finish day 14

src/day14.rs

@@ -28,25 +28,53 @@ fn part_one(input: String, transforms: Transforms) -> i32 {
             );
         }
     }
-    counts.iter().fold(0, |max, (_, count)| {
-        let count = *count;
-        if count > max {
-            count
-        } else {
-            max
-        }
-    }) - counts.iter().fold(i32::max_value(), |min, (_, count)| {
-        let count = *count;
-        if count < min {
-            count
-        } else {
-            min
-        }
-    })
+    counts.iter().max_by_key(|c| c.1).unwrap().1 - counts.iter().min_by_key(|c| c.1).unwrap().1
 }
 
 fn part_two(input: String, transforms: Transforms) -> u128 {
-    todo!()
+    type Bag = HashMap<(char, char), u128>;
+    let mut last_pair = ('a', 'b'); //hacky
+    let mut bag = {
+        let mut bag = Bag::new();
+        let mut iter1 = input.chars().filter(|c| *c != '\n');
+        let mut iter2 = iter1.clone();
+        iter2.next();
+        while let (Some(c1), Some(c2)) = (iter1.next(), iter2.next()) {
+            last_pair = (c1, c2);
+            bag.entry((c1, c2)).and_modify(|e| *e += 1).or_insert(1);
+        }
+        bag
+    };
+    for _ in 0..40 {
+        let mut new_bag = Bag::new();
+        for ((c1, c2), val) in bag {
+            let transformation = transforms[&(c1, c2)];
+            if last_pair == (c1, c2) {
+                last_pair = (transformation, c2);
+            }
+            new_bag
+                .entry((c1, transformation))
+                .and_modify(|e| *e += val)
+                .or_insert(val);
+            new_bag
+                .entry((transformation, c2))
+                .and_modify(|e| *e += val)
+                .or_insert(val);
+        }
+        bag = new_bag;
+    }
+    let counts = {
+        type Counts = HashMap<char, u128>;
+        let mut counts = Counts::new();
+        for ((c1, _), val) in bag {
+            counts.entry(c1).and_modify(|e| *e += val).or_insert(val);
+        }
+        counts.entry(last_pair.1).and_modify(|e| *e += 1);
+        counts
+    };
+
+    counts.iter().max_by_key(|(_, val)| **val).unwrap().1
+        - counts.iter().min_by_key(|(_, val)| **val).unwrap().1
 }
 
 #[cfg(test)]
@@ -56,7 +84,7 @@ mod tests {
     fn parse_input(input: &str) -> (String, Transforms) {
         let (input, transform_list) = input.split_once("\n\n").expect("two sections");
         let mut transforms = Transforms::new();
-        for line in transform_list.split("\n") {
+        for line in transform_list.split('\n') {
             let (input, output) = line.split_once(" -> ").expect("transform");
             let mut chars = input.chars();
             transforms.insert(
@@ -78,4 +106,16 @@ mod tests {
         let (input, transforms) = parse_input(include_str!("../inputs/14.txt"));
         assert_eq!(part_one(input, transforms), 2112);
     }
+
+    #[test]
+    fn part_two_sample() {
+        let (input, transforms) = parse_input(include_str!("../inputs/14_test.txt"));
+        assert_eq!(part_two(input, transforms), 2188189693529);
+    }
+
+    #[test]
+    fn part_two_test() {
+        let (input, transforms) = parse_input(include_str!("../inputs/14.txt"));
+        assert_eq!(part_two(input, transforms), 3243771149914);
+    }
 }

src/lib.rs

@@ -4,10 +4,10 @@
  * File: lib.rs
  * Author: Adam Jeniski; @Ajetski
  */
-
 pub(crate) mod day1;
-pub(crate) mod day9;
 pub(crate) mod day10;
+pub(crate) mod day9;
 //pub(crate) mod day11; //todo, finish day11
 pub(crate) mod day13;
 pub(crate) mod day14;
+pub(crate) mod day15;