3 files changed, 45 insertions, 1 deletions
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4648da8
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/AoC2022/*/solver
diff --git a/AoC2022/04/makefile b/AoC2022/04/makefile
index f4940ca..a7661bd 100644
--- a/AoC2022/04/makefile
+++ b/AoC2022/04/makefile
@@ -11,4 +11,4 @@
 run:
 	sbcl --load ~/.sbclrc --script solver.lisp
 	emacs -batch -l ert -l solver.el -f ert-run-tests-batch-and-exit
-	# rustc solver.rs && ./solver
+	rustc solver.rs && ./solver
diff --git a/AoC2022/04/solver.rs b/AoC2022/04/solver.rs
new file mode 100644
index 0000000..8b979fa
--- /dev/null
+++ b/AoC2022/04/solver.rs
@@ -0,0 +1,43 @@
+use std::fs;
+use std::io::{self, BufRead};
+
+// fn subinterval(a0: i32, a1: i32, b0: i32, b1: i32) -> bool {
+//     a0 <= b0 && b1 <= a1
+// }
+
+fn subcontained(a0: i32, a1: i32, b0: i32, b1: i32) -> bool {
+    // subinterval(a0, a1, b0, b1) || subinterval(b0, b1, a0, a1)
+    ((a0 - b0) * (a1 - b1)) <= 0
+}
+
+fn overlap(a0: i32, a1: i32, b0: i32, b1: i32) -> bool {
+    a0 <= b1 && b0 <= a1
+}
+
+fn main() {
+    let file = fs::File::open("input").unwrap();
+    let lines = io::BufReader::new(file).lines();
+    let mut subcont = 0;
+    let mut overlaps = 0;
+    for line in lines {
+        let li = line.expect("line");
+        if let [a0, a1, b0, b1] = li
+            .split(&[',', '-'])
+            .map(|x| x.parse::<i32>().unwrap())
+            .collect::<Vec<i32>>()[..4]
+        {
+            if subcontained(a0, a1, b0, b1) {
+                subcont += 1
+            }
+            if overlap(a0, a1, b0, b1) {
+                overlaps += 1
+            }
+        } else {
+            panic!("Bad line input")
+        };
+    }
+
+    assert_eq!(515, subcont);
+    assert_eq!(883, overlaps);
+    println!("All test passed.")
+}