add pathfinding crate and day 17 solution

2023/Cargo.lock

@@ -62,6 +62,7 @@ dependencies = [
  "aoc-runner",
  "aoc-runner-derive",
  "num",
+ "pathfinding",
 ]
 
 [[package]]
@@ -70,6 +71,55 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
+[[package]]
+name = "deprecate-until"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a3767f826efbbe5a5ae093920b58b43b01734202be697e1354914e862e8e704"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "semver",
+ "syn 2.0.39",
+]
+
+[[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
+[[package]]
+name = "fixedbitset"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
+
+[[package]]
+name = "hashbrown"
+version = "0.14.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "290f1a1d9242c78d09ce40a5e87e7554ee637af1351968159f4952f028f75604"
+
+[[package]]
+name = "indexmap"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d530e1a18b1cb4c484e6e34556a0d948706958449fca0cab753d649f2bce3d1f"
+dependencies = [
+ "equivalent",
+ "hashbrown",
+]
+
+[[package]]
+name = "integer-sqrt"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "276ec31bcb4a9ee45f58bec6f9ec700ae4cf4f4f8f2fa7e06cb406bd5ffdd770"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.9"
@@ -164,6 +214,21 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "pathfinding"
+version = "4.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6f4a3f5089b981000cb50ec24320faf7a19649a45e8730e4adf49f78f066528"
+dependencies = [
+ "deprecate-until",
+ "fixedbitset",
+ "indexmap",
+ "integer-sqrt",
+ "num-traits",
+ "rustc-hash",
+ "thiserror",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.70"
@@ -211,12 +276,24 @@ version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c08c74e62047bb2de4ff487b251e4a92e24f48745648451635cec7d591162d9f"
 
+[[package]]
+name = "rustc-hash"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
+
 [[package]]
 name = "ryu"
 version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ad4cc8da4ef723ed60bced201181d83791ad433213d8c24efffda1eec85d741"
 
+[[package]]
+name = "semver"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "836fa6a3e1e547f9a2c4040802ec865b5d85f4014efe00555d7090a3dcaa1090"
+
 [[package]]
 name = "serde"
 version = "1.0.193"
@@ -272,18 +349,18 @@ dependencies = [
 
 [[package]]
 name = "thiserror"
-version = "1.0.50"
+version = "1.0.52"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f9a7210f5c9a7156bb50aa36aed4c95afb51df0df00713949448cf9e97d382d2"
+checksum = "83a48fd946b02c0a526b2e9481c8e2a17755e47039164a86c4070446e3a4614d"
 dependencies = [
  "thiserror-impl",
 ]
 
 [[package]]
 name = "thiserror-impl"
-version = "1.0.50"
+version = "1.0.52"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "266b2e40bc00e5a6c09c3584011e08b06f123c00362c92b975ba9843aaaa14b8"
+checksum = "e7fbe9b594d6568a6a1443250a7e67d80b74e1e96f6d1715e1e21cc1888291d3"
 dependencies = [
  "proc-macro2",
  "quote",

2023/Cargo.toml

@@ -12,6 +12,7 @@ aoc-runner = "0.3.0"
 aoc-runner-derive = "0.3.0"
 aoc-parse = "0.2.17"
 num = "0.4"
+pathfinding = "4.8.0"
 
 [profile.release]
 incremental = true

2023/src/day17.rs

@@ -0,0 +1,135 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+use pathfinding::matrix::{directions, Matrix};
+use pathfinding::prelude::astar;
+
+#[aoc_generator(day17)]
+fn parse(input: &str) -> Matrix<usize> {
+    input
+        .lines()
+        .filter_map(|line| {
+            if !line.is_empty() {
+                Some(
+                    line.chars()
+                        .map(|c| c.to_digit(10).expect("bad digit") as usize),
+                )
+            } else {
+                None
+            }
+        })
+        .collect::<Matrix<usize>>()
+}
+
+#[derive(Clone, Eq, Hash, PartialEq, Ord, PartialOrd)]
+struct Path {
+    position: (usize, usize),
+    dir: (isize, isize),
+    steps: usize,
+}
+
+fn distance(s: &(usize, usize), d: &(usize, usize)) -> usize {
+    s.0.abs_diff(d.0) + s.1.abs_diff(d.1)
+}
+
+fn find_path<const MIN: usize, const MAX: usize>(map: &Matrix<usize>) -> usize {
+    let start = Path {
+        position: (0, 0),
+        dir: (0, 0),
+        steps: 0,
+    };
+    let dest = (map.rows - 1, map.columns - 1);
+
+    let path = astar(
+        &start,
+        |cur| match cur.steps >= MIN || (cur.dir.0 == 0 && cur.dir.1 == 0) {
+            true => find_successors::<MAX>(map, cur),
+            false => continue_in_direction::<MIN>(map, cur),
+        },
+        |cur| distance(&dest, &cur.position),
+        |cur| cur.position == dest && cur.steps >= MIN,
+    )
+    .expect("path is missing");
+    path.1
+}
+
+fn find_successors<const MAX: usize>(map: &Matrix<usize>, p: &Path) -> Vec<(Path, usize)> {
+    [directions::N, directions::E, directions::S, directions::W]
+        .iter()
+        .flat_map(|dir| {
+            map.move_in_direction(p.position, *dir)
+                .map(|cur| (cur, *dir, *map.get(cur).unwrap()))
+        })
+        .filter(|(cur, dir, _weight)| {
+            let backwards = p.dir.0 == -dir.0 && p.dir.1 == -dir.1;
+            !backwards && *cur != (0, 0)
+        })
+        .flat_map(|(cur, dir, weight)| {
+            let steps = match p.dir == dir {
+                true => p.steps + 1,
+                false => 1,
+            };
+
+            match steps <= MAX {
+                true => {
+                    let next = Path {
+                        position: cur,
+                        dir,
+                        steps,
+                    };
+                    Some((next, weight))
+                }
+                false => None,
+            }
+        })
+        .collect::<Vec<_>>()
+}
+
+fn continue_in_direction<const MIN: usize>(map: &Matrix<usize>, p: &Path) -> Vec<(Path, usize)> {
+    match map.move_in_direction(p.position, p.dir) {
+        Some(point) => {
+            let heat = *map.get(point).unwrap();
+            let new_path = Path {
+                position: point,
+                dir: p.dir,
+                steps: p.steps + 1,
+            };
+            vec![(new_path, heat)]
+        }
+        None => Vec::with_capacity(0),
+    }
+}
+
+#[aoc(day17, part1)]
+fn part1(input: &Matrix<usize>) -> usize {
+    find_path::<1, 3>(&input)
+}
+
+#[aoc(day17, part2)]
+fn part2(input: &Matrix<usize>) -> usize {
+    find_path::<4, 10>(&input)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const SAMPLE_DATA: &'static str = r#"2413432311323
+3215453535623
+3255245654254
+3446585845452
+4546657867536
+1438598798454
+4457876987766
+3637877979653
+4654967986887
+4564679986453
+1224686865563
+2546548887735
+4322674655533
+"#;
+
+    #[test]
+    fn sample_data() {
+        let input = parse(&SAMPLE_DATA);
+        assert_eq!(part1(&input), 102);
+    }
+}

2023/src/lib.rs

@@ -16,5 +16,6 @@ mod day13;
 mod day14;
 mod day15;
 mod day16;
+mod day17;
 
 aoc_lib! { year = 2023 }