Day 10 part 1

2024/rust/src/day10.rs

@@ -0,0 +1,78 @@
+mod prelude;
+pub use crate::prelude::*;
+
+fn main() {
+    let input = day_input(10);
+    show_answers(part1(&input), part2(&input));
+}
+
+fn part1(input: &str) -> usize {
+    println!("{input}");
+    let mut sum = 0;
+    let map: Vec<Vec<u8>> = input
+        .lines()
+        .map(|l| l.bytes().map(|b| b - b'0').collect())
+        .collect();
+    for (y, row) in map.iter().enumerate() {
+        for (x, height) in row.iter().enumerate() {
+            let mut scores = HashSet::new();
+            if *height == 0 {
+                find_paths_to_nines(&map, *height, x, y, &mut scores);
+                sum += scores.len();
+            }
+            println!("{x} {y} {height}");
+        }
+    }
+    sum
+}
+
+fn find_paths_to_nines(
+    map: &Vec<Vec<u8>>,
+    height: u8,
+    x: usize,
+    y: usize,
+    scores: &mut HashSet<(usize, usize)>,
+) {
+    if height == 9 {
+        scores.insert((x, y));
+        println!("found a 9");
+    }
+    for (nx, ny) in [
+        (x + 1, y),
+        (x.saturating_sub(1), y),
+        (x, y + 1),
+        (x, y.saturating_sub(1)),
+    ] {
+        if nx >= map[0].len() || ny >= map.len() {
+            continue;
+        }
+        let next_height = map[ny][nx];
+        if next_height.saturating_sub(height) == 1 {
+            println!("{height} -> {next_height} at {nx},{ny}");
+            find_paths_to_nines(map, next_height, nx, ny, scores)
+        }
+    }
+}
+
+fn part2(input: &str) -> usize {
+    0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = r#"89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732"#;
+        assert_eq!(part1(input), 36);
+        assert_eq!(part2(input), 0);
+    }
+}