1 files changed, 35 insertions, 0 deletions
diff --git a/2022/src/day04.rs b/2022/src/day04.rs
new file mode 100644
index 0000000..052dde1
--- /dev/null
+++ b/2022/src/day04.rs
@@ -0,0 +1,35 @@
+mod utils;
+
+use std::ops::RangeInclusive;
+
+use utils::{iter_pair, read_input};
+
+fn main() {
+    let input = read_input();
+
+    let pairs = input.lines().map(|x| {
+        iter_pair(x.split(',').map(|x| -> RangeInclusive<usize> {
+            let (start, end) = iter_pair(x.split('-'));
+            start.parse().unwrap()..=end.parse().unwrap()
+        }))
+    });
+
+    let (fully_contains, partially_contains) = pairs
+        .map(|(a, b)| (fully_overlap(&a, &b), partially_overlap(&a, &b)))
+        .fold((0, 0), |(acc_full, acc_part), (full, part)| {
+            (acc_full + full as usize, acc_part + part as usize)
+        });
+
+    println!("Part 1: {}", fully_contains);
+    println!("Part 2: {}", partially_contains);
+}
+
+#[inline(always)]
+fn fully_overlap<T: PartialOrd>(a: &RangeInclusive<T>, b: &RangeInclusive<T>) -> bool {
+    (a.contains(b.start()) && a.contains(b.end())) || (b.contains(a.start()) && b.contains(a.end()))
+}
+
+#[inline(always)]
+fn partially_overlap<T: PartialOrd>(a: &RangeInclusive<T>, b: &RangeInclusive<T>) -> bool {
+    a.contains(b.start()) || a.contains(b.end()) || b.contains(a.start()) || b.contains(a.end())
+}