day 12

inputs/day12.txt

@@ -0,0 +1,41 @@
+abaaacccccccccaaaaaaccccccccccccccccaacccccccccccaacaaaaaaaaaaaaaaaaaccaaaaacccaaaaccccccccccccccccccccccccccccccccccccccccccccccccccccccccaaaaa
+abaaacccccccccaaaaaacccccccccccccccaaaaccccccccccaaaaaaaacaaaaaaaaaaaccaaaaaaccaaaacccccccccccccccccccccccccccccccccccccccccccccccccccccccaaaaaa
+abaaaccccccccccaaaaacccccccccccccccaaaacccccccccccaaaaacccaaaaaaaaaacccaaaaaacccaaccccccccccccccaaaaacccccccccccccccccccccccccccccccccccccaaaaaa
+abccccaaccccccaaaaacccccccccaaaaaccaaaaccccccccccccaaaaacaaaaaaaaacccccaaaaaccccccccccccccccccccaaaaacccccccccccccccccaaaccccaaaccccccccccaaacaa
+abcccaaaacccccaaaaacccccccccaaaaacccccccccccccccccaaacaaaaaaaaaacccccccaaaaacccccccccccccccccccaaaaaacccccccccccccccccaaaaccaaaaccccccccccccccaa
+abcccaaaaacacccccccccccccccaaaaaaccccccccccccccccccaaccaaaaacaaaaccccccccccccccccccccccccccccccaaaaaaccccccccccccccccccaaaaaaaacccccccccccccccaa
+abaaaaaaaaaacccccccccccccccaaaaaaccccccccccccccccccccccaaaacccaaaccccccccccccccccccccccccccccccaaaaaacccccccccccccccciiiiijaaaaccccccccccccccccc
+abaaaaaaaaaacccccccccccccccaaaaaacccccccccccccccccccccccccccccaaacccccccccccccccccccccccccccccccaaaccccccccccccccccciiiiiijjjaccccccccaaaccccccc
+abccaaaaaaccccccccccccccccccaaaccccccccccccccccccccccccccccccccacccccccccccaacccccccccccccccccccccccccccccccccccccciiiiioijjjjaaccccccaaaaaacccc
+abccaaaaaacccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccaaaaaacccccccccccccccccccccccccccccccccccciiinnooojjjjjaaccaaaaaaaacccc
+abccaaaaaacccccccccccccccccccccccccccccccccccccaacccccaacccccccccccccccccaaaaaacccccccccccccccccccccccccccaaaccccciiinnnoooojjjjjjkkkaaaaaaacccc
+abcaaaaaaaaccccccccccccccccccccccccccccccccccccaaaccaaaaaaccccaaacccccccccaaaacccccccccccccccccccccccccccccaaaaccciiinnnouooojjjjkkkkkaaaaaccccc
+abccaccccccccccccccccccaaccccccaccccccccccccaaaaaaaaaaaaaacccaaaacccccccccaaaacccccccccccccccccccccccccccaaaaaacchhinnnttuuooooookkkkkkkaaaccccc
+abccccccccccccccccccaacaaaccccaaaaaaaaccccccaaaaaaaacaaaaacccaaaacccccccccaccacccccccccccccccccccccccccccaaaaacchhhhnntttuuuooooppppkkkkcaaacccc
+abccccccccaaacccccccaaaaaccccccaaaaaaccccccccaaaaaacaaaaaccccaaaaccccccccccccccccccccccccccccaccccccccccccaaaaahhhhnnntttxuuuooppppppkkkcccccccc
+abccccccccaaaacccccccaaaaaaccccaaaaaaccaaacccaaaaaacaaaaaccccccccccccccaaccccccccccccccaaaaaaaacccccccccccaachhhhhnnnntttxxuuuuuuuupppkkkccccccc
+abccccccccaaaacccccaaaaaaaacccaaaaaaaacaaacacaaaaaaccccccccccccccccccccaacccccccccccccccaaaaaacccccccccccccchhhhmnnnntttxxxxuuuuuuupppkkcccccccc
+abacccccccaaaacccccaaaaacaaccaaaaaaaaaaaaaaaaaaccaacccccccccccccccccaaaaaaaaccccccccccccaaaaaaccccccccccccchhhhmmmntttttxxxxuyyyuvvpppklcccccccc
+abacccccccccccccccccacaaaccaaaaaaaaaaaaaaaaaaaccccccccccccccccccccccaaaaaaaacccccccccccaaaaaaaaccccccccccccgghmmmtttttxxxxxxyyyyvvvpplllcccccccc
+abaccccccccaacccccccccaaaccaaaaaaaacaaaaaaaaaaccccccccccccccccccccccccaaaaccccccccccccaaaaaaaaaaccccccaccccgggmmmtttxxxxxxxyyyyyvvppplllcccccccc
+SbaaaccccccaaacaaaccccccccaaaaaaaaacaaaaaaaaacccccccccccccccccccccccccaaaaacccccccccccaaaaaaaaaaaaacaaaccaagggmmmtttxxxEzzzzyyyvvppplllccccccccc
+abaacccccccaaaaaaacccccccaaaaaaacaaccaaaaaaaccccccccccccccaaaccccccccaaaaaacccccccccccacacaaacccaaaaaaacaaagggmmmsssxxxxxyyyyyvvvqqqlllccccccccc
+abaccccccccaaaaaaccacccaaaaaaaaacccccccaaaaaaccccccccccccaaaaccccccccaaccaacccccccccccccccaaaccccaaaaaaccaagggmmmssssxxwwyyyyyyvvqqqlllccccccccc
+abaccccccaaaaaaaaccaacaaaccaaaaaacccccaaaaaaaccccccccccccaaaaccccccccccaacccccccccccccccccaacccccaaaaaaaaaaggggmmmssssswwyywyyyyvvqqlllccccccccc
+abaccccccaaaaaaaaacaaaaacccaaaaaacccccaaacaaaccccccccccccaaaaccccccccaaaaaaccccccccccccaacccccccaaaaaaaaaaaaggggmmmossswwyywwyyvvvqqqllccccccccc
+abcccccccaaaaaaaaaacaaaaaacaaccccccccaaacccccccccccccccccccccccccccccaaaaaaccccccccccccaaaaacccaaaaaaaaaaaaaaggggoooosswwywwwwvvvvqqqmlccccccccc
+abccccccccccaaacaaaaaaaaaacccccccccccaaacaccccccccccccccccccccccccccccaaaaccccccccccccaaaaaccccaaacaaacccaaacagggfooosswwwwwrvvvvqqqqmmccccccccc
+abccccccccccaaacccaaaaaaaacccccccccaacaaaaacccccccccccccccccccccccccccaaaaccccccccccccaaaaaacccccccaaacccaaccccfffooosswwwwrrrrrqqqqqmmccccccccc
+abccccccccccaacccccccaaccccccccccccaaaaaaaacccccccccccccaaccccccccccccaccaccccccccccccccaaaacccccccaacccccccccccfffoossrwrrrrrrrqqqqmmmccccccccc
+abccaaaccccccccccccccaacccccccccccccaaaaaccccccccccccaacaacccccccaaaaacccccccccccccccccaacccccccccccccccccccccccfffoossrrrrrnnnmqqmmmmmccccccccc
+abcaaaaccccccccccccccccccccccccccccccaaaaacccccccccccaaaaacccccccaaaaacccaaaccccccccccccccccccccccccccccccccccccfffooorrrrrnnnnmmmmmmmccccaacccc
+abcaaaacccccccccccccccccccccccccccccaaacaaccccacccccccaaaaaaccccaaaaaaccccaaaccacccccccccccccccccccccccccccccccccffoooonnnnnnnnmmmmmmccccaaacccc
+abccaaacccccccccccccccccccccaaaaaccccaaccccaaaacccccaaaaaaaaccccaaaaaaccccaaaaaaaccccccccccccccccaccaccccccccccccfffooonnnnnnddddddddcccaaaccccc
+abccccccccccccccccccccccccccaaaaaccccccccccaaaaaacccaaaaacaacccaaaaaaaccaaaaaaaacccccccccccccccccaaaaccccccccccccfffeonnnnneddddddddddcaaacccccc
+abccccccccccaaaccccccccccccaaaaaacccccccccccaaaacccccacaaacccccaacaacccaaaaaaaaacccccccccccccccccaaaacccccccccccccffeeeeeeeeddddddddcccaaacccccc
+abcccccccccaaaaccccacccccccaaaaaaccccccccccaaaaacccccccaaaacccaaacaccccaaaaaaaaaccccccccccccccccaaaaaaccccccccccccceeeeeeeeedacccccccccccccccccc
+abaccccccccaaaaccccaaacaaacaaaaaaccccccccccaacaaccccccccaaaacaaaacaaacaaaaaaaaaacccccccccccccaacaaaaaacccccccccccccceeeeeeeaaacccccccccccccccaaa
+abaaacccccccaaaccccaaaaaaaccaaaccccccccaaacccccccccccccccaaaaaaaacaaaaaaaaaaaaaaacacaaccaaacaaacccaacccccccccccccccccaacccaaaacccccccccccccccaaa
+abaaaccccccccccccccaaaaaaccccccccccccccaaacccccccccccccccaaaaaaaccaaaaaaccaacccaccaaaaccaaaaaaaccccccccaaccccccccccccccccccaaacccccccccccccccaaa
+abaaccccccccccccccaaaaaaacccccccccccaaaaaaaaccccccccccccccaaaaaaaaaaaaaacaaaccccccaaaaaccaaaaaaccccccaaaaccccccccccccccccccaaaccccccccccccaaaaaa
+abaaaccccccccccccaaaaaaaaaacccccccccaaaaaaaacccccccccccaaaaaaaaaaaaaaaaaaacccccccaaaaaacaaaaaaaaaccccaaaaaacccccccccccccccccccccccccccccccaaaaaa

