From 0c39e2f0c67989c046c510da84c4e8caf76d8ffb Mon Sep 17 00:00:00 2001
From: Tristan <tristan@tristans.cloud>
Date: Mon, 16 Dec 2024 10:00:40 +0000
Subject: [PATCH] 2024 day 16 partially in nix

---
 2024/16/example.txt  | 15 ++++++++++++
 2024/16/example2.txt | 17 ++++++++++++++
 2024/16/solution.nix | 56 ++++++++++++++++++++++++++++++++++++++++++++
 2024/flake.lock      |  4 ++--
 2024/flake.nix       |  4 +++-
 5 files changed, 93 insertions(+), 3 deletions(-)
 create mode 100644 2024/16/example.txt
 create mode 100644 2024/16/example2.txt
 create mode 100644 2024/16/solution.nix

diff --git a/2024/16/example.txt b/2024/16/example.txt
new file mode 100644
index 0000000..2c21676
--- /dev/null
+++ b/2024/16/example.txt
@@ -0,0 +1,15 @@
+###############
+#.......#....E#
+#.#.###.#.###.#
+#.....#.#...#.#
+#.###.#####.#.#
+#.#.#.......#.#
+#.#.#####.###.#
+#...........#.#
+###.#.#####.#.#
+#...#.....#.#.#
+#.#.#.###.#.#.#
+#.....#...#.#.#
+#.###.#.#.#.#.#
+#S..#.....#...#
+###############
diff --git a/2024/16/example2.txt b/2024/16/example2.txt
new file mode 100644
index 0000000..bc61c57
--- /dev/null
+++ b/2024/16/example2.txt
@@ -0,0 +1,17 @@
+#################
+#...#...#...#..E#
+#.#.#.#.#.#.#.#.#
+#.#.#.#...#...#.#
+#.#.#.#.###.#.#.#
+#...#.#.#.....#.#
+#.#.#.#.#.#####.#
+#.#...#.#.#.....#
+#.#.#####.#.###.#
+#.#.#.......#...#
+#.#.###.#####.###
+#.#.#...#.....#.#
+#.#.#.#####.###.#
+#.#.#.........#.#
+#.#.#.#########.#
+#S#.............#
+#################
diff --git a/2024/16/solution.nix b/2024/16/solution.nix
new file mode 100644
index 0000000..6629304
--- /dev/null
+++ b/2024/16/solution.nix
@@ -0,0 +1,56 @@
+{lib, ...}: input: rec {
+  inherit lib;
+  inherit (lib) splitString mod;
+  inherit (lib.lists) findFirstIndex imap0;
+  inherit (lib.strings) stringToCharacters;
+  inherit (builtins) elemAt concatStringsSep length elem filter foldl' concatLists floor deepSeq;
+
+  index = i: list: elemAt list i;
+  index2d = {x, y}: m: m |> index y |> index x;
+
+  init = let
+    chart = input |> splitString "\n" |> map stringToCharacters;
+    width = (elemAt chart 0 |> length) + 1;
+    height = length chart;
+    startIndex = input |> stringToCharacters |> findFirstIndex (char: char == "S") null;
+    endIndex = input |> stringToCharacters |> findFirstIndex (char: char == "E") null;
+  in {
+    inherit chart width height;
+    pos = {
+      x = mod startIndex width;
+      y = startIndex / width;
+    };
+    goal = {
+      x = mod endIndex width;
+      y = endIndex / width;
+    };
+  }
+  ;
+
+  chartToStr = chart: chart |> (map (concatStringsSep "")) |> concatStringsSep "\n";
+
+  rotate' = {x, y}: {y = -x; x = y;};
+  rotate = {x, y}: {y = x; x = -y;};
+
+  addVec = a: b: {x = a.x or 0 + b.x or 0; y = a.y or 0 + b.y or 0;};
+  multVec = a: m: {x = a.x or 0 * m; y = a.y or 0 * m;};
+
+  minl = foldl' (a: e: if isNull a then e else if isNull e then a else if a < e then a else e) null;
+
+  search = {pos ? init.pos, dir ? {x = 1; y = 0;}, hist ? [], max ? null}:
+  let
+    fwd = search {pos = addVec pos dir; inherit dir; hist = hist ++ [{inherit pos dir;}];} |> add 1;
+    rot = search {inherit pos; dir = rotate dir; hist = hist ++ [{inherit pos dir;}]; max = fwd;} |> add 1000;
+    rot' = search {inherit pos; dir = rotate' dir; hist = hist ++ [{inherit pos dir;}]; max = fwd;} |> add 1000;
+    add = n: a: if isNull a then null else n + a;
+  in
+  if pos == init.goal then 0 else
+  if
+    elem {inherit pos dir;} hist ||
+    elem {inherit pos; dir = multVec dir (-1);} hist ||
+    index2d pos init.chart == "#" then null else
+  minl [fwd rot rot']
+  ;
+
+
+}
diff --git a/2024/flake.lock b/2024/flake.lock
index dd3f27c..fa45999 100644
--- a/2024/flake.lock
+++ b/2024/flake.lock
@@ -3,8 +3,8 @@
     "aoc-inputs": {
       "flake": false,
       "locked": {
-        "lastModified": 1734266579,
-        "narHash": "sha256-fhPoaCWITp2KZtdxm+D9e6GiWf+c3/RGJeiq03/ynfY=",
+        "lastModified": 1734334657,
+        "narHash": "sha256-NjsEC/6Mu+i94YPgK4yN0Y5TxhlWwXK5Ev2UzIkfGZo=",
         "path": "/tmp/aoc-inputs",
         "type": "path"
       },
diff --git a/2024/flake.nix b/2024/flake.nix
index ac43fc8..67dfb0b 100644
--- a/2024/flake.nix
+++ b/2024/flake.nix
@@ -25,16 +25,18 @@
     inherit (pkgs) lib;
 
 
-  in (lib.range 1 15
+  in (lib.range 1 25
   |> map (i: let id = lib.fixedWidthNumber 2 i; in {
     name = "day-${id}";
     value = let
       solution = import ./${id}/solution.nix pkgs;
       example = (pkgs.lib.readFile ./${id}/example.txt);
+      example2 = (pkgs.lib.readFile ./${id}/example2.txt);
       example3 = (pkgs.lib.readFile ./${id}/example3.txt);
       input = (pkgs.lib.readFile "${aoc-inputs}/${id}");
     in {
       example = solution example;
+      example2 = solution example2;
       example3 = solution example3;
       real = solution input;
       test = tix.run [