5th day

Author: majcn

data/examples/05.txt

@@ -0,0 +1,28 @@
+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47

src/bin/05.rs

@@ -0,0 +1,86 @@
+advent_of_code::solution!(5);
+
+use advent_of_code::maneatingape::hash::*;
+use advent_of_code::maneatingape::iter::*;
+use advent_of_code::maneatingape::parse::*;
+use std::cmp::Ordering;
+
+fn parse_data(input: &str) -> (FastMap<u32, Vec<u32>>, Vec<Vec<u32>>) {
+    let (left, right) = input.split_once("\n\n").unwrap();
+
+    let mut rules: FastMap<u32, Vec<u32>> = FastMap::new();
+    left.iter_unsigned().chunk::<2>().for_each(|[key, value]| {
+        rules.entry(key).or_default().push(value);
+    });
+
+    let updates = right
+        .lines()
+        .map(|line| line.iter_unsigned().collect())
+        .collect();
+
+    (rules, updates)
+}
+
+fn validate(rules: &FastMap<u32, Vec<u32>>, update: &[u32]) -> bool {
+    update
+        .iter()
+        .enumerate()
+        .filter_map(|(i, x)| rules.get(x)?.iter().find(|b| update[..i].contains(b)))
+        .next()
+        .is_none()
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let (rules, updates) = parse_data(input);
+
+    let result = updates
+        .iter()
+        .filter(|update| validate(&rules, update))
+        .map(|update| update[update.len() / 2])
+        .sum();
+
+    Some(result)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let (rules, mut updates) = parse_data(input);
+
+    let update_cmp_f = |a: &u32, b: &u32| match rules.get(a) {
+        Some(r) => {
+            if r.contains(b) {
+                Ordering::Less
+            } else {
+                Ordering::Equal
+            }
+        }
+        None => Ordering::Equal,
+    };
+
+    let result = updates
+        .iter_mut()
+        .filter(|update| !validate(&rules, update))
+        .map(|update| {
+            update.sort_unstable_by(update_cmp_f);
+            update[update.len() / 2]
+        })
+        .sum();
+
+    Some(result)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(143));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(123));
+    }
+}