src/bin/day12_1.rs

@@ -0,0 +1,8 @@
+use std::fs;
+
+use aoc2022::day12::process_part_1;
+
+fn main() {
+    let file = fs::read_to_string("./inputs/day12.txt").unwrap();
+    println!("{}", process_part_1(&file));
+}

src/bin/day12_2.rs

@@ -0,0 +1,8 @@
+use std::fs;
+
+use aoc2022::day12::process_part_2;
+
+fn main() {
+    let file = fs::read_to_string("./inputs/day12.txt").unwrap();
+    println!("{}", process_part_2(&file));
+}

src/day12.rs

@@ -0,0 +1,118 @@
+use std::collections::{HashSet, VecDeque};
+
+type Coord = (usize, usize);
+type Map = Vec<Vec<i8>>;
+
+// ah yes, Breadth First Search
+pub fn process_part_1(input: &str) -> u32 {
+    let (start, target, map) = parse_input(input);
+    let mut queue = VecDeque::from([(start, map[start.1][start.0], 0)]);
+    let mut visited = HashSet::from([start]);
+
+    while !queue.is_empty() {
+        let (pos, elevation, steps) = queue.pop_front().unwrap();
+        if pos == target {
+            return steps;
+        }
+
+        for (neighbor, neighbor_elevation) in neighbors(&map, pos) {
+            if neighbor_elevation - elevation <= 1 && !visited.contains(&neighbor) {
+                queue.push_back((neighbor, neighbor_elevation, steps + 1));
+                visited.insert(neighbor);
+            }
+        }
+    }
+
+    panic!("no path");
+}
+
+pub fn process_part_2(input: &str) -> u32 {
+    let (_, target, map) = parse_input(input);
+    let mut queue = VecDeque::from([(target, map[target.1][target.0], 0)]);
+    let mut visited = HashSet::from([target]);
+
+    while !queue.is_empty() {
+        let (pos, elevation, steps) = queue.pop_front().unwrap();
+        if elevation == 0 {
+            return steps;
+        }
+
+        for (neighbor, neighbor_elevation) in neighbors(&map, pos) {
+            if elevation - neighbor_elevation <= 1 && !visited.contains(&neighbor) {
+                queue.push_back((neighbor, neighbor_elevation, steps + 1));
+                visited.insert(neighbor);
+            }
+        }
+    }
+
+    panic!("no path");
+}
+
+pub fn parse_input(input: &str) -> (Coord, Coord, Map) {
+    let mut start = (0, 0);
+    let mut end = (0, 0);
+    let map = input
+        .lines()
+        .enumerate()
+        .map(|(y, line)| {
+            line.chars()
+                .enumerate()
+                .map(|(x, c)| match c {
+                    'S' => {
+                        start = (x, y);
+                        'a'
+                    }
+                    'E' => {
+                        end = (x, y);
+                        'z'
+                    }
+                    _ => c,
+                })
+                .map(char_to_int)
+                .collect()
+        })
+        .collect();
+    (start, end, map)
+}
+
+// data only contains a-z, S and E
+// this one only deals with a-z
+pub fn char_to_int(c: char) -> i8 {
+    (c as i16 - 'a' as i16) as i8
+}
+
+pub fn neighbors(map: &Map, pos: Coord) -> Vec<(Coord, i8)> {
+    [(-1, 0), (1, 0), (0, -1), (0, 1)]
+        .into_iter()
+        .flat_map(|(x, y)| {
+            // Haha wow, I simultaneously hate and love this
+            // Reminder to the reader that flat_map flattens Options as much as it can flatten Vec's
+            Some((
+                (pos.0.checked_add_signed(x)?),
+                (pos.1.checked_add_signed(y)?),
+            ))
+        })
+        .flat_map(|(x, y)| Some(((x, y), *map.get(y)?.get(x)?)))
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = "Sabqponm
+abcryxxl
+accszExk
+acctuvwj
+abdefghi";
+
+    #[test]
+    fn day1() {
+        assert_eq!(process_part_1(INPUT), 31);
+    }
+
+    #[test]
+    fn day2() {
+        assert_eq!(process_part_2(INPUT), 29);
+    }
+}

src/lib.rs

@@ -12,3 +12,4 @@ pub mod day08;
 pub mod day09;
 pub mod day10;
 pub mod day11;
+pub mod day12;