1 files changed, 82 insertions, 0 deletions
diff --git a/src/bin/2022/day12.rs b/src/bin/2022/day12.rs
new file mode 100644
index 0000000..d2d0acf
--- /dev/null
+++ b/src/bin/2022/day12.rs
@@ -0,0 +1,82 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+
+use advent_of_code::prelude::*;
+
+pub struct Map {
+    grid: Grid<u8>,
+    start: (Row, Col),
+    end: (Row, Col),
+}
+
+impl advent_of_code::graph::Graph<(Row, Col), (Row, Col)> for Map {
+    type Edges = advent_of_code::grid::Adjacent;
+
+    fn edges(&self, v: (Row, Col)) -> Self::Edges {
+        self.grid.adjacent(v.0, v.1, false)
+    }
+
+    fn edge(&self, v: (Row, Col), e: (Row, Col)) -> ((Row, Col), u64) {
+        (
+            e,
+            if self.grid[e.0][e.1] <= self.grid[v.0][v.1] + 1 {
+                1
+            } else {
+                999_999_999
+            },
+        )
+    }
+}
+
+pub fn parse(fh: File) -> Result<Map> {
+    let mut start = None;
+    let mut end = None;
+    let grid = parse::grid(parse::raw_lines(fh), |c, row, col| match c {
+        b'a'..=b'z' => c - b'a',
+        b'S' => {
+            start = Some((row, col));
+            0
+        }
+        b'E' => {
+            end = Some((row, col));
+            b'z' - b'a'
+        }
+        _ => panic!("unknown map char '{c}'"),
+    });
+    Ok(Map {
+        grid,
+        start: start.expect("start not found"),
+        end: end.expect("end not found"),
+    })
+}
+
+pub fn part1(map: Map) -> Result<u64> {
+    Ok(map.dijkstra(map.start, map.end).0)
+}
+
+pub fn part2(map: Map) -> Result<u64> {
+    Ok(map
+        .grid
+        .indexed_cells()
+        .filter_map(|(pos, height)| {
+            if *height == 0 {
+                Some(map.dijkstra(pos, map.end).0)
+            } else {
+                None
+            }
+        })
+        .min()
+        .unwrap())
+}
+
+#[test]
+fn test() {
+    assert_eq!(
+        part1(parse(parse::data(2022, 12).unwrap()).unwrap()).unwrap(),
+        504
+    );
+    assert_eq!(
+        part2(parse(parse::data(2022, 12).unwrap()).unwrap()).unwrap(),
+        500
+    );
+}