Day 11

.gitignore

@@ -1,4 +1,5 @@
 **/input.txt
 **/example.txt
 .direnv
-node_modules
+node_modules
+target

Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aoc2024"
+version = "0.1.0"

Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "aoc2024"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name = "d11p2"
+path = "day11/part2.rs"

day11/part1.kts

@@ -0,0 +1,27 @@
+#!/usr/bin/env kotlin
+
+import java.io.File
+import java.util.LinkedList
+import kotlin.math.log10
+
+val stones = LinkedList(File("input.txt").readLines()[0].split(" ").map { it.toLong() })
+
+for (i in 0..<25) {
+    val iter = stones.listIterator()
+
+    while (iter.hasNext()) {
+        val stone = iter.next()
+
+        if (stone == 0L) {
+            iter.set(1)
+        } else if ((log10(stone.toDouble()).toInt() + 1) % 2 == 0) {
+            val str = stone.toString()
+            iter.set(str.substring(0, str.length / 2).toLong())
+            iter.add(str.substring(str.length / 2, str.length).toLong())
+        } else {
+            iter.set(stone * 2024)
+        }
+    }
+}
+
+println("Result: ${stones.size}")

day11/part2.rs

@@ -0,0 +1,36 @@
+use std::collections::HashMap;
+
+fn main() {
+    let input = include_str!("input.txt");
+
+    let mut stones = input
+        .split(' ')
+        .map(|s| (s.parse::<u64>().unwrap(), 1u64))
+        .collect::<HashMap<u64, u64>>();
+
+    for _ in 1..=75 {
+        let mut new_stones = HashMap::<u64, u64>::new();
+        for stone in stones.keys() {
+            if *stone == 0 {
+                // Take all zeroes, and move them to ones
+                new_stones.insert(1, new_stones.get(&1).unwrap_or(&0) + stones[&0]);
+            } else {
+                let digits = stone.ilog10() + 1;
+                if digits % 2 == 0 {
+                    let new_rock = stone / 10u64.pow(digits / 2);
+                    new_stones.insert(new_rock, new_stones.get(&new_rock).unwrap_or(&0) + stones[stone]);
+
+                    let new_rock = stone % 10u64.pow(digits / 2);
+                    new_stones.insert(new_rock, new_stones.get(&new_rock).unwrap_or(&0) + stones[stone]);
+
+                } else {
+                    let new_rock = stone * 2024;
+                    new_stones.insert(new_rock, new_stones.get(&new_rock).unwrap_or(&0) + stones[stone]);
+                }
+            }
+        }
+        stones = new_stones;
+    }
+
+    println!("Result: {}", stones.into_values().sum::<u64>());
+}

flake.lock

@@ -34,10 +34,45 @@
         "type": "github"
       }
     },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1728538411,
+        "narHash": "sha256-f0SBJz1eZ2yOuKUr5CA9BHULGXVSn6miBuUWdTyhUhU=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "b69de56fac8c2b6f8fd27f2eca01dcda8e0a4221",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_2"
+      },
+      "locked": {
+        "lastModified": 1733884434,
+        "narHash": "sha256-8GXR9kC07dyOIshAyfZhG11xfvBRSZzYghnZ2weOKJU=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "d0483df44ddf0fd1985f564abccbe568e020ddf2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
       }
     },
     "systems": {

flake.nix

@@ -3,14 +3,22 @@
 
     inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     inputs.flake-utils.url = "github:numtide/flake-utils";
+    inputs.rust-overlay.url = "github:oxalica/rust-overlay";
 
-    outputs = { nixpkgs, flake-utils, ... }:
+    outputs = { nixpkgs, flake-utils, rust-overlay, ... }:
-        flake-utils.lib.eachDefaultSystem (system: let pkgs = nixpkgs.legacyPackages.${system}; in {
+        flake-utils.lib.eachDefaultSystem (system: let pkgs = import nixpkgs {
-            devShells.default = pkgs.mkShellNoCC {
+            inherit system;
+            overlays = [ rust-overlay.overlays.default ];
+        }; in {
+            devShells.default = pkgs.mkShell {
                 packages = with pkgs; [
                     deno
                     kotlin
                     libsecret
+                    (rust-bin.selectLatestNightlyWith (toolchain: toolchain.default.override {
+                        extensions = [ "rust-src" "rustfmt" ];
+                        targets = [ "x86_64-unknown-linux-gnu" ];
+                    }))
                 ];
             };
         });