Day 3

Cargo.lock

@@ -17,6 +17,15 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "anstream"
 version = "0.6.18"
@@ -75,6 +84,7 @@ dependencies = [
  "color-eyre",
  "humantime",
  "itertools",
+ "regex",
 ]
 
 [[package]]
@@ -318,11 +328,34 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[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 = "rustc-demangle"

Cargo.toml

@@ -10,3 +10,4 @@ clap = { version = "4.5.21", features = ["derive"] }
 color-eyre = "0.6.3"
 humantime = "2.1.0"
 itertools = "0.13.0"
+regex = "1.11.1"

src/bin/day3.rs

@@ -0,0 +1,74 @@
+use std::time::Instant;
+
+use aoc_2024::{load, print_res};
+use bstr::BString;
+use regex::Regex;
+
+type Parsed<'a> = &'a str;
+
+pub fn parsing(input: &BString) -> color_eyre::Result<Parsed> {
+    core::str::from_utf8(input).map_err(Into::into)
+}
+
+pub fn part1(input: Parsed) {
+    let regex = Regex::new(r#"mul\((\d+),(\d+)\)"#).unwrap();
+    let mut total = 0;
+
+    for capture in regex.captures_iter(input) {
+        let first: u64 = capture.get(1).unwrap().as_str().parse().unwrap();
+        let second: u64 = capture.get(2).unwrap().as_str().parse().unwrap();
+
+        total += first * second;
+    }
+
+    print_res!("Sum of multiplications: {total}");
+}
+
+pub fn part2(input: Parsed) {
+    let regex = Regex::new(r#"don't\(\)|do\(\)|mul\((\d+),(\d+)\)"#).unwrap();
+    let mut total = 0;
+    let mut enabled = true;
+
+    for capture in regex.captures_iter(input) {
+        let instr = capture.get(0).unwrap().as_str();
+
+        match instr {
+            "do()" => enabled = true,
+            "don't()" => enabled = false,
+            // `mul(a,b)`
+            _ => {
+                if !enabled {
+                    continue;
+                }
+
+                let first: u64 = capture.get(1).unwrap().as_str().parse().unwrap();
+                let second: u64 = capture.get(2).unwrap().as_str().parse().unwrap();
+
+                total += first * second;
+            }
+        }
+    }
+
+    print_res!("Sum of multiplications: {total}");
+}
+
+pub fn main() -> color_eyre::Result<()> {
+    let context = load()?;
+
+    let start = Instant::now();
+    let parsed = parsing(&context.input)?;
+    let elapsed = humantime::format_duration(start.elapsed());
+
+    let start = Instant::now();
+    if context.part == 1 {
+        part1(parsed);
+    } else {
+        part2(parsed);
+    }
+    let elapsed_part = humantime::format_duration(start.elapsed());
+
+    println!("  Parsing: {elapsed}");
+    println!("  Solving: {elapsed_part}");
+
+    Ok(())
+}