Day 1

.envrc

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+use flake

.gitignore

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+.bloop/
+.direnv/
+.metals/
+.vscode/
+.bsp/
+out/

.scalafmt.conf

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+version = "3.0.5"
+runner.dialect = scala3

aoc/src/Day1.scala

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+import scala.io.Source
+
+object Day1 extends App:
+
+  val calories = Source
+    .fromURL(getClass.getResource("day1Input.txt"))
+    .mkString
+    .split('\n')
+    .toList
+
+  val elvesCalories = calories
+    .foldLeft(List(0)) {
+      case (elvesTotal, caloriesValue) if caloriesValue.isEmpty =>
+        0 :: elvesTotal
+      case (elfTotal :: elveTotal, caloriesValue) =>
+        caloriesValue.toInt + elfTotal :: elveTotal
+    }
+
+  println(s"Part 1: ${elvesCalories.max}")
+
+  val top3ElvesCalories = elvesCalories.sorted.takeRight(3).sum
+
+  println(s"Part 2: ${top3ElvesCalories}")

build.sc

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+import mill._, scalalib._
+
+object aoc extends ScalaModule {
+  def scalaVersion = "3.2.1"
+}

flake.lock

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+{
+  "nodes": {
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1668681692,
+        "narHash": "sha256-Ht91NGdewz8IQLtWZ9LCeNXMSXHUss+9COoqu6JLmXU=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "009399224d5e398d03b22badca40a37ac85412a1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1669791787,
+        "narHash": "sha256-KBfoA2fOI5+wCrm7PR+j7jHqXeTkVRPQ0m5fcKchyuU=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "e76c78d20685a043d23f5f9e0ccd2203997f1fb1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+
+        millWithFixedJdk = pkgs.mill.override { jre = pkgs.jdk; };
+      in
+      {
+        devShell = pkgs.mkShell {
+          buildInputs = [ millWithFixedJdk ];
+          shellHook = ''
+            set -a
+            JAVA_HOME=${pkgs.jdk}
+            set +a
+          '';
+        };
+      }
+    );
+}

shell.nix

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+(import
+  (
+    let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
+    fetchTarball {
+      url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+      sha256 = lock.nodes.flake-compat.locked.narHash;
+    }
+  )
+  { src = ./.; }
+).shellNix