Solve Day 5 Part 1

Author: destinationunknown

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 +1,63 @@
+advent_of_code::solution!(5);
+
+use itertools::Itertools;
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let parts = input.splitn(2, "\n\n").collect::<Vec<&str>>();
+    let rules_section = parts[0];
+    let updates_section = parts[1];
+    let rules: Vec<(i32, i32)> = rules_section
+        .lines()
+        .map(|line| {
+            let l: Vec<&str> = line.splitn(2, '|').collect();
+            (l[0].parse().unwrap(), l[1].parse().unwrap())
+        })
+        .collect();
+
+    let updates: Vec<Vec<i32>> = updates_section
+        .lines()
+        .map(|line| {
+            line.split(',')
+                .filter_map(|x| x.parse::<i32>().ok())
+                .collect::<Vec<i32>>()
+        })
+        .collect();
+
+    updates
+        .iter()
+        .filter(|update| {
+            // combinations will keep pairs in their relative ordering from the original vector
+            update.iter().combinations(2).all(|pair| {
+                let first = pair[0];
+                let second = pair[1];
+                let invalid = rules.iter().any(|(x, y)| first == y && second == x);
+
+                !invalid
+            })
+        })
+        .map(|update| update[update.len() / 2])
+        .sum::<i32>()
+        .try_into()
+        .ok()
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    None
+}
+
+#[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, None);
+    }
+}