day-23 done but could be optimized to quicken part 2

2023/day-23/src/part2.rs

@@ -0,0 +1,103 @@
+#![warn(clippy::all, clippy::pedantic)]
+
+use std::collections::HashMap;
+
+use glam::IVec2;
+use petgraph::{prelude::*, algo};
+
+
+#[derive(Debug, Copy, Clone)]
+enum PointType {
+    Any,
+    OnlyDown,
+    OnlyLeft,
+    OnlyRight,
+    OnlyUp,
+}
+
+impl PointType {
+    fn next_possibles(self) -> Vec<IVec2> {
+        match self {
+            _ => vec![IVec2::X, IVec2::Y, IVec2::NEG_X, IVec2::NEG_Y],
+        }
+    }
+}
+
+#[must_use]
+pub fn part2(input: &str) -> String {
+    let maze = parse_input(input);
+    //get the start position (assuming there is only one)
+    let start = *maze.keys().find(|pos| pos.y == 0).unwrap();
+    let end = maze.keys().fold(IVec2::splat(0), | max, current|  if max.y.max(current.y) == current.y { *current } else {max});
+    let mut maze_graph = DiGraph::<&PointType, u32>::new();
+    let node_map = maze.iter().map(|(pos, point_type)| (pos, maze_graph.add_node(point_type)) ).collect::<HashMap<_,_>>();
+
+    maze.iter().flat_map(|(pos, point_type)| {
+        point_type.next_possibles().iter().copied().filter_map(|dir| {
+            let next_pos = dir + *pos;
+            node_map.get(&next_pos).is_some().then(|| (node_map[pos], node_map[&next_pos], 1))
+        }).collect::<Vec<_>>()
+    })
+    .for_each(|(a, b, weight)| {
+        maze_graph.add_edge(a,b,weight);
+    });
+
+    (algo::all_simple_paths::<Vec<_>,_>(&maze_graph, node_map[&start], node_map[&end], 0, None).max_by(|a, b| a.len().cmp(&b.len())).unwrap().len() -1).to_string()
+}
+
+fn parse_input(input: &str) -> HashMap<IVec2, PointType> {
+    input
+        .lines()
+        .enumerate()
+        .flat_map(|(y, row)| {
+            row.chars().enumerate().filter_map(move |(x, c)| {
+                let pos = IVec2::new(i32::try_from(x).unwrap(), i32::try_from(y).unwrap());
+                match c {
+                    '.' => Some((pos, PointType::Any)),
+                    '>' => Some((pos, PointType::OnlyRight)),
+                    'v' => Some((pos, PointType::OnlyDown)),
+                    '^' => Some((pos, PointType::OnlyUp)),
+                    '<' => Some((pos, PointType::OnlyLeft)),
+                    _ => None,
+                }
+            })
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    const INPUT: &str = "#.#####################
+#.......#########...###
+#######.#########.#.###
+###.....#.>.>.###.#.###
+###v#####.#v#.###.#.###
+###.>...#.#.#.....#...#
+###v###.#.#.#########.#
+###...#.#.#.......#...#
+#####.#.#.#######.#.###
+#.....#.#.#.......#...#
+#.#####.#.#.#########v#
+#.#...#...#...###...>.#
+#.#.#v#######v###.###v#
+#...#.>.#...>.>.#.###.#
+#####v#.#.###v#.#.###.#
+#.....#...#...#.#.#...#
+#.#########.###.#.#.###
+#...###...#...#...#.###
+###.###.#.###v#####v###
+#...#...#.#.>.>.#.>.###
+#.###.###.#.###.#.#v###
+#.....###...###...#...#
+#####################.#";
+
+    #[test]
+    fn part2_works() {
+        let result = part2(INPUT);
+        assert_eq!(result, "154".to_string());
+    }
+}
+
+