2024-09 rust p1

1 files changed, 51 insertions, 0 deletions

diff --git a/2024/09/rust/src/main.rs b/2024/09/rust/src/main.rs
new file mode 100644
index 0000000..1fb892f
--- /dev/null
+++ b/2024/09/rust/src/main.rs
@@ -0,0 +1,51 @@
+#![feature(iter_array_chunks)]
+
+use std::io;
+
+fn main() -> io::Result<()> {
+    let disk_map = io::stdin()
+        .lines()
+        .flatten()
+        .next()
+        .unwrap()
+        .chars()
+        .map(|c| c as u8 - b'0')
+        .collect();
+
+    let silver: usize = silver(&disk_map);
+    let gold: u64 = 0;
+    println!("silver: {silver}");
+    println!("gold: {gold}");
+
+    return Ok(());
+}
+
+fn silver(input: &Vec<u8>) -> usize {
+    let mut blocks = input
+        .iter()
+        .chain([0, 0].iter()) // lol
+        .array_chunks()
+        .enumerate()
+        .map(|(n, [&f, &s])| [[Some(n)].repeat(f as usize), [None].repeat(s as usize)])
+        .flatten()
+        .flatten()
+        .collect::<Vec<_>>();
+
+    let mut l = 0;
+    let mut r = blocks.len() - 1;
+    loop  {
+        while blocks[r].is_none() {
+            r -= 1;
+        }
+        while blocks[l].is_some() {
+            l += 1;
+        }
+        if l >= r {
+            break;
+        }
+        let [left, right] = blocks.get_disjoint_mut([l, r]).unwrap();
+        left.replace(right.take().unwrap());
+    }
+
+    blocks.iter().enumerate().map(|(n, id)| n * id.unwrap_or_default()).sum()
+}