4 files changed, 175 insertions, 0 deletions
diff --git a/aoc/2024/09/python.py b/aoc/2024/09/python.py
new file mode 100755
index 0000000..1cf450e
--- /dev/null
+++ b/aoc/2024/09/python.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+
+from fileinput import input
+
+disk = list(input())[0].strip()
+
+id_ = -1
+blocks = []
+tail = 0
+file = True
+for c in disk:
+    blocks.append([tail, tail + int(c), (id_ := id_ + 1) if file else -1])
+    tail += int(c)
+    file = not file
+
+
+def expand(bs):
+    return [x for a, b, x in sorted(bs) for _ in range(b - a)]
+
+
+def debug(bs):
+    print("".join(str(b) if b != -1 else "." for b in expand(bs)))
+
+
+# Silver
+expanded = expand(blocks)
+tail = len(expanded) - 1
+fill = expanded.index(-1)
+while fill < tail:
+    expanded[fill] = expanded[tail]
+    expanded[tail] = -1
+    while expanded[tail] == -1:
+        tail -= 1
+    while expanded[fill] != -1:
+        fill += 1
+silver = sum(idx * n for idx, n in enumerate(expanded) if n != -1)
+
+
+# Gold
+for move in blocks[::-1]:
+    print(move)
+    ma, mb, mx = move
+    if mx == -1:
+        continue
+    mlen = mb - ma
+    for tidx, to in enumerate(blocks):
+        ta, tb, tx = to
+        if ta >= ma:
+            break
+        if tx != -1:
+            continue
+        if (tlen := tb - ta) < mlen:
+            continue
+        move[2] = -1
+        to[2] = mx
+        to[1] = ta + mlen
+        blocks.insert(tidx + 1, [ta + mlen, tb, -1])
+        break
+gold = sum(idx * n for idx, n in enumerate(expand(blocks)) if n != -1)
+
+print("silver:", silver)
+print("gold:", gold)
diff --git a/aoc/2024/09/rust/Cargo.lock b/aoc/2024/09/rust/Cargo.lock
new file mode 100644
index 0000000..ac79b17
--- /dev/null
+++ b/aoc/2024/09/rust/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "puzzle"
+version = "0.1.0"
diff --git a/aoc/2024/09/rust/Cargo.toml b/aoc/2024/09/rust/Cargo.toml
new file mode 100644
index 0000000..88e7b42
--- /dev/null
+++ b/aoc/2024/09/rust/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "puzzle"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
diff --git a/aoc/2024/09/rust/src/main.rs b/aoc/2024/09/rust/src/main.rs
new file mode 100644
index 0000000..fa7c021
--- /dev/null
+++ b/aoc/2024/09/rust/src/main.rs
@@ -0,0 +1,100 @@
+#![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: usize = gold(&disk_map);
+    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()
+}
+
+fn gold(input: &Vec<u8>) -> usize {
+    let mut blocks = input
+        .iter()
+        .chain([0, 0].iter()) // lol
+        .array_chunks()
+        .enumerate()
+        .map(|(n, [&f, &s])| [(Some(n), f as usize), (None, s as usize)])
+        .flatten()
+        .collect::<Vec<_>>();
+
+    let mut r = blocks.len();
+    while r > 0 {
+        r -= 1;
+        let (Some(_), f) = blocks[r] else {
+            continue;
+        };
+
+        // find some empty space and maybe split
+        let Some(l) = blocks.iter().position(|b| b.0.is_none() && b.1 >= f) else {
+            continue;
+        };
+        if l > r {
+            continue;
+        };
+
+        let (_, s) = &mut blocks[l];
+
+        let diff = *s - f;
+        if diff > 0 {
+            *s = f;
+            blocks.insert(l + 1, (None, diff));
+            r += 1;
+        }
+        blocks.swap(l, r);
+    }
+
+    blocks
+        .iter()
+        .map(|&(id, n)| [id].repeat(n))
+        .flatten()
+        .enumerate()
+        .map(|(n, id)| n * id.unwrap_or_default())
+        .sum()
+}