Day 17 part 2

1 files changed, 25 insertions, 15 deletions

diff --git a/2023/src/bin/day_17.rs b/2023/src/bin/day_17.rs
index 99d828b..8d839e5 100644
--- a/2023/src/bin/day_17.rs
+++ b/2023/src/bin/day_17.rs
@@ -10,7 +10,8 @@ use std::{collections::HashSet, fs};
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let input = fs::read_to_string("inputs/day_17.txt")?;
     let parsed = HeatlossMap::parser(&input).unwrap().1;
-    dbg!(&parsed.find_shortest_heatloss_path());
+    dbg!(&parsed.find_shortest_heatloss_path(false));
+    dbg!(&parsed.find_shortest_heatloss_path(true));
 
     Ok(())
 }
@@ -44,7 +45,7 @@ impl HeatlossMap {
         )(input)
     }
 
-    fn find_shortest_heatloss_path(&self) -> u32 {
+    fn find_shortest_heatloss_path(&self, is_ultra_crucible: bool) -> u32 {
         let start = Position {
             pos: Point2::new(0, 0),
             facing: Vector2::x_axis(),
@@ -64,25 +65,28 @@ impl HeatlossMap {
             let (front_distance, front_position) = frontier.pop().unwrap();
 
             let mut next_points: Vec<Position> = Vec::new();
-            {
-                let facing = rotate_left(&front_position.facing);
-                let pos = front_position.pos + *facing;
+
+            if !is_ultra_crucible || front_position.duration_with_facing >= 4 {
+                let facing_l = rotate_left(&front_position.facing);
+                let pos_l = front_position.pos + *facing_l;
                 next_points.push(Position {
-                    pos,
-                    facing,
+                    pos: pos_l,
+                    facing: facing_l,
                     duration_with_facing: 1,
                 });
-            }
-            {
-                let facing = rotate_right(&front_position.facing);
-                let pos = front_position.pos + *facing;
+
+                let facing_r = rotate_right(&front_position.facing);
+                let pos_r = front_position.pos + *facing_r;
                 next_points.push(Position {
-                    pos,
-                    facing,
+                    pos: pos_r,
+                    facing: facing_r,
                     duration_with_facing: 1,
                 });
             }
-            if front_position.duration_with_facing < 3 {
+
+            if (is_ultra_crucible && front_position.duration_with_facing < 10)
+                || (!is_ultra_crucible && front_position.duration_with_facing < 3)
+            {
                 let pos = front_position.pos + *front_position.facing;
                 next_points.push(Position {
                     pos,
@@ -99,7 +103,13 @@ impl HeatlossMap {
                         let distance = front_distance + step_distance;
 
                         if next_point.pos == end_pos {
-                            distance_to_end = Some(distance);
+                            if is_ultra_crucible {
+                                if next_point.duration_with_facing >= 4 {
+                                    distance_to_end = Some(distance);
+                                }
+                            } else {
+                                distance_to_end = Some(distance);
+                            }
                         }
                         frontier.push((distance, next_point));
                     }