feat: day 6 part 1

src/bin/06.rs

@@ -0,0 +1,248 @@
+advent_of_code::solution!(6);
+
+use std::iter::successors;
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+enum Dir {
+    Up,
+    Down,
+    Left,
+    Right,
+}
+
+impl Dir {
+    fn to_vec(&self) -> (i8, i8) {
+        match self {
+            Dir::Up    => ( 0, -1),
+            Dir::Right => ( 1,  0),
+            Dir::Down  => ( 0,  1),
+            Dir::Left  => (-1,  0),
+        }
+    }
+
+    fn rotate90(&self) -> Self {
+        match self {
+            Dir::Up => Dir::Right,
+            Dir::Right => Dir::Down,
+            Dir::Down => Dir::Left,
+            Dir::Left => Dir::Up,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+struct Pos {
+    x: usize,
+    y: usize,
+}
+
+impl Pos {
+    fn init(x: usize, y: usize) -> Pos {
+        Pos { x, y }
+    }
+
+    fn move_towards(&self, v: (i8, i8), max: &Self) -> Option<Self> {
+        let new_x: isize = self.x as isize + v.0 as isize;
+        let new_y: isize = self.y as isize + v.1 as isize;
+        if new_x >= 0
+            && (new_x as usize) < max.x
+            && new_y >= 0
+            && (new_y as usize) < max.y {
+            Some(Pos { x: new_x as usize, y: new_y as usize })
+        } else {
+            None
+        }
+    }
+
+    fn is_at_limit(&self, max: &Self) -> bool {
+        self.x == max.x - 1|| self.y == max.y - 1
+    }
+}
+
+#[derive(Clone, PartialEq)]
+struct Guard {
+    pos: Pos,
+    facing: Dir,
+}
+
+impl std::fmt::Debug for Guard {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        match self.facing {
+            Dir::Up => write!(f, "^"),
+            Dir::Left => write!(f, "<"),
+            Dir::Right => write!(f, ">"),
+            Dir::Down => write!(f, "V"),
+        }
+    }
+}
+
+#[derive(Clone)]
+struct State {
+    walls: Vec<Pos>,
+    walked: Vec<Guard>,
+    guard: Guard,
+    map_size: Pos,
+}
+
+impl std::fmt::Debug for State {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        writeln!(f, "Size: {:?}", self.map_size)?;
+        for y in 0..self.map_size.y {
+            for x in 0..self.map_size.x {
+                let pos = Pos { x, y };
+                if self.walls.contains(&pos) {
+                    write!(f, "#")?;
+                    continue;
+                }
+                // screw the cpu
+                let match_walk = self
+                    .walked.clone()
+                    .into_iter()
+                    .filter(|g| g.pos == pos)
+                    .collect::<Vec<_>>();
+                match match_walk.len() {
+                    0 => write!(f, ".")?,
+                    1 => write!(f, "{:?}", match_walk[0])?,
+                    _ => write!(f, "*")?,
+                }
+            }
+            writeln!(f)?;
+        }
+        Ok(())
+    }
+    
+}
+
+
+impl State {
+    fn step(self) -> Option<Self> {
+        if self.is_last_step() {
+            return None;
+        }
+        let guard_walk_direction = self.guard.facing.to_vec();
+        let guard_walk = successors(
+            Some(self.guard.pos),
+            |pos| {
+                if let Some(new_pos) = pos.move_towards(guard_walk_direction, &self.map_size) {
+                    if !self.walls.contains(&new_pos) {
+                        return Some(new_pos)
+                    }
+                }
+                None
+            }
+        )
+            .collect::<Vec<Pos>>();
+        let guard_new_pos = guard_walk.last().unwrap().clone();
+        let mut walked: Vec<Guard> = self.walked.clone();
+        walked.extend(
+            guard_walk.iter().map(|p| Guard { pos: p.clone(), facing: self.guard.facing })
+        );
+        
+        Some(Self {
+            guard: Guard {
+                pos: guard_new_pos,
+                facing: self.guard.facing.rotate90(),
+            },
+            walked: walked,
+            ..self
+        })
+    }
+
+    fn is_last_step(&self) -> bool {
+        self.guard.pos.is_at_limit(&self.map_size)
+    }
+}
+
+fn parse_line(line: &str, line_nb: usize) -> (Vec<Pos>, Option<Pos>) {
+    line
+        .chars()
+        .enumerate()
+        .fold(
+            (Vec::<Pos>::new(), None),
+            |(mut wpos, gpos), (pos, chr)| match chr {
+                '#' => {
+                    wpos.push(Pos::init(pos, line_nb));
+                    (wpos, gpos)
+                },
+                '^' => {
+                    (wpos, Some(Pos::init(pos, line_nb)))
+                },
+                _ => (wpos, gpos)
+            }
+        )
+}
+
+fn parse_input(input: &str) -> State {
+    let input = input.lines().collect::<Vec<_>>();
+    let size = Pos::init(
+        input[0].len(),
+        input.len()
+    );
+    let data = input
+        .into_iter()
+        .enumerate()
+        .map(|(nb, line)| parse_line(line, nb))
+        .fold(
+            (Vec::<Pos>::new(), None),
+            |(mut gl_wpos, gl_gpos), (wpos, gpos)| {
+                gl_wpos.extend(wpos);
+                match gpos {
+                    Some(_) => (gl_wpos, gpos),
+                    _ => (gl_wpos, gl_gpos),
+                }
+            }
+        );
+    if data.1.is_none() {
+        panic!("Guard position not found?!");
+    }
+    let guard: Guard = Guard {
+        pos: data.1.unwrap(),
+        facing: Dir::Up
+    };
+    State {
+        walls: data.0,
+        guard: guard.clone(),
+        walked: vec![guard],
+        map_size: size,
+    }
+}
+
+pub fn part_one(input: &str) -> Option<usize> {
+    let state = parse_input(input);
+    let last_state = successors(
+        Some(state),
+        |s| s.clone().step())
+        .last().unwrap();
+    // println!("{:?}", last_state);
+    let mut visited = last_state
+        .walked
+        .iter()
+        .map(|g| &g.pos)
+        .collect::<Vec<&Pos>>();
+    visited.sort();
+    visited.dedup();
+    
+    Some(visited.len())
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let state = parse_input(input);
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(41));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, None);
+    }
+}