Day 3

Cargo.lock

@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "either"
 version = "1.13.0"
@@ -17,9 +26,45 @@ dependencies = [
  "either",
 ]
 
+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
+[[package]]
+name = "regex"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b15c43186be67a4fd63bee50d0303afffcef381492ebe2c5d87f324e1b8815c"
+
 [[package]]
 name = "testing"
 version = "0.1.0"
 dependencies = [
  "itertools",
+ "regex",
 ]

Cargo.toml

@@ -12,3 +12,4 @@ all = "warn"
 
 [dependencies]
 itertools = "0.13.0"
+regex = "1.11.1"

src/main.rs

@@ -101,9 +101,46 @@ mod day2 {
     }
 }
 
+mod day3 {
+    use std::fs::read_to_string;
+
+    use regex::Regex;
+
+    pub fn task1() {
+        let rx = Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)").unwrap();
+        let mut result: i64 = 0;
+        for c in rx.captures_iter(&read_to_string("input.txt").unwrap()) {
+            let (_, [a, b]) = c.extract();
+            result += a.parse::<i64>().unwrap() * b.parse::<i64>().unwrap();
+        }
+        println!("{result}");
+    }
+
+    pub fn task2() {
+        let rx = Regex::new(r"(mul)\((\d{1,3}),(\d{1,3})\)|do()()()\(\)|do(n't)()()\(\)").unwrap();
+        let mut enabled = true;
+        let mut result: i64 = 0;
+        for c in rx.captures_iter(&read_to_string("input.txt").unwrap()) {
+            let (_, [op, a, b]) = c.extract();
+            match op {
+                "" => enabled = true,
+                "n't" => enabled = false,
+                "mul" if enabled => {
+                    result += a.parse::<i64>().unwrap() * b.parse::<i64>().unwrap();
+                }
+                "mul" => {}
+                _ => unreachable!("{op}"),
+            }
+        }
+        println!("{result}");
+    }
+}
+
 fn main() {
     // day1::task1();
     // day1::task1();
-    day2::task1();
-    day2::task2();
+    // day2::task1();
+    // day2::task2();
+    day3::task1();
+    day3::task2();
 }