3 files changed, 506 insertions, 0 deletions

diff --git a/2022/22/a.rs b/2022/22/a.rs
new file mode 100644
index 0000000..40f9c44
--- /dev/null
+++ b/2022/22/a.rs
@@ -0,0 +1,81 @@
+use std::cmp::max;
+mod common;
+use common::*;
+
+#[derive(Copy, Clone, Debug)]
+pub struct Position {
+    pub i: usize,
+    pub j: usize,
+    pub d: Direction
+}
+
+pub struct Map {
+    pub tiles: Vec<Vec<Tile>>
+}
+
+type StepFn = fn(&Map, Position) -> Position;
+
+impl Map {
+    pub fn from_stdin() -> Map {
+        let mut maxlen = 0;
+        let mut tiles = vec![];
+        let mut line = String::new();
+        while std::io::stdin().read_line(&mut line).unwrap() > 1 {
+            let v = line[0..line.len()-1].as_bytes().iter()
+                .map(|b| Tile::from_byte(*b)).collect::<Vec<_>>();
+            maxlen = max(maxlen, v.len());
+            tiles.push(v);
+            line.clear();
+        }
+        for v in &mut tiles {
+            while v.len() < maxlen { v.push(Tile::Skip); }
+        }
+        Map { tiles }
+    }
+
+    pub fn start_position(&self) -> Position {
+        let first_valid = self.tiles[0].iter()
+            .position(|t| *t == Tile::Walk).unwrap();
+        Position { i: 0, j: first_valid, d: Direction::Right }
+    }
+
+    pub fn walk(&self, pos: Position, n: usize, step: StepFn) -> Position {
+        let mut p = pos;
+        for _ in 0..n { p = step(self, p); }
+        p
+    }
+}
+
+fn step(map: &Map, position: Position) -> Position {
+    let imax = map.tiles.len();
+    let jmax = map.tiles[0].len();
+    let s = position.d.step();
+    let mut p = position;
+    loop {
+        let inext = ((s.0 + imax as i64) as usize + p.i) % imax;
+        let jnext = ((s.1 + jmax as i64) as usize + p.j) % jmax;
+        p = Position { i: inext, j: jnext, d: p.d };
+        match map.tiles[p.i][p.j] {
+            Tile::Walk => return p,
+            Tile::Wall => return position,
+            Tile::Skip => ()
+        }
+    }
+}
+
+fn password(p: Position) -> usize {
+    1000 * (p.i+1) + 4 * (p.j+1) + p.d.value()
+}
+
+fn main() {
+    let map = Map::from_stdin();
+    let (turns, steps) = read_instruction_line_from_stdin();
+    let mut position = map.start_position();
+
+    for i in 0..turns.len() {
+        position = map.walk(position, steps[i], step);
+        position.d = position.d.turn(turns[i]);
+    }
+    position = map.walk(position, steps[steps.len()-1], step);
+    println!("{}", password(position));
+}
diff --git a/2022/22/b.rs b/2022/22/b.rs
new file mode 100644
index 0000000..1d292ee
--- /dev/null
+++ b/2022/22/b.rs
@@ -0,0 +1,314 @@
+use std::mem::swap;
+mod common;
+use common::*;
+
+// Use 4 for the test input, 50 for the real one
+//const CUBE_SIZE: usize = 4;
+const CUBE_SIZE: usize = 50;
+
+// Connections between faces to make the cube 3D.
+// This is hard coded to work for my specific input.
+// To make it work for a different input you have to change this.
+// The faces are in top-to-bottom, left-to-right order of input.
+// For each face, the 4 connections are in order right, down, left, up.
