AoC 2024 Day 20 - rust

README.md

@@ -10,7 +10,7 @@
 | ---| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
 | python3 | [✓](src/main/python/AoC2024_01.py) | [✓](src/main/python/AoC2024_02.py) | [✓](src/main/python/AoC2024_03.py) | [✓](src/main/python/AoC2024_04.py) | [✓](src/main/python/AoC2024_05.py) | [✓](src/main/python/AoC2024_06.py) | [✓](src/main/python/AoC2024_07.py) | [✓](src/main/python/AoC2024_08.py) | [✓](src/main/python/AoC2024_09.py) | [✓](src/main/python/AoC2024_10.py) | [✓](src/main/python/AoC2024_11.py) | [✓](src/main/python/AoC2024_12.py) | [✓](src/main/python/AoC2024_13.py) | [✓](src/main/python/AoC2024_14.py) | [✓](src/main/python/AoC2024_15.py) | [✓](src/main/python/AoC2024_16.py) | [✓](src/main/python/AoC2024_17.py) | [✓](src/main/python/AoC2024_18.py) | [✓](src/main/python/AoC2024_19.py) | [✓](src/main/python/AoC2024_20.py) | [✓](src/main/python/AoC2024_21.py) |  |  |  |  |
 | java | [✓](src/main/java/AoC2024_01.java) | [✓](src/main/java/AoC2024_02.java) | [✓](src/main/java/AoC2024_03.java) | [✓](src/main/java/AoC2024_04.java) | [✓](src/main/java/AoC2024_05.java) | [✓](src/main/java/AoC2024_06.java) | [✓](src/main/java/AoC2024_07.java) | [✓](src/main/java/AoC2024_08.java) |  | [✓](src/main/java/AoC2024_10.java) | [✓](src/main/java/AoC2024_11.java) | [✓](src/main/java/AoC2024_12.java) |  | [✓](src/main/java/AoC2024_14.java) | [✓](src/main/java/AoC2024_15.java) |  |  |  |  |  |  |  |  |  |  |
-| rust | [✓](src/main/rust/AoC2024_01/src/main.rs) | [✓](src/main/rust/AoC2024_02/src/main.rs) | [✓](src/main/rust/AoC2024_03/src/main.rs) | [✓](src/main/rust/AoC2024_04/src/main.rs) | [✓](src/main/rust/AoC2024_05/src/main.rs) | [✓](src/main/rust/AoC2024_06/src/main.rs) | [✓](src/main/rust/AoC2024_07/src/main.rs) | [✓](src/main/rust/AoC2024_08/src/main.rs) |  | [✓](src/main/rust/AoC2024_10/src/main.rs) | [✓](src/main/rust/AoC2024_11/src/main.rs) | [✓](src/main/rust/AoC2024_12/src/main.rs) | [✓](src/main/rust/AoC2024_13/src/main.rs) | [✓](src/main/rust/AoC2024_14/src/main.rs) | [✓](src/main/rust/AoC2024_15/src/main.rs) | [✓](src/main/rust/AoC2024_16/src/main.rs) | [✓](src/main/rust/AoC2024_17/src/main.rs) | [✓](src/main/rust/AoC2024_18/src/main.rs) | [✓](src/main/rust/AoC2024_19/src/main.rs) |  |  |  |  |  |  |
+| rust | [✓](src/main/rust/AoC2024_01/src/main.rs) | [✓](src/main/rust/AoC2024_02/src/main.rs) | [✓](src/main/rust/AoC2024_03/src/main.rs) | [✓](src/main/rust/AoC2024_04/src/main.rs) | [✓](src/main/rust/AoC2024_05/src/main.rs) | [✓](src/main/rust/AoC2024_06/src/main.rs) | [✓](src/main/rust/AoC2024_07/src/main.rs) | [✓](src/main/rust/AoC2024_08/src/main.rs) |  | [✓](src/main/rust/AoC2024_10/src/main.rs) | [✓](src/main/rust/AoC2024_11/src/main.rs) | [✓](src/main/rust/AoC2024_12/src/main.rs) | [✓](src/main/rust/AoC2024_13/src/main.rs) | [✓](src/main/rust/AoC2024_14/src/main.rs) | [✓](src/main/rust/AoC2024_15/src/main.rs) | [✓](src/main/rust/AoC2024_16/src/main.rs) | [✓](src/main/rust/AoC2024_17/src/main.rs) | [✓](src/main/rust/AoC2024_18/src/main.rs) | [✓](src/main/rust/AoC2024_19/src/main.rs) | [✓](src/main/rust/AoC2024_20/src/main.rs) |  |  |  |  |  |
 <!-- @END:ImplementationsTable:2024@ -->
 
