Day 3

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(())
+}