[2025] Day 5 draft

Author: connorslade

README.md

@@ -9,6 +9,7 @@ Thank you to [Eric Wastl](http://was.tl) for running this incredible yearly even
 - [Day 02: Gift Shop](aoc_2025/src/day_02.rs)
 - [Day 03: Lobby](aoc_2025/src/day_03.rs)
 - [Day 04: Printing Department](aoc_2025/src/day_04.rs)
+- [Day 05: Cafeteria](aoc_2025/src/day_05.rs)
 <!-- MARKER -->
 
 ## [2024](https://adventofcode.com/2024) [![aoc_2024](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2024.yml/badge.svg)](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2024.yml)

aoc_2025/src/day_05.rs

@@ -0,0 +1,117 @@
+use std::ops::RangeInclusive;
+
+use common::{Answer, solution};
+
+solution!("Cafeteria", 5);
+
+fn part_a(input: &str) -> Answer {
+    let (ranges_raw, nums_raw) = input.split_once("\n\n").unwrap();
+    let mut ranges = Vec::new();
+    for range in ranges_raw.lines() {
+        let (first, last) = range.split_once('-').unwrap();
+        ranges.push(first.parse::<u64>().unwrap()..=last.parse::<u64>().unwrap());
+    }
+
+    let mut out = 0;
+    for num in nums_raw.lines() {
+        let num = num.parse::<u64>().unwrap();
+        if ranges.iter().any(|x| x.contains(&num)) {
+            out += 1;
+            continue;
+        }
+    }
+
+    out.into()
+}
+
+#[derive(Default, Debug)]
+struct Ranges {
+    inner: Vec<RangeInclusive<u64>>,
+}
+
+fn range_intersects(a: &RangeInclusive<u64>, b: &RangeInclusive<u64>) -> bool {
+    a.start() <= b.start() && a.end() >= b.start() || b.start() <= a.start() && b.end() >= a.start()
+}
+
+impl Ranges {
+    fn add(&mut self, new: RangeInclusive<u64>) {
+        for i in 0..self.inner.len() {
+            let range = &self.inner[i];
+            if range_intersects(&range, &new) {
+                let start = *range.start().min(new.start());
+                let end = *range.end().max(new.end());
+                let new = start..=end;
+
+                self.inner.remove(i);
+                self.add(new);
+                return;
+            }
+        }
+
+        self.inner.push(new);
+    }
+
+    fn count(&self) -> u64 {
+        let mut out = 0;
+        for range in &self.inner {
+            out += range.end() - range.start() + 1;
+        }
+
+        out
+    }
+}
+
+fn part_b(input: &str) -> Answer {
+    let (ranges_raw, _s) = input.split_once("\n\n").unwrap();
+    let mut ranges = Ranges::default();
+
+    for range in ranges_raw.lines() {
+        let (first, last) = range.split_once('-').unwrap();
+        let range = first.parse::<u64>().unwrap()..=last.parse::<u64>().unwrap();
+        ranges.add(range);
+    }
+
+    dbg!(&ranges);
+
+    ranges.count().into()
+}
+
+#[cfg(test)]
+mod test {
+    use indoc::indoc;
+
+    const CASE: &str = indoc! {"
+        3-5
+        10-14
+        16-20
+        12-18
+
+        1
+        5
+        8
+        11
+        17
+        32
+    "};
+
+    // const CASE: &str = indoc! {"
+    //     3-5
+    //     2-7
+    //     8-10
+    //     2-9
+
+    // "};
+
+    #[test]
+    fn part_a() {
+        assert_eq!(super::part_a(CASE), 3.into());
+    }
+
+    #[test]
+    fn part_b() {
+        assert_eq!(super::part_b(CASE), 14.into());
+    }
+}
+
+// not: 381374757320727
+// not: 346809913640090

aoc_2025/src/lib.rs

@@ -4,12 +4,14 @@ mod day_01;
 mod day_02;
 mod day_03;
 mod day_04;
+mod day_05;
 // [import_marker]
 
 pub const SOLUTIONS: &[Solution] = &[
     day_01::SOLUTION,
     day_02::SOLUTION,
     day_03::SOLUTION,
     day_04::SOLUTION,
+    day_05::SOLUTION,
     // [list_marker]
 ];