Add day5

day5/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "day5"
+version = "0.1.0"

day5/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day5"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day5/src/main.rs

@@ -0,0 +1,67 @@
+struct ParsedInput {
+    rules: Vec<(u32, u32)>,
+    pages: Vec<Vec<u32>>,
+}
+
+fn parse(input: &str) -> ParsedInput {
+    let (rules, pages) = input.split_once("\n\n").unwrap();
+    ParsedInput {
+        rules: rules
+            .lines()
+            .map(|line| line.split_once('|').unwrap())
+            .map(|(n1, n2)| (n1.parse().unwrap(), n2.parse().unwrap()))
+            .collect(),
+        pages: pages
+            .lines()
+            .map(|line| line.split(',').map(|n| n.parse().unwrap()).collect())
+            .collect(),
+    }
+}
+
+fn all_rules_apply(rules: &[(u32, u32)], page: &[u32]) -> bool {
+    rules.iter().all(|rule| {
+        let Some(first) = page.iter().enumerate().find(|(_, e)| e == &&rule.0) else {
+            return true;
+        };
+        let Some(second) = page.iter().enumerate().find(|(_, e)| e == &&rule.1) else {
+            return true;
+        };
+        first.0 < second.0
+    })
+}
+
+fn part1(parsed_input: &ParsedInput) -> u32 {
+    parsed_input
+        .pages
+        .iter()
+        .filter(|page| all_rules_apply(&parsed_input.rules, page))
+        .map(|rule| rule[rule.len() / 2])
+        .sum()
+}
+
+fn part2(parsed_input: &ParsedInput) -> u32 {
+    parsed_input
+        .pages
+        .iter()
+        .filter(|page| !all_rules_apply(&parsed_input.rules, page))
+        .fold(vec![], |mut acc, curr| {
+            let mut corrected_page = curr.clone();
+            corrected_page.sort_unstable_by(|a, b| {
+                match all_rules_apply(&parsed_input.rules, &[*a, *b]) {
+                    true => std::cmp::Ordering::Less,
+                    false => std::cmp::Ordering::Greater,
+                }
+            });
+            acc.push(corrected_page);
+            acc
+        })
+        .iter()
+        .map(|rule| rule[rule.len() / 2])
+        .sum()
+}
+
+fn main() {
+    let input = parse(include_str!("../input.txt"));
+    println!("{}", part1(&input));
+    println!("{}", part2(&input));
+}