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-rw-r--r--2018/src/bin/day_13.rs249
1 files changed, 249 insertions, 0 deletions
diff --git a/2018/src/bin/day_13.rs b/2018/src/bin/day_13.rs
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+extern crate advent_of_code_2018;
+use advent_of_code_2018::*;
+
+use std::error::Error;
+use std::path::PathBuf;
+
+// cargo watch -cs "cargo run --release --bin day_13"
+
+#[derive(Debug)]
+enum Road {
+ LeftRight,
+ UpDown,
+ LeftUpRightDown,
+ RightUpLeftDown,
+ Intersection,
+ None
+}
+
+#[derive(Debug)]
+struct Cart {
+ next_turn: TurnDirection,
+ facing: FacingDirection,
+ x: usize,
+ y: usize,
+ crashed: bool
+
+}
+
+#[derive(Debug, Clone, Copy)]
+enum FacingDirection {
+ Up,
+ Down,
+ Left,
+ Right
+}
+
+#[derive(Debug, Clone, Copy)]
+enum TurnDirection {
+ Left,
+ Straight,
+ Right
+}
+
+impl TurnDirection {
+ fn next(&self) -> TurnDirection {
+ use TurnDirection::*;
+
+ match *self {
+ Left => Straight,
+ Straight => Right,
+ Right => Left
+ }
+ }
+
+ fn rotate(&self, facing: &FacingDirection) -> FacingDirection {
+ match *self {
+ TurnDirection::Left => match *facing {
+ FacingDirection::Up => FacingDirection::Left,
+ FacingDirection::Left => FacingDirection::Down,
+ FacingDirection::Down => FacingDirection::Right,
+ FacingDirection::Right => FacingDirection::Up
+ },
+ TurnDirection::Right => match *facing {
+ FacingDirection::Up => FacingDirection::Right,
+ FacingDirection::Left => FacingDirection::Up,
+ FacingDirection::Down => FacingDirection::Left,
+ FacingDirection::Right => FacingDirection::Down
+ },
+ TurnDirection::Straight => facing.clone()
+ }
+ }
+}
+
+
+
+fn main() -> Result<(), Box<Error>> {
+ let input = read_file(&PathBuf::from("inputs/13.txt"))?;
+
+// for i in &input {
+// println!("{}", i);
+// }
+
+ let mut map: Vec<Vec<Road>> = Vec::new();
+ let mut carts: Vec<Cart> = Vec::new();
+
+ for (y, line) in input.iter().enumerate() {
+ let mut map_row = Vec::new();
+ for (x, c) in line.chars().enumerate() {
+ let tile = match c {
+ ' ' => Road::None,
+ '-' => Road::LeftRight,
+ '|' => Road::UpDown,
+ '/' => Road::LeftUpRightDown,
+ '\\' => Road::RightUpLeftDown,
+ '+' => Road::Intersection,
+ '^' => {
+ carts.push(Cart {
+ next_turn: TurnDirection::Left,
+ facing: FacingDirection::Up,
+ x: x,
+ y: y,
+ crashed: false
+ });
+ Road::UpDown
+ },
+ '<' => {
+ carts.push(Cart {
+ next_turn: TurnDirection::Left,
+ facing: FacingDirection::Left,
+ x: x,
+ y: y,
+ crashed: false
+ });
+ Road::LeftRight
+ },
+ 'v' => {
+ carts.push(Cart {
+ next_turn: TurnDirection::Left,
+ facing: FacingDirection::Down,
+ x: x,
+ y: y,
+ crashed: false
+ });
+ Road::UpDown
+ },
+ '>' => {
+ carts.push(Cart {
+ next_turn: TurnDirection::Left,
+ facing: FacingDirection::Right,
+ x: x,
+ y: y,
+ crashed: false
+ });
+ Road::LeftRight
+ },
+
+ _ => {
+ panic!("Unknown character {}", c);
+ }
+ };
+ map_row.push(tile);
+ }
+ map.push(map_row);
+ }
+
+ while carts.len() > 1 {
+ carts.sort_unstable_by(|a, b| a.y.cmp(&b.y).then(a.x.cmp(&b.x)));
+
+ for i in 0..carts.len() {
+ {
+ let mut cart = &mut carts[i];
+ let road = &map[cart.y][cart.x];
+
+ match (road, cart.facing, cart.next_turn) {
+ (Road::LeftRight, FacingDirection::Left, _) => {
+ cart.x -= 1;
+ },
+ (Road::LeftRight, FacingDirection::Right, _) => {
+ cart.x += 1;
+ },
+ (Road::LeftRight, _, _) => {
+ panic!("Sideways cart heading left-right");
+ },
+
+ (Road::UpDown, FacingDirection::Up, _) => {
+ cart.y -= 1;
+ },
+ (Road::UpDown, FacingDirection::Down, _) => {
+ cart.y += 1;
+ },
+ (Road::UpDown, _, _) => {
+ panic!("Sideways cart heading up-down");
+ },
+
+ // /
+ (Road::LeftUpRightDown, FacingDirection::Down, _) => {
+ cart.x -= 1;
+ cart.facing = FacingDirection::Left;
+ },
+ (Road::LeftUpRightDown, FacingDirection::Right, _) => {
+ cart.y -= 1;
+ cart.facing = FacingDirection::Up;
+ },
+ (Road::LeftUpRightDown, FacingDirection::Left, _) => {
+ cart.y += 1;
+ cart.facing = FacingDirection::Down;
+ },
+ (Road::LeftUpRightDown, FacingDirection::Up, _) => {
+ cart.x += 1;
+ cart.facing = FacingDirection::Right;
+ },
+
+ // \
+ (Road::RightUpLeftDown, FacingDirection::Up, _) => {
+ cart.x -= 1;
+ cart.facing = FacingDirection::Left;
+ },
+ (Road::RightUpLeftDown, FacingDirection::Left, _) => {
+ cart.y -= 1;
+ cart.facing = FacingDirection::Up;
+ },
+ (Road::RightUpLeftDown, FacingDirection::Right, _) => {
+ cart.y += 1;
+ cart.facing = FacingDirection::Down;
+ },
+ (Road::RightUpLeftDown, FacingDirection::Down, _) => {
+ cart.x += 1;
+ cart.facing = FacingDirection::Right;
+ },
+
+ (Road::Intersection, f, d) => {
+ cart.facing = d.rotate(&f);
+ cart.next_turn = d.next();
+ match cart.facing {
+ FacingDirection::Up => { cart.y -= 1 },
+ FacingDirection::Down => { cart.y += 1 },
+ FacingDirection::Left => { cart.x -= 1 },
+ FacingDirection::Right => { cart.x += 1 },
+ }
+ },
+
+ (Road::None, _, _) => {
+ panic!("Offroad cart!");
+ }
+
+ }
+
+ }
+
+ let collisions = carts.iter()
+ .enumerate()
+ .filter(|(other_i, other)| *other_i != i && other.x == carts[i].x && other.y == carts[i].y)
+ .map(|(other_i, _)| other_i)
+ .collect::<Vec<_>>();
+ for other_i in collisions {
+ let crash_location = (carts[i].x, carts[i].y);
+ debug!(crash_location);
+ carts[i].crashed = true;
+ carts[other_i].crashed = true;
+ }
+ }
+
+ carts.retain(|cart| !cart.crashed);
+ }
+
+ debug!(carts);
+
+ Ok(())
+}