Cleanup for 2022 day 9: Turned into a lib and introduced parse errors
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Burnus
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3 changed files with 121 additions and 101 deletions
121
2022/day09-rope_bridging/src/lib.rs
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121
2022/day09-rope_bridging/src/lib.rs
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use core::fmt::Display;
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use std::num::ParseIntError;
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use std::collections::HashSet;
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#[derive(Debug, PartialEq, Eq)]
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pub enum ParseError<'a> {
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ParseIntError(std::num::ParseIntError),
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UnexpectedDirection(&'a str),
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}
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impl From<ParseIntError> for ParseError<'_> {
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fn from(value: ParseIntError) -> Self {
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Self::ParseIntError(value)
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}
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}
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impl Display for ParseError<'_> {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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match self {
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Self::ParseIntError(e) => write!(f, "Unable to parse into integer: {e}"),
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Self::UnexpectedDirection(c) => write!(f, "Trying to parse unexpected character {c} into direction"),
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}
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}
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}
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enum Direction {
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Left,
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Right,
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Up,
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Down,
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}
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#[derive(PartialEq, Eq, Hash, Copy, Clone)]
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struct Position {
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x: i32,
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y: i32,
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}
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impl Position {
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fn perform_motion(&mut self, direction: &Direction) {
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match direction {
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Direction::Left => self.x-=1,
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Direction::Right => self.x+=1,
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Direction::Up => self.y+=1,
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Direction::Down => self.y-=1,
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}
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}
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fn follow(&self, head: &Position) -> Self {
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let (dx, dy) = (head.x-self.x, head.y-self.y);
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match (dx, dy) {
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(2,0) => Self { x: self.x+1, y: self.y },
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(0,2) => Self { x: self.x, y: self.y+1 },
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(-2,0) => Self { x: self.x-1, y: self.y },
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(0,-2) => Self { x: self.x, y: self.y-1},
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(2,2)| (2,1) | (1,2) => Self { x: self.x+1, y: self.y+1 },
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(2,-2) | (2,-1) | (1,-2) => Self { x: self.x+1, y: self.y-1 },
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(-2,-2) | (-2,-1) | (-1,-2) => Self { x: self.x-1, y: self.y-1 },
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(-2,2) | (-2,1) |(-1,2) => Self { x: self.x-1, y: self.y+1 },
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_ => *self,
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}
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}
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}
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fn parse_head_movement(instruction: &str) -> Result<(Direction, i32), ParseError> {
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let direction = match &instruction[0..=0] {
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"L" => Ok(Direction::Left),
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"R" => Ok(Direction::Right),
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"U" => Ok(Direction::Up),
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"D" => Ok(Direction::Down),
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e => Err(ParseError::UnexpectedDirection(e)),
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}?;
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let count = instruction[2..].parse()?;
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Ok((direction, count))
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}
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fn get_visited(head_movements: &[(Direction, i32)], rope_length: usize) -> HashSet<Position> {
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let mut positions = vec![Position { x:0, y: 0 }; rope_length];
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let mut visited = HashSet::new();
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visited.insert(positions[0]);
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for (head_direction, count) in head_movements {
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for _ in 0..*count {
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positions[0].perform_motion(head_direction);
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for i in 1..rope_length {
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positions[i] = positions[i].follow(&positions[i-1]);
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}
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visited.insert(positions[rope_length-1]);
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}
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}
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visited
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}
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pub fn run(input: &str) -> Result<(usize, usize), ParseError> {
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let movements: Vec<_> = input.lines().map(parse_head_movement).collect::<Result<Vec<_>, _>>()?;
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let first = get_visited(&movements, 2).len();
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let second = get_visited(&movements, 10).len();
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Ok((first, second))
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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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use std::fs::read_to_string;
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fn read_file(name: &str) -> String {
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read_to_string(name).expect(&format!("Unable to read file: {name}")[..]).trim().to_string()
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}
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#[test]
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fn test_sample() {
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let sample_input = read_file("tests/sample_input");
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assert_eq!(run(&sample_input), Ok((13, 1)));
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}
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#[test]
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fn test_challenge() {
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let challenge_input = read_file("tests/challenge_input");
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assert_eq!(run(&challenge_input), Ok((6376, 2607)));
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}
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}
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@ -1,101 +0,0 @@
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use std::fs;
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use std::collections::HashSet;
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enum Direction {
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Left,
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Right,
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Up,
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Down,
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}
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#[derive(PartialEq, Eq, Hash, Copy, Clone)]
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struct Position {
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x: i32,
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y: i32,
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}
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impl Position {
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fn perform_motion(&mut self, direction: &Direction) {
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match direction {
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Direction::Left => self.x-=1,
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Direction::Right => self.x+=1,
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Direction::Up => self.y+=1,
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Direction::Down => self.y-=1,
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}
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}
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fn follow(&self, head: &Position) -> Self {
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let (dx, dy) = (head.x-self.x, head.y-self.y);
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match (dx, dy) {
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(2,0) => Self { x: self.x+1, y: self.y },
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(0,2) => Self { x: self.x, y: self.y+1 },
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(-2,0) => Self { x: self.x-1, y: self.y },
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(0,-2) => Self { x: self.x, y: self.y-1},
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(2,2)| (2,1) | (1,2) => Self { x: self.x+1, y: self.y+1 },
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(2,-2) | (2,-1) | (1,-2) => Self { x: self.x+1, y: self.y-1 },
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(-2,-2) | (-2,-1) | (-1,-2) => Self { x: self.x-1, y: self.y-1 },
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(-2,2) | (-2,1) |(-1,2) => Self { x: self.x-1, y: self.y+1 },
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_ => *self,
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}
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}
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}
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fn read_file(path: &str) -> String {
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fs::read_to_string(path)
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.expect("File not Found")
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}
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fn parse_head_movement(instruction: &str) -> (Direction, i32) {
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let direction = match &instruction[0..=0] {
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"L" => Direction::Left,
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"R" => Direction::Right,
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"U" => Direction::Up,
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"D" => Direction::Down,
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_ => panic!("Unknown Direction"),
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};
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let count = instruction[2..].parse().unwrap();
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(direction, count)
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}
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fn get_visited(head_movements: &str, rope_length: usize) -> HashSet<Position> {
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let mut positions = vec![Position { x:0, y: 0 }; rope_length];
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let mut visited = HashSet::new();
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visited.insert(positions[0]);
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for instruction in head_movements.lines() {
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let (head_direction, count) = parse_head_movement(instruction);
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for _ in 0..count {
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positions[0].perform_motion(&head_direction);
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for i in 1..rope_length {
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positions[i] = positions[i].follow(&positions[i-1]);
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}
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visited.insert(positions[rope_length-1]);
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}
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}
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visited
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}
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fn main() {
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//let head_movements = read_file("sample_input");
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let head_movements = read_file("input");
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let visited_fixed = get_visited(&head_movements, 2);
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let visited_loose = get_visited(&head_movements, 10);
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println!("The fixed tail visited a total of {} positions.", visited_fixed.len());
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println!("The loose tail visited a total of {} positions.", visited_loose.len());
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}
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#[test]
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fn sample_input() {
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let head_movements = read_file("tests/sample_input");
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assert_eq!(get_visited(&head_movements, 2).len(), 13);
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assert_eq!(get_visited(&head_movements, 10).len(), 1);
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}
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#[test]
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fn challenge_input() {
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let head_movements = read_file("tests/input");
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assert_eq!(get_visited(&head_movements, 2).len(), 6376);
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assert_eq!(get_visited(&head_movements, 10).len(), 2607);
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}
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