day(18): refactor a bit

Not enough for part 2 though…

Signed-off-by: Matej Focko <me@mfocko.xyz>

src/bin/day18.rs

@@ -1,8 +1,9 @@
 use std::{collections::VecDeque, str::FromStr};
 
-use aoc_2023::*;
 use itertools::iproduct;
 
+use aoc_2023::*;
+
 type Output1 = usize;
 type Output2 = Output1;
 
@@ -70,18 +71,8 @@ fn flood_fill(m: &mut [Vec<char>], start: Vector2D<isize>, original: char, fill:
     filled_in
 }
 
-struct Day18 {
-    plan: Vec<Step>,
-}
-impl Solution<Output1, Output2> for Day18 {
-    fn new<P: AsRef<Path>>(pathname: P) -> Self {
-        Self {
-            plan: file_to_structs(pathname),
-        }
-    }
-
-    fn part_1(&mut self) -> Output1 {
-        let (min_x, max_x, min_y, max_y) = self.plan.iter().fold((0, 0, 0, 0), |dimensions, s| {
+fn solve(plan: &[Step]) -> usize {
+    let (min_x, max_x, min_y, max_y) = plan.iter().fold((0, 0, 0, 0), |dimensions, s| {
         let (mut lx, mut ux, mut ly, mut uy) = dimensions;
 
         match s._direction {
@@ -95,27 +86,18 @@ impl Solution<Output1, Output2> for Day18 {
         (lx, ux, ly, uy)
     });
     let (width, height) = (min_x + max_x + 1, min_y + max_y + 1);
-
     debug!("Dimensions: {}×{}", width, height);
 
     let mut map = vec![vec!['.'; width as usize]; height as usize];
     let mut position = Vector2D::new(min_x, min_y);
-        // debug!("Initial position: {:?}", position);
 
-        // let (mut min_x, mut max_x, mut min_y, mut max_y) = (isize::MAX, isize::MIN, isize::MAX, isize::MIN);
-        for s in &self.plan {
+    for s in plan.iter() {
         let direction = s.direction();
         for _ in 0..s.count {
-                // min_x = std::cmp::min(min_x, position.x());
-                // max_x = std::cmp::max(max_x, position.x());
-                // min_y = std::cmp::min(min_y, position.y());
-                // max_y = std::cmp::max(max_y, position.y());
-
             map[position] = '#';
             position = position + direction;
         }
     }
-        // debug!("x ∈ ⟨{} ; {}⟩\ty ∈ ⟨{} ; {}⟩", min_x, max_x, min_y, max_y);
 
     flood_fill(&mut map, Vector2D::new(0, 0), '.', '+');
 
@@ -133,10 +115,47 @@ impl Solution<Output1, Output2> for Day18 {
     map.iter()
         .map(|r| r.iter().filter(|&&c| c == '#').count())
         .sum()
+}
+
+struct Day18 {
+    plan: Vec<Step>,
+}
+impl Solution<Output1, Output2> for Day18 {
+    fn new<P: AsRef<Path>>(pathname: P) -> Self {
+        Self {
+            plan: file_to_structs(pathname),
+        }
+    }
+
+    fn part_1(&mut self) -> Output1 {
+        solve(&self.plan)
     }
 
     fn part_2(&mut self) -> Output2 {
-        todo!()
+        solve(
+            &self
+                .plan
+                .iter()
+                .map(|s| {
+                    let new_step = s.color.trim_matches('#');
+                    let number = isize::from_str_radix(new_step, 16).unwrap();
+
+                    let _direction = match number % 16 {
+                        0 => (1, 0),
+                        1 => (0, 1),
+                        2 => (-1, 0),
+                        3 => (0, -1),
+                        _ => unreachable!(),
+                    };
+
+                    Step {
+                        _direction,
+                        count: number >> 8,
+                        color: String::new(),
+                    }
+                })
+                .collect_vec(),
+        )
     }
 }