day 14 part 1

Author: mflinn-broad

src/days/day14.rs

@@ -0,0 +1,70 @@
+use crate::util;
+use std::collections::HashMap;
+
+type Input = (
+    HashMap<String, String>,
+    HashMap<String, usize>,
+    HashMap<String, usize>,
+);
+
+pub fn run() {
+    let raw_input = util::read_input("inputs/day14.txt").unwrap();
+    let input = process(&raw_input);
+    println!("Part 1: {}", part_1(input));
+}
+
+fn part_1(input: Input) -> usize {
+    let (mappings, mut singles, pairs) = input;
+    (0..10).fold(pairs, |old_pairs, _| {
+        let mut new_pairs: HashMap<String, usize> = HashMap::new();
+
+        old_pairs.iter().for_each(|(pair, pair_count)| {
+            let single = mappings.get(pair).unwrap();
+            let single_count = singles.get_mut(single).unwrap();
+            *single_count += pair_count;
+
+            let new_pair_a = format!("{}{}", pair.chars().nth(0).unwrap(), single);
+            let new_pair_b = format!("{}{}", single, pair.chars().nth(1).unwrap());
+
+            let new_pair_a_count = new_pairs.entry(new_pair_a).or_insert(0);
+            *new_pair_a_count += pair_count;
+
+            let new_pair_b_count = new_pairs.entry(new_pair_b).or_insert(0);
+            *new_pair_b_count += pair_count;
+        });
+
+        new_pairs
+    });
+
+    let min = singles.values().min().unwrap();
+    let max = singles.values().max().unwrap();
+
+    max - min
+}
+
+fn process(input: &str) -> Input {
+    let mut singles: HashMap<String, usize> = HashMap::new();
+    let mut pairs: HashMap<String, usize> = HashMap::new();
+    let mut mappings: HashMap<String, String> = HashMap::new();
+
+    let (initial, instructions) = input.split_once("\n\n").unwrap();
+
+    initial.trim().chars().for_each(|poly| {
+        let poly_count = singles.entry(poly.to_string()).or_insert(0);
+        *poly_count += 1;
+    });
+
+    let initial: Vec<char> = initial.trim().chars().collect();
+    initial.windows(2).for_each(|pair| {
+        let pair: String = pair.iter().collect();
+        let pair_count = pairs.entry(pair).or_insert(0);
+        *pair_count += 1;
+    });
+
+    instructions.lines().for_each(|line| {
+        let (pair, poly) = line.trim().split_once(" -> ").unwrap();
+        mappings.insert(pair.to_string(), poly.to_string());
+    });
+
+    (mappings, singles, pairs)
+}

src/days/mod.rs

@@ -3,6 +3,7 @@ pub mod day10;
 pub mod day11;
 pub mod day12;
 pub mod day13;
+pub mod day14;
 pub mod day2;
 pub mod day3;
 pub mod day4;

src/main.rs

@@ -71,6 +71,11 @@ fn main() {
     day13::run();
     day_durations.insert(13, day_13_start.elapsed());
 
+    let day_14_start = Instant::now();
+    println!("Day 14 --------");
+    day14::run();
+    day_durations.insert(14, day_14_start.elapsed());
+
     let total_duration = start.elapsed();
 
     println!("Total time to run all solutions: {:?}", total_duration);