+
+// Test case. Configuration:
+//   0     U = 0, D = 4
+// 123     R = 5, L = 2
+//   45    F = 3, B = 1
+/*
+const CONNECTIONS: [[Connection; 4]; 6] = [
+    // Face 0 = U
+    [
+        Connection { face: 5, side: Direction::Right },
+        Connection { face: 3, side: Direction::Up },
+        Connection { face: 2, side: Direction::Up },
+        Connection { face: 1, side: Direction::Up },
+    ],
+
+    // Face 1
+    [
+        Connection { face: 2, side: Direction::Left },
+        Connection { face: 4, side: Direction::Down },
+        Connection { face: 5, side: Direction::Down },
+        Connection { face: 0, side: Direction::Up },
+    ],
+
+    // Face 2
+    [
+        Connection { face: 3, side: Direction::Left },
+        Connection { face: 4, side: Direction::Left },
+        Connection { face: 1, side: Direction::Right },
+        Connection { face: 0, side: Direction::Left },
+    ],
+
+    // Face 3
+    [
+        Connection { face: 5, side: Direction::Up },
+        Connection { face: 4, side: Direction::Up },
+        Connection { face: 2, side: Direction::Right },
+        Connection { face: 0, side: Direction::Down },
+    ],
+
+    // Face 4
+    [
+        Connection { face: 5, side: Direction::Left },
+        Connection { face: 1, side: Direction::Down },
+        Connection { face: 2, side: Direction::Down },
+        Connection { face: 3, side: Direction::Down },
+    ],
+
+    // Face 5
+    [
+        Connection { face: 0, side: Direction::Right },
+        Connection { face: 1, side: Direction::Left },
+        Connection { face: 4, side: Direction::Right },
+        Connection { face: 3, side: Direction::Right },
+    ],
+];
+*/
+
+// Input. Configuration:
+//  01
+//  2 
+// 34
+// 5
+const CONNECTIONS: [[Connection; 4]; 6] = [
+    // Face 0 = U
+    [
+        Connection { face: 1, side: Direction::Left },
+        Connection { face: 2, side: Direction::Up },
+        Connection { face: 3, side: Direction::Left },
+        Connection { face: 5, side: Direction::Left },
+    ],
+
+    // Face 1
+    [
+        Connection { face: 4, side: Direction::Right },
+        Connection { face: 2, side: Direction::Right },
+        Connection { face: 0, side: Direction::Right },
+        Connection { face: 5, side: Direction::Down },
+    ],
+
+    // Face 2
+    [
+        Connection { face: 1, side: Direction::Down },
+        Connection { face: 4, side: Direction::Up },
+        Connection { face: 3, side: Direction::Up },
+        Connection { face: 0, side: Direction::Down },
+    ],
+
+    // Face 3
+    [
+        Connection { face: 4, side: Direction::Left },
+        Connection { face: 5, side: Direction::Up },
+        Connection { face: 0, side: Direction::Left },
+        Connection { face: 2, side: Direction::Left },
+    ],
+
+    // Face 4
+    [
+        Connection { face: 1, side: Direction::Right },
+        Connection { face: 5, side: Direction::Right },
+        Connection { face: 3, side: Direction::Right },
+        Connection { face: 2, side: Direction::Down },
+    ],
+
+    // Face 5
+    [
+        Connection { face: 4, side: Direction::Down },
+        Connection { face: 1, side: Direction::Up },
+        Connection { face: 0, side: Direction::Up },
+        Connection { face: 3, side: Direction::Down },
+    ],
+];
+
+
+#[derive(Copy, Clone, Debug)]
+struct Connection {
+    pub face: usize,
+    pub side: Direction
+}
+
+struct Face {
+    pub tiles: [[Tile; CUBE_SIZE]; CUBE_SIZE],
+    offset_i: usize,
+    offset_j: usize
+}
+
+#[derive(PartialEq, Debug, Copy, Clone)]
+struct Position {
+    f: usize,
+    i: usize,
+    j: usize,
+    d: Direction
+}
+
+#[allow(dead_code)]
+impl Face {
+    pub fn empty() -> Face {
+        Face {
+            tiles: [[Tile::Skip; CUBE_SIZE]; CUBE_SIZE],
+            offset_i: 0,
+            offset_j: 0
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.tiles[0][0] == Tile::Skip
+    }
+
+    pub fn print(&self) {
+        for i in 0..CUBE_SIZE {
+            for j in 0..CUBE_SIZE {
+                print!("{}", self.tiles[i][j].to_char());
