feat: lots of optimization in parse, cargo bench

2025/Cargo.lock

···
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "atoi_simd",
+ "memchr",
 ]
+
+[[package]]
+name = "atoi_simd"
+version = "0.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ad17c7c205c2c28b527b9845eeb91cf1b4d008b438f98ce0e628227a822758e"
+dependencies = [
+ "debug_unsafe",
+]
+
+[[package]]
+name = "debug_unsafe"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85d3cef41d236720ed453e102153a53e4cc3d2fde848c0078a50cf249e8e3e5b"
+
+[[package]]
+name = "memchr"
+version = "2.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f52b00d39961fc5b2736ea853c9cc86238e165017a493d1d5c8eac6bdc4cc273"

2025/Cargo.toml

···
 
 [dependencies]
 anyhow = "1.0.100"
+atoi_simd = "0.17.0"
+memchr = "2.7.6"

2025/src/days/one/secret_entrance.rs

···
+use atoi_simd::parse as parse_i32;
+
 pub fn main() -> anyhow::Result<()> {
     crate::run("Secret Entrance", "inputs/day1.txt", parse, part_a, part_b)
 }
 
-fn parse(input: &str) -> Vec<i32> {
-    input
-        .lines()
-        .filter(|line| !line.is_empty())
-        .filter_map(|line| line.replace("L", "-").replace("R", "").parse().ok())
-        .collect()
+fn parse(input: &[u8]) -> Vec<i32> {
+    let mut out = Vec::with_capacity(4503);
+    let mut start = 0;
+
+    while start < input.len() {
+        let end = match memchr::memchr(b'\n', &input[start..]) {
+            Some(index) => start + index,
+            None => input.len(),
+        };
+        let line = &input[start..end];
+
+        if !line.is_empty() {
+            let mut buf = [0u8; 4];
+            let mut len = 0usize;
+            let mut seen_digit = false;
+
+            for &b in line {
+                match b {
+                    b'L' => {
+                        if len == 0 {
+                            buf[len] = b'-';
+                            len += 1;
+                        }
+                    }
+                    b'0'..=b'9' => {
+                        seen_digit = true;
+                        buf[len] = b;
+                        len += 1;
+                    }
+                    _ => {
+                        len = 0;
+                        break;
+                    }
+                }
+            }
+            if seen_digit && len > 0 {
+                if let Ok(num) = parse_i32(&buf[..len]) {
+                    out.push(num);
+                }
+            }
+        }
+
+        start = end + 1;
+    }
+
+    out
 }
 
 fn part_a(input: Vec<i32>) -> usize {

2025/src/lib.rs

···
 ) -> Result<()>
 where
     T: Clone,
-    P: Fn(&str) -> T,
+    P: Fn(&[u8]) -> T,
     A: Fn(T) -> RA,
     B: Fn(T) -> RB,
     RA: Display,
     RB: Display,
 {
+    let file = &fs::read_to_string(input_path)?;
+    let bytes = file.as_bytes();
     let label_parse = format!("{name} Parse");
     let parse_start = Instant::now();
-    let input = parse(&fs::read_to_string(input_path)?);
+    let input = parse(bytes);
     let parse_elapsed = parse_start.elapsed();
     println!("{label_parse}");
     println!("{}", "-".repeat(label_parse.len()));

2025/src/main.rs

···
+#![feature(test)]
+extern crate test;
+
 fn main() -> anyhow::Result<()> {
     aoc2025::days::one::secret_entrance::main()?;
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use aoc2025::days;
+    use test::Bencher;
+
+    #[bench]
+    fn day1(b: &mut Bencher) {
+        b.iter(|| days::one::secret_entrance::main())
+    }
+}