Day 4, puzzle 2

src/bin/d4p2.rs

@@ -0,0 +1,9 @@
+use aoc22::{day4, util};
+
+pub fn main() {
+    let assignments = day4::parse_assignments(&util::parse_input());
+
+    let overlapping = assignments.iter().filter(|a| a.0.overlaps(&a.1)).count();
+
+    println!("{} assignments overlap", overlapping);
+}

src/day4.rs

@@ -10,6 +10,10 @@ impl Assignment {
     pub fn contains(&self, other: &Self) -> bool {
         self.lower_bound <= other.lower_bound && self.upper_bound >= other.upper_bound
     }
+
+    pub fn overlaps(&self, other: &Self) -> bool {
+        self.lower_bound <= other.upper_bound && self.upper_bound >= other.lower_bound
+    }
 }
 
 pub fn parse_assignments(input: &String) -> Vec<(Assignment, Assignment)> {