part 1

2024/Cargo.lock

@@ -189,6 +189,15 @@ dependencies = [
  "smallvec",
 ]
 
+[[package]]
+name = "day09"
+version = "0.1.0"
+dependencies = [
+ "divan",
+ "helper",
+ "nom",
+]
+
 [[package]]
 name = "divan"
 version = "0.1.16"

2024/day09/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "day09"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+nom.workspace = true
+helper.workspace = true
+divan.workspace = true
+
+[[bench]]
+name = "benches"
+harness = false

2024/day09/benches/benches.rs

@@ -0,0 +1,3 @@
+fn main() {
+    day09::bench();
+}

2024/day09/input_small.txt

@@ -0,0 +1 @@
+2333133121414131402

2024/day09/src/lib.rs

@@ -0,0 +1,91 @@
+use std::iter;
+
+use helper::{Day, Variants};
+
+pub fn main() {
+    helper::main::<Day09>(include_str!("../input.txt"));
+}
+
+struct Day09;
+
+helper::define_variants! {
+    day => crate::Day09;
+    part1 {
+        basic => crate::part1;
+    }
+    part2 {
+        basic => crate::part2;
+    }
+}
+
+impl Day for Day09 {
+    fn part1() -> Variants {
+        part1_variants!(construct_variants)
+    }
+
+    fn part2() -> Variants {
+        part2_variants!(construct_variants)
+    }
+}
+
+fn part1(input: &str) -> u64 {
+    let input = &input[0..input.len() - 1];
+
+    let mut blocks = Vec::new();
+    let mut is_file = true;
+    let mut id = 0;
+    for b in input.bytes() {
+        debug_assert!(b.is_ascii_digit());
+        let len = (b - b'0') as usize;
+        if is_file {
+            blocks.extend(iter::repeat_n(Some(id), len));
+            id += 1;
+        } else {
+            blocks.extend(iter::repeat_n(None, len));
+        }
+        is_file = !is_file;
+    }
+
+    let mut next_insert_idx = blocks.iter().position(|b| b.is_none()).unwrap();
+    for i in (0..blocks.len()).rev() {
+        if next_insert_idx >= i {
+            break;
+        }
+
+        match blocks[i] {
+            Some(block) => {
+                blocks[next_insert_idx] = Some(block);
+                blocks[i] = None;
+                next_insert_idx = next_insert_idx
+                    + blocks[next_insert_idx..]
+                        .iter()
+                        .position(|b| b.is_none())
+                        .unwrap();
+            }
+            None => {}
+        }
+    }
+
+    blocks
+        .iter()
+        .enumerate()
+        .filter_map(|(i, b)| b.map(|b| b as u64 * i as u64))
+        .sum()
+}
+
+fn part2(_input: &str) -> u64 {
+    0
+}
+
+helper::tests! {
+    day09 Day09;
+    part1 {
+        small => 1928;
+        default => 6432869891895;
+    }
+    part2 {
+        small => 0;
+        default => 0;
+    }
+}
+helper::benchmarks! {}

2024/day09/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    day09::main();
+}