103 lines
2.5 KiB
Rust
103 lines
2.5 KiB
Rust
use std::error::Error;
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use std::fs::File;
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use std::io::{self, BufRead};
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#[derive(PartialEq, Copy, Clone)]
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enum Movement {
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North(u32),
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South(u32),
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East(u32),
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West(u32),
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Forward(u32),
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TurnLeft(u32),
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TurnRight(u32),
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}
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fn line_to_movement(line: &str) -> Movement {
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let cmd = line.get(0..1).unwrap();
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let arg: u32 = line.get(1..).unwrap().parse().unwrap();
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match cmd {
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"N" => Movement::North(arg),
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"S" => Movement::South(arg),
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"W" => Movement::West(arg),
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"E" => Movement::East(arg),
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"F" => Movement::Forward(arg),
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"R" => Movement::TurnRight(arg),
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"L" => Movement::TurnLeft(arg),
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_ => panic!("Unkown command: {}", line),
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}
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}
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struct Ship {
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x: i32,
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y: i32,
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waypoint_x: i32,
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waypoint_y: i32,
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}
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impl Ship {
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fn new() -> Ship {
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Ship {
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x: 0,
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y: 0,
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waypoint_x: 10,
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waypoint_y: -1,
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}
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}
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fn get_manhattan_distance(&self) -> u32 {
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self.x.abs() as u32 + self.y.abs() as u32
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}
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fn do_turn_left(&mut self, arg: u32) {
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for _ in 0..(arg / 90) {
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let wp_x = self.waypoint_x;
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let wp_y = self.waypoint_y;
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self.waypoint_x = wp_y;
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self.waypoint_y = -wp_x;
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}
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}
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fn do_turn_right(&mut self, arg: u32) {
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for _ in 0..(arg / 90) {
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let wp_x = self.waypoint_x;
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let wp_y = self.waypoint_y;
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self.waypoint_x = -wp_y;
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self.waypoint_y = wp_x;
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}
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}
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fn do_move(&mut self, m: Movement) {
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match m {
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Movement::North(d) => self.waypoint_y -= d as i32,
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Movement::South(d) => self.waypoint_y += d as i32,
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Movement::West(d) => self.waypoint_x -= d as i32,
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Movement::East(d) => self.waypoint_x += d as i32,
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Movement::Forward(d) => {
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self.x += self.waypoint_x * d as i32;
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self.y += self.waypoint_y * d as i32;
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}
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Movement::TurnLeft(arg) => self.do_turn_left(arg),
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Movement::TurnRight(arg) => self.do_turn_right(arg),
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};
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}
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}
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fn main() -> Result<(), Box<dyn Error>> {
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let file = File::open("inputs/day12.txt")?;
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let lines = io::BufReader::new(file).lines().map(|l| l.unwrap());
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let moves = lines.map(|l| line_to_movement(&l));
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let ship = moves.fold(Ship::new(), |mut s, m| {
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s.do_move(m);
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s
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});
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println!("Distance: {}", ship.get_manhattan_distance());
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Ok(())
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}
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