, isize)) -> Self {
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match direction {
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(0, -1) => Self::North,
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(1, 0) => Self::East,
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(0, 1) => Self::South,
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(-1, 0) => Self::West,
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_ => unreachable!("Invalid direction"),
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}
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}
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fn offset(&self) -> (isize, isize) {
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match self {
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Loop::North => (0, -1),
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Loop::East => (1, 0),
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Loop::South => (0, 1),
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Loop::West => (-1, 0),
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Loop::Inner => (0, 0),
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}
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}
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}
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fn flood_fill(position: (isize, isize), map: &mut HashMap<(isize, isize), Loop>) {
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let mut queue = VecDeque::new();
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queue.push_back(position);
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while let Some(position) = queue.pop_front() {
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if map.get(&position).is_none() {
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map.insert(position, Loop::Inner);
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for direction in DIRECTIONS {
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queue.push_back((position.0 + direction.0, position.1 + direction.1));
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}
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}
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}
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}
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static DIRECTIONS: [(isize, isize); 4] = [(0, -1), (1, 0), (0, 1), (-1, 0)];
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@ -292,10 +297,11 @@ impl aoc::Solver for Day {
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}
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}
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// Alternate solution that works for the examples and is off-by-one for the actual input
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fn part2(input: &str) -> Self::Output2 {
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let mut position_start = (-1, -1);
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let maze: HashMap<(isize, isize), Maze> = input
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let end_direction;
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let mut maze: HashMap<(isize, isize), Maze> = input
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.lines()
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.enumerate()
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.flat_map(|(y, line)| {
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@ -311,11 +317,13 @@ impl aoc::Solver for Day {
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})
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.collect();
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let mut map = HashMap::new();
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if position_start == (-1, -1) {
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panic!("No valid start in input");
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}
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let mut map = HashMap::<(isize, isize), Maze>::new();
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let mut sides = (0, 0);
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let mut position_current = position_start;
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let mut position_previous = position_start;
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@ -335,12 +343,17 @@ impl aoc::Solver for Day {
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if let Some(tile_next) = maze.get(&position_next) {
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if tile_current.connects(tile_next, direction) {
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map.insert(position_current, *tile_current);
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map.insert(position_current, Loop::from(direction));
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position_previous = position_current;
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position_current = position_next;
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let s = tile_current.sides(direction);
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sides.0 += s.0;
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sides.1 += s.1;
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if position_current == position_start {
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end_direction = Loop::from(direction);
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break 'outer;
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}
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@ -352,165 +365,151 @@ impl aoc::Solver for Day {
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unreachable!("Unable to move forward...");
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}
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// It appears that the start can always be replaced with an F
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// Atleast in all the examples and my input
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map.insert(position_start, Maze::SouthEast);
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// Replace the start with the correct piece
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let start = match (end_direction, map.get(&position_start).unwrap()) {
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(Loop::North, Loop::North) | (Loop::South, Loop::South) => Maze::Vertical,
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(Loop::East, Loop::East) | (Loop::West, Loop::West) => Maze::Horizontal,
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(Loop::South, Loop::East) | (Loop::West, Loop::North) => Maze::NorthEast,
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(Loop::South, Loop::West) | (Loop::East, Loop::North) => Maze::NorthWest,
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(Loop::East, Loop::South) | (Loop::North, Loop::West) => Maze::SouthWest,
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(Loop::North, Loop::East) | (Loop::West, Loop::South) => Maze::SouthEast,
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_ => unreachable!(),
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};
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maze.insert(position_start, start);
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let bounds = (
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input.lines().map(|line| line.len()).max().unwrap(),
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input.lines().count(),
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);
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// Add the sides of the start
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let start_sides = start.sides(map.get(&position_start).unwrap().offset());
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sides.0 += start_sides.0;
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sides.1 += start_sides.1;
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let mut count = 0;
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let mut in_loop = false;
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let mut maybe = None;
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for y in 0..bounds.1 {
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for x in 0..bounds.0 {
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if let Some(entry) = map.get(&(x as isize, y as isize)) {
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match entry {
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Maze::Vertical => in_loop = !in_loop,
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Maze::Horizontal => {}
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dir @ (Maze::NorthEast | Maze::SouthEast) => maybe = Some(*dir),
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Maze::NorthWest => {
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if maybe == Some(Maze::SouthEast) {
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in_loop = !in_loop
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}
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// Determine if the loop was travelled clockwise or anti clockwise
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let clockwise = sides.0 > sides.1;
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let mut position_current = position_start;
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loop {
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let &direction = map.get(&position_current).unwrap();
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let tile = maze.get(&position_current).unwrap();
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// Get neighbouring tiles that are inside of the loop
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let checks = match direction {
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Loop::North => match tile {
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Maze::Vertical => {
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if clockwise {
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vec![(1, 0)]
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} else {
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vec![(-1, 0)]
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}
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Maze::SouthWest => {
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if maybe == Some(Maze::NorthEast) {
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in_loop = !in_loop
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}
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}
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Maze::Start => unreachable!("Start should have been replaced"),
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}
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} else if in_loop {
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count += 1;
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}
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Maze::NorthEast => {
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if clockwise {
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vec![]
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} else {
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vec![(-1, 0), (0, 1)]
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}
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}
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Maze::NorthWest => {
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if clockwise {
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vec![(1, 0), (0, 1)]
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} else {
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vec![]
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}
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}
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_ => unreachable!(),
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},
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Loop::East => match tile {
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Maze::Horizontal => {
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if clockwise {
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vec![(0, 1)]
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} else {
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vec![(0, -1)]
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}
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}
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Maze::NorthEast => {
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if clockwise {
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vec![(-1, 0), (0, 1)]
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} else {
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vec![]
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}
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}
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Maze::SouthEast => {
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if clockwise {
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vec![]
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} else {
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vec![(-1, 0), (0, -1)]
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}
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}
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_ => unreachable!(),
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},
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Loop::South => match tile {
