Day3

day3/rust/src/main.rs

@@ -0,0 +1,45 @@
+use std::io::Read;
+
+use regex::Regex;
+
+fn main() {
+    let mut stdin = std::io::stdin();
+
+    let mut input = String::new();
+    stdin.read_to_string(&mut input).unwrap();
+
+    let regex = Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)|do\(\)|don't\(\)").unwrap();
+
+    let mut enabled = true;
+
+    let mut sum = 0;
+    let mut sum2 = 0;
+    for capture in regex.captures_iter(&input) {
+        let matched = capture.get(0).unwrap().as_str();
+        match matched {
+            "do()" => {
+                enabled = true;
+                continue;
+            }
+            "don't()" => {
+                enabled = false;
+                continue;
+            }
+            _ => (),
+        }
+
+        let (a, b): (isize, isize) = (
+            capture.get(1).unwrap().as_str().parse().unwrap(),
+            capture.get(2).unwrap().as_str().parse().unwrap(),
+        );
+
+        sum += a * b;
+
+        if enabled {
+            sum2 += a * b;
+        }
+    }
+
+    println!("{}", sum);
+    println!("{}", sum2);
+}