From b3434735e6b3718e01ae1724066f3dd2285d730a Mon Sep 17 00:00:00 2001
From: Julius de Jeu <julius@voidcorp.nl>
Date: Sun, 12 Dec 2021 13:12:38 +0100
Subject: [PATCH] Day 12 but faster

---
 src/day12.rs | 122 ++++++++-------------------------------------------
 1 file changed, 19 insertions(+), 103 deletions(-)

diff --git a/src/day12.rs b/src/day12.rs
index a0b75aa..4526af8 100644
--- a/src/day12.rs
+++ b/src/day12.rs
@@ -26,98 +26,15 @@ impl Day for Day12 {
     }
 
     fn part1(&self) -> anyhow::Result<String> {
-        fn get_all_paths(caves: &HashMap<String, Cave>, complete_paths: &mut Vec<Vec<String>>, current_path: &Vec<String>, current_cave_idx: &str) {
-            if current_cave_idx == "end" {
-                complete_paths.push(current_path.clone());
-                return;
-            }
-
-            let current_cave = caves.get(current_cave_idx).expect("This cave does not exist!").clone();
-
-            for connected_cave in current_cave.connections {
-                let current = caves.get(&connected_cave).unwrap();
-                match current.cave_type {
-                    CaveType::Small => {
-                        if current_path.iter().find(|&cave_pair| cave_pair == &connected_cave) != None {
-                            continue;
-                        }
-                    }
-                    _ => (),
-                }
-
-                let mut new_path = current_path.clone();
-                new_path.push(connected_cave.clone());
-                get_all_paths(&caves, complete_paths, &new_path, &connected_cave);
-            }
-        }
-
-        let mut complete_paths = Vec::new();
-        let current_path = vec!["start".into()];
-
-        get_all_paths(&self.0, &mut complete_paths, &current_path, "start".into());
-
-        Ok(format!("{}", complete_paths.len()))
+        let m = HashMap::new();
+        Ok(format!("{}", self.search("start", &m, true)))
     }
 
     fn part2(&self) -> anyhow::Result<String> {
-        let mut small_caves_thing: HashMap<Vec<String>, Vec<String>> = HashMap::<Vec<String>, Vec<String>>::new();
-        fn get_all_paths(caves: &HashMap<String, Cave>, complete_paths: &mut Vec<Vec<String>>, current_path: &Vec<String>, current_cave_idx: &str, small_caves_thing: &mut HashMap<Vec<String>, Vec<String>>) {
-            if current_cave_idx == "end" {
-                complete_paths.push(current_path.clone());
-                return;
-            }
-
-
-            let current_cave = caves.get(current_cave_idx).expect("This cave does not exist!").clone();
-
-            let small_caves = {
-                let e = small_caves_thing.entry(current_path.clone()).or_insert(small_caves_visited_at_least_twice(caves, current_path));
-                e.clone()
-            };
-
-            for connected_cave in current_cave.connections {
-                if connected_cave == "start" {
-                    continue;
-                }
-                if !small_caves.is_empty() {
-                    let current = caves.get(&connected_cave).unwrap();
-                    match current.cave_type {
-                        CaveType::Small => {
-                            if !(small_caves.len() == 1 && small_caves[0] != connected_cave) {
-                                continue;
-                            }
-                        }
-                        _ => (),
-                    }
-                }
-
-                let mut new_path = current_path.clone();
-                new_path.push(connected_cave.clone());
-                get_all_paths(&caves, complete_paths, &new_path, &connected_cave, small_caves_thing);
-            }
-        }
-
-        let mut complete_paths = Vec::new();
-        let current_path = vec!["start".into()];
-
-        get_all_paths(&self.0, &mut complete_paths, &current_path, "start", &mut small_caves_thing);
-
-        Ok(format!("{}", complete_paths.len()))
+        let m = HashMap::new();
+        Ok(format!("{}", self.search("start", &m, false)))
     }
 }
-
-fn small_caves_visited_at_least_twice(caves: &HashMap<String, Cave>, current_path: &Vec<String>) -> Vec<String> {
-    let mut small_cave_indices = HashMap::new();
-    for cave_name in current_path {
-        let c = caves.get(cave_name).expect("how?");
-        if c.cave_type == CaveType::Small {
-            let e = small_cave_indices.entry(cave_name).or_insert(0);
-            *e += 1;
-        }
-    }
-    return small_cave_indices.iter().filter(|(_, &b)| b > 1).map(|(&a, _)| a.clone()).collect();
-}
-
 #[derive(Ord, PartialOrd, Eq, PartialEq, Copy, Clone)]
 enum CaveType {
     Large,
@@ -153,23 +70,22 @@ impl Cave {
 impl Day12 {
     fn search(&self, cur: &str, had: &HashMap<String, i32>, part1: bool) -> i32 {
         let mut had = had.clone();
-        if had.values().any(|&i| i > 0) || part1 {
+        if had.values().any(|&i| i > 1) || part1 {
             if had.contains_key(cur) {
                 return 0;
             }
         }
-
         if cur == "start" && had.contains_key("start") {
             return 0;
         }
         if cur == "end" {
             return 1;
         }
-        if cur.chars().all(|x| x.is_lowercase()) {
+        let n = self.0.get(cur).unwrap();
+        if n.cave_type == CaveType::Small {
             let e = had.entry(cur.into()).or_insert(0);
             *e += 1;
         }
-        let n = self.0.get(cur).unwrap();
         return n.connections.iter().map(|c| self.search(c, &mut had, part1)).sum::<i32>();
     }
 }
@@ -237,12 +153,12 @@ start-RW";
         Ok(())
     }
 
-    // #[test]
-    // fn part1_real() -> anyhow::Result<()> {
-    //     let d = Day12::init(crate::load_input("12")?)?;
-    //     assert_eq!("4885", d.part1()?);
-    //     Ok(())
-    // }
+    #[test]
+    fn part1_real() -> anyhow::Result<()> {
+        let d = Day12::init(crate::load_input("12")?)?;
+        assert_eq!("4885", d.part1()?);
+        Ok(())
+    }
 
     #[test]
     fn part2_test_1() -> anyhow::Result<()> {
@@ -259,12 +175,12 @@ start-RW";
     }
 
     // These are very slow, so they are commented out.
-    // #[test]
-    // fn part2_test_3() -> anyhow::Result<()> {
-    //     let d = Day12::init(INPUT_3.to_string())?;
-    //     assert_eq!("3509", d.part2()?);
-    //     Ok(())
-    // }
+    #[test]
+    fn part2_test_3() -> anyhow::Result<()> {
+        let d = Day12::init(INPUT_3.to_string())?;
+        assert_eq!("3509", d.part2()?);
+        Ok(())
+    }
 
     #[test]
     fn part2_real() -> anyhow::Result<()> {