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Maze::Vertical => {
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if clockwise {
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vec![(-1, 0)]
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} else {
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vec![(1, 0)]
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}
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}
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Maze::SouthWest => {
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if clockwise {
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vec![]
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} else {
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vec![(0, -1), (1, 0)]
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}
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}
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Maze::SouthEast => {
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if clockwise {
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vec![(0, -1), (-1, 0)]
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} else {
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vec![]
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}
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}
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_ => unreachable!(),
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},
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Loop::West => match tile {
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Maze::Horizontal => {
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if clockwise {
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vec![(0, -1)]
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} else {
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vec![(0, 1)]
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}
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}
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Maze::NorthWest => {
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if clockwise {
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vec![]
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} else {
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vec![(1, 0), (0, 1)]
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}
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}
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Maze::SouthWest => {
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if clockwise {
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vec![(1, 0), (0, -1)]
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} else {
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vec![]
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}
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}
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_ => unreachable!(),
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},
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Loop::Inner => unreachable!("Loop should not contain Inner"),
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};
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// Perform a floodfill from those neighbouring tiles
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for check in checks {
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let check = (position_current.0 + check.0, position_current.1 + check.1);
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flood_fill(check, &mut map);
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}
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let direction = direction.offset();
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position_current.0 += direction.0;
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position_current.1 += direction.1;
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if position_current == position_start {
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break;
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}
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}
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count
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// Count how many tiles are marked as inner
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map.iter()
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.filter(|(_, &value)| value == Loop::Inner)
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.count()
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}
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// Alternate solution that works for the examples and is off-by-one for the actual input
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// fn part2(input: &str) -> Self::Output2 {
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// let mut position_start = (-1, -1);
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// let maze: HashMap<(isize, isize), Maze> = input
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// .lines()
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// .enumerate()
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// .flat_map(|(y, line)| {
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// line.chars()
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// .enumerate()
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// .filter_map(|(x, c)| Maze::from(c).map(|maze| ((x as isize, y as isize), maze)))
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// .inspect(|(position, maze)| {
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// if *maze == Maze::Start {
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// position_start = *position
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// }
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// })
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// .collect::<Vec<_>>()
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// })
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// .collect();
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//
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// let mut map = HashMap::<(isize, isize), Loop>::new();
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//
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// if position_start == (-1, -1) {
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// panic!("No valid start in input");
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// }
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//
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// let mut sides = (0, 0);
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//
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// let mut position_current = position_start;
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// let mut position_previous = position_start;
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// 'outer: loop {
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// let tile_current = maze.get(&position_current).unwrap();
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//
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// for direction in DIRECTIONS {
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// let position_next = (
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// position_current.0 + direction.0,
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// position_current.1 + direction.1,
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// );
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//
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// // We are now allowed to go back to the previous position
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// if position_next == position_previous {
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// continue;
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// }
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//
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// if let Some(tile_next) = maze.get(&position_next) {
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// if tile_current.connects(tile_next, direction) {
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// map.insert(position_current, Loop::from(direction));
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//
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// position_previous = position_current;
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// position_current = position_next;
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//
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// let s = tile_current.sides(direction);
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// sides.0 += s.0;
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// sides.1 += s.1;
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//
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// if position_current == position_start {
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// break 'outer;
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// }
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//
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// continue 'outer;
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// }
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// }
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// }
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//
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// unreachable!("Unable to move forward...");
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// }
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//
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// let clockwise = sides.0 > sides.1;
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//
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// let mut position_current = position_start;
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// loop {
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// let &direction = map.get(&position_current).unwrap();
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//
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// let check = match direction {
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// Loop::North => {
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// if clockwise {
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// (1, 0)
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// } else {
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// (-1, 0)
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// }
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// }
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// Loop::East => {
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// if clockwise {
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// (0, 1)
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// } else {
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// (0, -1)
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// }
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// }
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// Loop::South => {
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// if clockwise {
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// (-1, 0)
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// } else {
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// (1, 0)
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// }
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// }
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// Loop::West => {
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// if clockwise {
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// (0, -1)
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// } else {
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// (0, 1)
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// }
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// }
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// Loop::Inner => unreachable!("Loop should not contain Inner"),
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// };
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// let check = (position_current.0 + check.0, position_current.1 + check.1);
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//
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// flood_fill(check, &mut map);
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//
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// let direction = direction.offset();
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//
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// position_current.0 += direction.0;
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// position_current.1 += direction.1;
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//
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// if position_current == position_start {
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// break;
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// }
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// }
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//
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// map.iter()
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// .filter(|(_, &value)| value == Loop::Inner)
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// .count()
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// }
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}
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