day1

2023/day1/src/main.rs

@@ -0,0 +1,49 @@
+use std::mem::MaybeUninit;
+
+mod branchless;
+mod naive;
+mod zero_alloc;
+
+fn main() {
+    let kind = std::env::args().nth(1).unwrap_or("naive".into());
+
+    let mut input = std::hint::black_box(include_str!("../input.txt")).to_owned();
+
+    input.reserve(5);
+    unsafe {
+        input
+            .as_mut_vec()
+            .spare_capacity_mut()
+            .fill(MaybeUninit::new(0))
+    };
+
+    match kind.as_str() {
+        "part1" => part1(&input),
+        "naive" => naive::part2(&input),
+        "zero_alloc" => zero_alloc::part2(&input),
+        "branchless" => unsafe { branchless::part2(&input) },
+        _ => {
+            eprintln!("error: invalid mode, must be part1,naive,zero_alloc,branchless");
+            std::process::exit(1);
+        }
+    }
+}
+
+fn part1(input: &str) {
+    let sum = input
+        .lines()
+        .map(|line| {
+            let mut chars = line.chars().filter(|c| c.is_ascii_digit());
+            let first = chars.next().unwrap();
+            let last = chars.next_back().unwrap_or(first);
+
+            [first, last]
+                .into_iter()
+                .collect::<String>()
+                .parse::<u64>()
+                .unwrap()
+        })
+        .sum::<u64>();
+
+    println!("part1: {sum}");
+}