 ## 2023

src/main/rust/AoC2024_20/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "AoC2024_20"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+aoc = { path = "../aoc" }

src/main/rust/AoC2024_20/src/main.rs

@@ -0,0 +1,106 @@
+#![allow(non_snake_case)]
+
+use aoc::graph::BFS;
+use aoc::grid::{CharGrid, Grid};
+use aoc::Puzzle;
+
+struct AoC2024_20;
+
+impl AoC2024_20 {
+    fn solve(&self, grid: &CharGrid, cheat_len: usize, target: usize) -> usize {
+        let start = grid.find_first_matching(|ch| ch == 'S').unwrap();
+        let distances = BFS::execute_full(
+            start,
+            |cell| grid.get(&cell) != '#',
+            |cell| {
+                grid.capital_neighbours(&cell)
+                    .into_iter()
+                    .filter(|n| grid.get(n) != '#')
+                    .collect()
+            },
+        );
+        let mut ans = 0;
+        for cell in distances.keys() {
+            for md in 2..cheat_len + 1 {
+                for n in cell.get_all_at_manhattan_distance(md) {
+                    if !distances.contains_key(&n) {
+                        continue;
+                    }
+                    if distances[&n] < distances[cell] {
+                        continue;
+                    }
+                    if distances[&n] - distances[cell] >= target + md {
+                        ans += 1;
+                    }
+                }
+            }
+        }
+        ans
+    }
+    fn sample_part_1(&self, grid: &CharGrid) -> usize {
+        self.solve(grid, 2, 2)
+    }
+
+    fn sample_part_2(&self, grid: &CharGrid) -> usize {
+        self.solve(grid, 20, 50)
+    }
+}
+
+impl aoc::Puzzle for AoC2024_20 {
+    type Input = CharGrid;
+    type Output1 = usize;
+    type Output2 = usize;
+
+    aoc::puzzle_year_day!(2024, 20);
+
+    fn parse_input(&self, lines: Vec<String>) -> Self::Input {
+        CharGrid::from(&lines.iter().map(AsRef::as_ref).collect::<Vec<_>>())
+    }
+
+    fn part_1(&self, grid: &Self::Input) -> Self::Output1 {
+        self.solve(grid, 2, 100)
+    }
+
+    fn part_2(&self, grid: &Self::Input) -> Self::Output2 {
+        self.solve(grid, 20, 100)
+    }
+
+    fn samples(&self) {
+        aoc::puzzle_samples! {
+            self, sample_part_1, TEST, 44,
+            self, sample_part_2, TEST, 285
+        };
+    }
+}
+
+fn main() {
+    AoC2024_20 {}.run(std::env::args());
+}
+
+const TEST: &str = "\
+###############
+#...#...#.....#
+#.#.#.#.#.###.#
+#S#...#.#.#...#
+#######.#.#.###
+#######.#.#...#
+#######.#.###.#
+###..E#...#...#
+###.#######.###
+#...###...#...#
+#.#####.#.###.#
+#.#...#.#.#...#
+#.#.#.#.#.#.###
+#...#...#...###
+###############
+";
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    pub fn samples() {
+        AoC2024_20 {}.samples();
+    }
+}

