Day 10

Author: prevostc

README.md

@@ -20,8 +20,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 7](./src/bin/07.rs) | `316.2µs` | `319.6µs` |
 | [Day 8](./src/bin/08.rs) | `7.4µs` | `15.5µs` |
 | [Day 9](./src/bin/09.rs) | `149.0µs` | `6.5ms` |
+| [Day 10](./src/bin/10.rs) | `43.4µs` | `36.3µs` |
 
-**Total: 12.65ms**
+**Total: 12.73ms**
 <!--- benchmarking table --->
 
 ---

data/examples/10.txt

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

src/bin/10.rs

@@ -0,0 +1,133 @@
+use heapless::FnvIndexSet;
+use mygrid::{direction::ORTHOGONAL, grid::Grid, point::Point};
+use std::collections::VecDeque;
+
+type Found = FnvIndexSet<Point, 128>;
+
+advent_of_code::solution!(10);
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let grid: Grid<u8> = Grid::new_from_str(input, |c| c.to_digit(10).unwrap() as u8);
+
+    let trailheads = grid
+        // TODO: par_iter_item_and_position()
+        .iter_item_and_position()
+        .filter(|(_, &value)| value == 0)
+        .map(|(pos, _)| pos);
+
+    let trailhead_scores = trailheads
+        .map(|starting_point| {
+            let mut visited = Grid::new(grid.width, grid.height, false);
+            let mut found = Found::new();
+
+            let mut q = VecDeque::with_capacity(128);
+            q.push_back(starting_point);
+            visited[starting_point] = true;
+
+            while let Some(current) = q.pop_front() {
+                visited[current] = true;
+                if grid[current] == 9 {
+                    visited[current] = true;
+                    found.insert(current).unwrap();
+                    continue;
+                }
+                for n in ORTHOGONAL
+                    .iter()
+                    .map(|&dir| current + dir)
+                    .filter(|&p| grid.is_in_bounds(p))
+                    .filter(|&p| grid[p] == grid[current] + 1)
+                    .filter(|&p| !visited[p])
+                {
+                    q.push_front(n);
+                }
+            }
+
+            found.len() as u32
+        })
+        .sum();
+
+    Some(trailhead_scores)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let grid: Grid<u8> = Grid::new_from_str(input, |c| c.to_digit(10).unwrap() as u8);
+
+    let trailheads = grid
+        // TODO: par_iter_item_and_position()
+        .iter_item_and_position()
+        .filter(|(_, &value)| value == 0)
+        .map(|(pos, _)| pos);
+
+    let trailhead_scores = trailheads
+        .map(|starting_point| {
+            let mut found = 0;
+
+            let mut q = VecDeque::with_capacity(128);
+            q.push_back(starting_point);
+
+            while let Some(current) = q.pop_front() {
+                if grid[current] == 9 {
+                    found += 1;
+                    continue;
+                }
+                for n in ORTHOGONAL
+                    .iter()
+                    .map(|&dir| current + dir)
+                    .filter(|&p| grid.is_in_bounds(p))
+                    .filter(|&p| grid[p] == grid[current] + 1)
+                {
+                    q.push_front(n);
+                }
+            }
+
+            found
+        })
+        .sum();
+
+    Some(trailhead_scores)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one_1() {
+        let input = "0123\n1234\n8765\n9876\n";
+        let result = part_one(&input);
+        assert_eq!(result, Some(1));
+    }
+
+    #[test]
+    fn test_part_one_2() {
+        let input = "8880888\n8881888\n8882888\n6543456\n7888887\n8888888\n9888889\n";
+        let result = part_one(&input);
+        assert_eq!(result, Some(2));
+    }
+
+    #[test]
+    fn test_part_one_3() {
+        let input = "8890889\n8881898\n8882887\n6543456\n7658987\n8768888\n9878888\n";
+        let result = part_one(&input);
+        assert_eq!(result, Some(4));
+    }
+
+    #[test]
+    fn test_part_one_4() {
+        let input = "1088988\n2888888\n3888788\n4567654\n8888883\n8889882\n8888801\n";
+        let result = part_one(&input);
+        assert_eq!(result, Some(3));
+    }
+
+    #[test]
+    fn test_part_one_5() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(36));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(81));
+    }
+}