day 4

2 files changed, 81 insertions, 0 deletions

diff --git a/src/2022/4/mod.rs b/src/2022/4/mod.rs
new file mode 100644
index 0000000..60aa353
--- /dev/null
+++ b/src/2022/4/mod.rs
@@ -0,0 +1,77 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+
+use crate::prelude::*;
+
+pub struct Pair {
+    first: (i64, i64),
+    second: (i64, i64),
+}
+
+impl Pair {
+    fn contains(&self) -> bool {
+        range_contains(self.first, self.second)
+            || range_contains(self.second, self.first)
+    }
+
+    fn overlaps(&self) -> bool {
+        range_overlaps(self.first, self.second)
+            || range_overlaps(self.second, self.first)
+    }
+}
+
+fn range_contains(a: (i64, i64), b: (i64, i64)) -> bool {
+    (a.0..=a.1).contains(&b.0) && (a.0..=a.1).contains(&b.1)
+}
+
+fn range_overlaps(a: (i64, i64), b: (i64, i64)) -> bool {
+    (a.0..=a.1).contains(&b.0) || (a.0..=a.1).contains(&b.1)
+}
+
+pub fn parse(fh: File) -> Result<impl Iterator<Item = Pair>> {
+    Ok(parse::lines(fh).map(|line| {
+        let mut parts = line.split(',');
+        let first = parts.next().unwrap();
+        let mut first_parts = first.split('-');
+        let second = parts.next().unwrap();
+        let mut second_parts = second.split('-');
+        Pair {
+            first: (
+                first_parts.next().unwrap().parse().unwrap(),
+                first_parts.next().unwrap().parse().unwrap(),
+            ),
+            second: (
+                second_parts.next().unwrap().parse().unwrap(),
+                second_parts.next().unwrap().parse().unwrap(),
+            ),
+        }
+    }))
+}
+
+pub fn part1(pairs: impl Iterator<Item = Pair>) -> Result<i64> {
+    Ok(pairs
+        .filter(|pair| pair.contains())
+        .count()
+        .try_into()
+        .unwrap())
+}
+
+pub fn part2(pairs: impl Iterator<Item = Pair>) -> Result<i64> {
+    Ok(pairs
+        .filter(|pair| pair.overlaps())
+        .count()
+        .try_into()
+        .unwrap())
+}
+
+#[test]
+fn test() {
+    assert_eq!(
+        part1(parse(parse::data(2022, 4).unwrap()).unwrap()).unwrap(),
+        515
+    );
+    assert_eq!(
+        part2(parse(parse::data(2022, 4).unwrap()).unwrap()).unwrap(),
+        883
+    );
+}
diff --git a/src/2022/mod.rs b/src/2022/mod.rs
index b59d411..1488c13 100644
--- a/src/2022/mod.rs
+++ b/src/2022/mod.rs
@@ -6,6 +6,8 @@ mod day1;
 mod day2;
 #[path = "3/mod.rs"]
 mod day3;
+#[path = "4/mod.rs"]
+mod day4;
 // NEXT MOD
 
 pub fn run(day: u8, puzzle: u8) -> Result<i64> {
@@ -17,6 +19,8 @@ pub fn run(day: u8, puzzle: u8) -> Result<i64> {
         (2, 2) => day2::part2(day2::parse(parse::data(2022, 2)?)?),
         (3, 1) => day3::part1(day3::parse(parse::data(2022, 3)?)?),
         (3, 2) => day3::part2(day3::parse(parse::data(2022, 3)?)?),
+        (4, 1) => day4::part1(day4::parse(parse::data(2022, 4)?)?),
+        (4, 2) => day4::part2(day4::parse(parse::data(2022, 4)?)?),
         // NEXT PART
         _ => Err(anyhow!("unknown puzzle {}-{}", day, puzzle)),
     }