From ff241d76cb1c683665cb3701977d05ad702797ad Mon Sep 17 00:00:00 2001
From: Fabian Schmidt <fabschmidt96@gmail.com>
Date: Mon, 16 Dec 2024 20:27:25 +0100
Subject: [PATCH] pre y2024d16p2

---
 y2024/src/days/d16.rs | 103 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 98 insertions(+), 5 deletions(-)

diff --git a/y2024/src/days/d16.rs b/y2024/src/days/d16.rs
index 67671ad..14c8bda 100644
--- a/y2024/src/days/d16.rs
+++ b/y2024/src/days/d16.rs
@@ -1,4 +1,7 @@
-use std::{collections::HashMap, error::Error};
+use std::{
+    collections::{HashMap, HashSet},
+    error::Error,
+};
 
 use itertools::Itertools;
 
@@ -61,7 +64,75 @@ pub fn process_part1(input: &str) -> usize {
 }
 
 pub fn process_part2(input: &str) -> usize {
-    0
+    let mut start = (0, 0);
+    let mut end = (0, 0);
+    let grid = input
+        .lines()
+        .enumerate()
+        .map(|(yidx, row)| {
+            row.chars()
+                .enumerate()
+                .map(|(xidx, chara)| {
+                    let tile = GridTile::try_from(chara).unwrap();
+                    match tile {
+                        GridTile::Wall | GridTile::Path => tile,
+                        GridTile::Start => {
+                            start = (xidx, yidx);
+                            tile
+                        }
+                        GridTile::End => {
+                            end = (xidx, yidx);
+                            tile
+                        }
+                    }
+                })
+                .collect_vec()
+        })
+        .collect_vec();
+    let mut visited = HashSet::new();
+    visited.insert(start);
+    let mut next_paths = vec![Reindeer {
+        coords: start,
+        visited,
+        ..Default::default()
+    }];
+    let mut arrived: Vec<Reindeer> = Vec::new();
+    let mut visited = HashMap::new();
+    while !next_paths.is_empty() {
+        next_paths = next_paths
+            .iter()
+            .map(|reindeer| reindeer.get_all_next_paths(&grid))
+            .collect_vec()
+            .concat();
+        for (idx, reindeer) in next_paths.clone().iter().enumerate().rev() {
+            if let Some(_score) = visited.get_mut(&reindeer.coords) {
+                //if *score < reindeer.score {
+                //    next_paths.remove(idx);
+                //    continue;
+                //} else {
+                //    *score = reindeer.score;
+                //}
+            } else {
+                visited.insert(reindeer.coords, reindeer.score);
+            }
+            if reindeer.state == ReindeerState::Arrived {
+                let arrived_reindeer = next_paths.remove(idx);
+                arrived.push(arrived_reindeer);
+            }
+        }
+    }
+    let min_score = arrived.iter().map(|reindeer| reindeer.score).min().unwrap();
+    let visited = arrived
+        .into_iter()
+        .filter(|reindeer| reindeer.score == min_score)
+        .collect_vec();
+    println!("{visited:?}");
+    let visited = visited
+        .into_iter()
+        .map(|reindeer| reindeer.visited.into_iter().collect_vec())
+        .collect_vec()
+        .concat();
+    visited.iter().unique().count()
 }
 
 #[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq)]
@@ -101,11 +172,12 @@ enum ReindeerState {
     Stuck,
 }
 
-#[derive(Debug, Default, Clone, Copy, Hash, PartialEq, Eq)]
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
 struct Reindeer {
     orientation: Orientation,
     coords: (usize, usize),
     score: usize,
+    visited: HashSet<(usize, usize)>,
     state: ReindeerState,
 }
 
@@ -123,9 +195,12 @@ impl Reindeer {
             Orientation::South => (self.coords.0, self.coords.1 + 1),
             Orientation::North => (self.coords.0, self.coords.1 - 1),
         };
+        let mut visited = self.visited.clone();
+        visited.insert(coords);
         if tile == GridTile::Wall {
             Reindeer {
                 state: ReindeerState::Stuck,
+                visited,
                 ..*self
             }
         } else if tile == GridTile::End {
@@ -133,12 +208,14 @@ impl Reindeer {
                 score: self.score + 1,
                 state: ReindeerState::Arrived,
                 coords,
+                visited,
                 ..*self
             }
         } else {
             Reindeer {
                 score: self.score + 1,
                 coords,
+                visited,
                 ..*self
             }
         }
@@ -157,9 +234,12 @@ impl Reindeer {
             Orientation::South => (self.coords.0 - 1, self.coords.1),
             Orientation::North => (self.coords.0 + 1, self.coords.1),
         };
+        let mut visited = self.visited.clone();
+        visited.insert(coords);
         if tile == GridTile::Wall {
             Reindeer {
                 state: ReindeerState::Stuck,
+                visited,
                 ..*self
             }
         } else if tile == GridTile::End {
@@ -168,12 +248,14 @@ impl Reindeer {
                 state: ReindeerState::Arrived,
                 coords,
                 orientation: self.orientation.turn_clockwise(),
+                visited,
             }
         } else {
             Reindeer {
                 score: self.score + 1001,
                 orientation: self.orientation.turn_clockwise(),
                 coords,
+                visited,
                 ..*self
             }
         }
@@ -192,9 +274,12 @@ impl Reindeer {
             Orientation::South => (self.coords.0 + 1, self.coords.1),
             Orientation::North => (self.coords.0 - 1, self.coords.1),
         };
+        let mut visited = self.visited.clone();
+        visited.insert(coords);
         if tile == GridTile::Wall {
             Reindeer {
                 state: ReindeerState::Stuck,
+                visited,
                 ..*self
             }
         } else if tile == GridTile::End {
@@ -203,12 +288,14 @@ impl Reindeer {
                 state: ReindeerState::Arrived,
                 coords,
                 orientation: self.orientation.turn_counterclockwise(),
+                visited,
             }
         } else {
             Reindeer {
                 score: self.score + 1001,
                 orientation: self.orientation.turn_counterclockwise(),
                 coords,
+                visited,
                 ..*self
             }
         }
@@ -306,8 +393,14 @@ mod tests {
     }
 
     #[test]
-    fn part2() {
+    fn part2_1() {
         let result = process_part2(INPUT_1);
-        assert_eq!(result, 0);
+        assert_eq!(result, 45);
+    }
+
+    #[test]
+    fn part2_2() {
+        let result = process_part2(INPUT_2);
+        assert_eq!(result, 64);
     }
 }