+            }
+            println!();
+        }
+    }
+}
+
+struct Cube {
+    pub faces: Vec<Face>
+}
+
+type StepFn = fn(&Cube, Position) -> Position;
+
+impl Cube {
+    pub fn from_stdin() -> Cube {
+        let mut faces = vec![];
+        let mut line = String::new();
+        let mut offset_i = 0;
+        while faces.len() < 6 {
+            let mut row = [Face::empty(), Face::empty(), Face::empty(),
+                           Face::empty(), Face::empty(), Face::empty()];
+            for k in 0..CUBE_SIZE {
+                let _ = std::io::stdin().read_line(&mut line);
+                let bytes = &line.as_bytes();
+                for l in 0..line.len()-1 {
+                    row[l / CUBE_SIZE].tiles[k][l % CUBE_SIZE] =
+                        Tile::from_byte(bytes[l]);
+                }
+                line.clear();
+            }
+            let mut offset_j = 0;
+            for mut r in row {
+                r.offset_i = offset_i;
+                r.offset_j = offset_j;
+                if !r.is_empty() {
+                    faces.push(r);
+                }
+                offset_j += CUBE_SIZE;
+            }
+            offset_i += CUBE_SIZE;
+        }
+        let _ = std::io::stdin().read_line(&mut line); // Read empty line
+        assert!(faces.len() == 6, "Cube has {} faces", faces.len());
+        Cube { faces }
+    }
+
+    fn start_position(&self) -> Position {
+        let j = self.faces[0].tiles[0].iter()
+            .position(|t| *t == Tile::Walk).unwrap();
+        Position { f: 0, i: 0, j, d: Direction::Right }
+    }
+
+    pub fn walk(&self, pos: Position, n: usize, step: StepFn) -> Position {
+        let mut p = pos;
+        for _ in 0..n { p = step(self, p); }
+        p
+    }
+}
+
+fn flips(d1: Direction, d2: Direction) -> bool {
+    match d1 {
+        Direction::Right | Direction::Up =>
+            d2 == Direction::Right || d2 == Direction::Up,
+        Direction::Down | Direction::Left =>
+            d2 == Direction::Down || d2 == Direction::Left
+    }
+}
+
+fn swaps(d1: Direction, d2: Direction) -> bool {
+    match d1 {
+        Direction::Right | Direction::Left =>
+            d2 == Direction::Up || d2 == Direction::Down,
+        Direction::Up | Direction::Down =>
+            d2 == Direction::Right || d2 == Direction::Left
+    }
+}
+
+fn validate_connections(conn: &[[Connection; 4]; 6]) {
+    for i in 0..6 {
+        for j in 0..4 {
+            let c = conn[i][j];
+            let d = conn[c.face][c.side.value()];
+            assert!(d.face == i, "Bad connection: face {}-{}", i, j);
+            assert!(d.side.value() == j, "Bad connection: side {}-{}", i, j);
+        }
+    }
+}
+
+fn overflow(i: i64, j: i64) -> Option<Direction> {
+    if i == -1 { return Some(Direction::Up) }
+    if j == -1 { return Some(Direction::Left) }
+    if i as usize == CUBE_SIZE { return Some(Direction::Down) }
+    if j as usize == CUBE_SIZE { return Some(Direction::Right) }
+    None
+}
+
+fn on_other_side(i: i64, flip: bool, positive: bool) -> usize {
+    const CUBE_SIZE_I64: i64 = CUBE_SIZE as i64;
+    (if i >= 0 && i < CUBE_SIZE_I64 {
+        if flip { CUBE_SIZE_I64 - i - 1 } else { i }
+    } else {
+        if positive { 0 } else { CUBE_SIZE_I64 - 1 }
+    }) as usize
+}
+
+fn step(cube: &Cube, p: Position) -> Position {
+    let s = p.d.step();
+    let mut inext = s.0 + p.i as i64;
+    let mut jnext = s.1 + p.j as i64;
+
+    let ret = if let Some(d) = overflow(inext, jnext) {
+        let conn = CONNECTIONS[p.f][d.value()];
+        let flip = flips(p.d, conn.side);
+        let new_direction = conn.side.opposite();
+        let positive = new_direction.is_positive();
+        if swaps(p.d, conn.side) { swap(&mut inext, &mut jnext) }
+        Position {
+            f: conn.face,
+            i: on_other_side(inext, flip, positive),
+            j: on_other_side(jnext, flip, positive),
+            d: conn.side.opposite()
+        }
+    } else {
+        Position {
+            f: p.f,
+            i: inext as usize,