src/main/rust/aoc/src/graph.rs

@@ -63,6 +63,36 @@ where
         unreachable!();
     }
 
+    pub fn execute_full(
+        start: T,
+        is_end: impl Fn(T) -> bool,
+        adjacent: impl Fn(T) -> Vec<T>,
+    ) -> HashMap<T, usize> {
+        let mut q: VecDeque<State<T>> = VecDeque::new();
+        q.push_back(State {
+            node: start,
+            distance: 0,
+        });
+        let mut seen: HashSet<T> = HashSet::new();
+        seen.insert(start);
+        let mut distances: HashMap<T, usize> = HashMap::new();
+        while let Some(state) = q.pop_front() {
+            if is_end(state.node) {
+                distances.insert(state.node, state.distance);
+            }
+            adjacent(state.node).iter().for_each(|n| {
+                if !seen.contains(n) {
+                    seen.insert(*n);
+                    q.push_back(State {
+                        node: *n,
+                        distance: state.distance + 1,
+                    });
+                }
+            });
+        }
+        distances
+    }
+
     pub fn flood_fill(start: T, adjacent: impl Fn(T) -> Vec<T>) -> HashSet<T> {
         let mut q: VecDeque<T> = VecDeque::new();
         q.push_back(start);
@@ -333,6 +363,39 @@ mod tests {
         bfs_execute(Cell::at(0, 0), Cell::at(4, 0));
     }
 
+    fn bfs_execute_full(start: Cell) -> HashMap<Cell, usize> {
+        #[rustfmt::skip]
+        let v = &vec![
+            ".###",
+            "..##",
+            "#..#",
+            "##..",
+            "###."];
+        let grid = CharGrid::from(&v);
+        let adjacent = |cell| {
+            grid.capital_neighbours(&cell)
+                .iter()
+                .filter(|n| grid.get(&n) != '#')
+                .cloned()
+                .collect()
+        };
+        BFS::execute_full(start, |cell| grid.get(&cell) == '.', adjacent)
+    }
+
+    #[test]
+    pub fn bfs_execute_full_ok() {
+        let dist = bfs_execute_full(Cell::at(0, 0));
+        assert_eq!(dist.len(), 8);
+        assert_eq!(dist[&Cell::at(0, 0)], 0);
+        assert_eq!(dist[&Cell::at(1, 0)], 1);
+        assert_eq!(dist[&Cell::at(1, 1)], 2);
+        assert_eq!(dist[&Cell::at(2, 1)], 3);
+        assert_eq!(dist[&Cell::at(2, 2)], 4);
+        assert_eq!(dist[&Cell::at(3, 2)], 5);
+        assert_eq!(dist[&Cell::at(3, 3)], 6);
+        assert_eq!(dist[&Cell::at(4, 3)], 7);
+    }
+
     #[test]
     pub fn bfs_flood_fill() {
         #[rustfmt::skip]

src/main/rust/aoc/src/grid.rs

@@ -1,6 +1,7 @@
 use crate::geometry::XY;
 use itertools::Itertools;
 use std::cmp::Ordering;
+use std::collections::HashSet;
 use std::fmt::{Display, Error, Formatter};
 
 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
@@ -61,6 +62,25 @@ impl Cell {
         }
         ans
     }
+
+    #[allow(clippy::needless_lifetimes)]
+    pub fn get_all_at_manhattan_distance<'a>(
+        &'a self,
+        distance: usize,
+    ) -> impl Iterator<Item = Cell> + 'a {
+        (0..=distance).flat_map(move |dr| {
+            let dc = distance - dr;
+            let set = HashSet::from([
+                (self.row.checked_add(dr), self.col.checked_add(dc)),
+                (self.row.checked_add(dr), self.col.checked_sub(dc)),
+                (self.row.checked_sub(dr), self.col.checked_add(dc)),
+                (self.row.checked_sub(dr), self.col.checked_sub(dc)),
+            ]);
+            set.into_iter()
+                .filter(|(rr, cc)| rr.is_some() && cc.is_some())
+                .map(|(rr, cc)| Cell::at(rr.unwrap(), cc.unwrap()))
+        })
+    }
 }
 
 impl PartialOrd for Cell {