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|
use std::collections::{HashMap, HashSet};
static DAY: u8 = 6;
fn main() {
let input = advent::read_lines(DAY);
println!("{DAY}a: {}", Map::new(&input).distinct_positions());
println!("{DAY}b: {}", 0);
}
#[derive(Eq, PartialEq, Hash, Clone)]
struct Position {
x: isize,
y: isize,
}
#[derive(Eq, PartialEq)]
enum Object {
Obstruction,
Floor,
Guard,
}
enum Direction {
Up,
Down,
Left,
Right,
}
impl Direction {
fn turn_right(&self) -> Direction {
match *self {
Direction::Up => Direction::Right,
Direction::Down => Direction::Left,
Direction::Left => Direction::Up,
Direction::Right => Direction::Down,
}
}
}
impl Object {
fn new(c: char) -> Object {
match c {
'#' => Object::Obstruction,
'.' => Object::Floor,
'^' => Object::Guard,
_ => unimplemented!(),
}
}
}
struct Guard {
pos: Position,
direction: Direction,
}
impl Guard {
fn next_pos(&self) -> Position {
match self.direction {
Direction::Up => Position { x: self.pos.x, y: self.pos.y - 1 },
Direction::Down => Position { x: self.pos.x, y: self.pos.y + 1 },
Direction::Left => Position { x: self.pos.x - 1, y: self.pos.y },
Direction::Right => Position { x: self.pos.x + 1, y: self.pos.y },
}
}
}
struct Map {
map: HashMap<Position, Object>,
guard: Guard,
max_dimension: Position,
}
impl Map {
fn new(input: &[String]) -> Map {
let mut map = HashMap::new();
let mut guard = Guard { pos: Position { x: 0, y: 0 }, direction: Direction::Up };
for (y, line) in input.iter().enumerate() {
for (x, c) in line.chars().enumerate() {
let pos = Position { x: x as isize, y: y as isize };
let obj = Object::new(c);
if obj == Object::Guard {
guard.pos = pos.clone();
map.insert(pos, Object::Floor);
} else {
map.insert(pos, Object::new(c));
}
}
}
Map { map, guard, max_dimension: Position { x: input[0].len() as isize, y: input.len() as isize } }
}
fn distinct_positions(&mut self) -> usize {
let mut visited = HashSet::new();
loop {
let next_pos = self.guard.next_pos();
if next_pos.x < 0 || next_pos.x >= self.max_dimension.x || next_pos.y < 0 || next_pos.y >= self.max_dimension.y {
break;
}
match self.map.get(&next_pos).unwrap() {
Object::Floor => {
self.guard.pos = next_pos.clone();
visited.insert(next_pos);
},
Object::Obstruction => {
self.guard.direction = self.guard.direction.turn_right();
continue;
},
_ => unimplemented!(),
}
}
visited.len()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let input = [
"....#.....",
".........#",
"..........",
"..#.......",
".......#..",
"..........",
".#..^.....",
"........#.",
"#.........",
"......#...",
].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
assert_eq!(Map::new(&input).distinct_positions(), 41);
}
}
|