+            j: jnext as usize,
+            d: p.d
+        }
+    };
+
+    if cube.faces[ret.f].tiles[ret.i][ret.j] == Tile::Wall { p } else { ret }
+}
+
+fn password(cube: &Cube, p: Position) -> usize {
+    let f = &cube.faces[p.f];
+    1000 * (p.i + f.offset_i + 1) + 4 * (p.j + f.offset_j + 1) + p.d.value()
+}
+
+fn main() {
+    validate_connections(&CONNECTIONS);
+    let cube = Cube::from_stdin();
+    let mut position = cube.start_position();
+    let (turns, steps) = read_instruction_line_from_stdin();
+    for i in 0..turns.len() {
+        position = cube.walk(position, steps[i], step);
+        position.d = position.d.turn(turns[i]);
+    }
+    position = cube.walk(position, steps[steps.len()-1], step);
+    println!("{}", password(&cube, position));
+}
diff --git a/2022/22/common.rs b/2022/22/common.rs
new file mode 100644
index 0000000..881513c
--- /dev/null
+++ b/2022/22/common.rs
@@ -0,0 +1,111 @@
+use std::cmp::*;
+
+#[derive(PartialEq, Copy, Clone, Debug)]
+pub enum Tile { Walk, Wall, Skip }
+
+#[allow(dead_code)]
+impl Tile {
+    pub fn from_byte(b: u8) -> Tile {
+        match b {
+            b'.' => Tile::Walk,
+            b'#' => Tile::Wall,
+            b' ' => Tile::Skip,
+            _ => panic!("not a valid tile {}", b)
+        }
+    }
+
+    pub fn to_char(&self) -> char {
+        match self {
+            Tile::Walk => '.',
+            Tile::Wall => '#',
+            Tile::Skip => ' '
+        }
+    }
+}
+
+#[derive(PartialEq, Copy, Clone, Debug)]
+pub enum Direction { Up, Down, Right, Left }
+
+#[allow(dead_code)]
+impl Direction {
+    pub fn from_char(c: char) -> Direction {
+        match c {
+            'U' => Direction::Up,
+            'D' => Direction::Down,
+            'R' => Direction::Right,
+            'L' => Direction::Left,
+            _ => panic!("invalid char for direction")
+        }
+    }
+
+    pub fn turn(&self, t: Direction) -> Direction {
+        match t {
+            Direction::Right => match self {
+                Direction::Up => Direction::Right,
+                Direction::Right => Direction::Down,
+                Direction::Down => Direction::Left,
+                Direction::Left => Direction::Up
+            },
+            Direction::Left => match self {
+                Direction::Up => Direction::Left,
+                Direction::Left => Direction::Down,
+                Direction::Down => Direction::Right,
+                Direction::Right => Direction::Up
+            }
+            _ => panic!("cannot turn up or down")
+        }
+    }
+
+    pub fn step(&self) -> (i64, i64) {
+        match self {
+            Direction::Up => (-1, 0),
+            Direction::Down => (1, 0),
+            Direction::Right => (0, 1),
+            Direction::Left => (0, -1)
+        }
+    }
+
+    pub fn value(&self) -> usize {
+        match self {
+            Direction::Right => 0,
+            Direction::Down => 1,
+            Direction::Left => 2,
+            Direction::Up => 3
+        }
+    }
+
+    pub fn opposite(&self) -> Direction {
+        match self {
+            Direction::Right => Direction::Left,
+            Direction::Left => Direction::Right,
+            Direction::Up => Direction::Down,
+            Direction::Down => Direction::Up
+        }
+    }
+
+    pub fn is_positive(&self) -> bool {
+        *self == Direction::Down || *self == Direction::Right
+    }
+}
+
+pub fn read_instruction_line_from_stdin() -> (Vec<Direction>, Vec<usize>) {
+    let mut dir = vec![];
+    let mut step = vec![];
+    let mut line = String::new();
+    let _ = std::io::stdin().read_line(&mut line);
+    let mut i = 0;
+    while i < line.len()-1 {
+        match line.chars().nth(i).unwrap() {
+            '0'..='9' => {
+                let j = line[i..].find(|c: char| !c.is_digit(10)).unwrap() + i;
+                step.push(line[i..j].parse::<usize>().unwrap());
+                i = j;
+            },
+            c => {
+                dir.push(Direction::from_char(c));
+                i += 1;
+            }
+        }
+    }
+    (dir, step)
+}