2024 day 6 part 2 (but very slow)

2024/06/annotated.txt

@@ -0,0 +1,130 @@
+..........#.............................#...............#...........#....................#...........#............................
+..............................#.......#...#.....#.....#...............#.#..#.......................#............#.................
+.............#...........#.#........#............#..........................#.........#.......#......#............................
+......................................................#....#..#.............#................................#...#............##..
+...............#.....#....................................#.................O.OOO...OOO.OO.........O..OO.........#................
+..................##............#......#..................O.O.......O..OOO...O.OO...OO..OO.........O...#...................#......
+.#......#...........OO..OOO...O......O...O.OOO..O.OO..OO....O.......#............................#................................
+#..#.............#...............................#.....#....#.............................#....#..............................#...
+#...##..........#.........................#.................................................#............#...............#........
+............#...............#.............................O................#.......................OO..O.....#..........##........
+..............#...................#......##...#.....#.....O..............#..O...............O....................................#
+.#.....#....#......................#...#..O..O..O.....O.....................O..O#.#.............#.........#.......................
+#..#..............O#........##.........#.....#..........#.....##............O............#..O..#.#................................
+...............#..O............................#.....#....O.................O..........................#..##......................
+......#...........O.......#..........#...................O..O..........O.O..O...O#....#.....O.....................................
+.............................................O.#...#....##.................................................#.....#................
+.................#.........#..............................#........#...#...#...OOO...O..O.....O.O.O...O.....O..#..................
+...........#..#...O.#...#.....................O...#..........#.#.............#....#...................##....O...O.................
+.................O.......O...............#....O......O.............#.#............#...#...##..O.O.......................#.........
+.....#............O.........................#.O.......................OO.O..O...O...OO.......O...#..........O...#.................
+..................O.....................O.....O...#..O.............O.#..........O.....#.............#.#..#..................#.....
+............................................#.....#..O...................#........#..........................................#....
+.......#..........O...............#...#.......OO...O.....O..O.......O.OO.O#.........................#...#..........#......#.......
+............#.....O.....##.........O.....O...O.....O................O.............................#......................#........
+#.#..............O...........O.......O..OOO..OOO..#........#.......O..#.#O.#...#O...............O...............#.................
+..#.........O.O...O.........#.#...........O.O........O.#....##.....O..O..O.....OO...OO.......O...........O.OO...#............#....
+....................................................................O.OO.......O.....#...............#......O....#..........#.....
+..............O...O.#..........#................................#...............................................#.................
+#...........O..#.#O..........#.........#..........#...................O......#......................##........#.........#.........
+....#....#..O.....O.....................O...................O......O..O..................#...#...........#............#...#...#...
+........................................O.....O..O.....##................O.....#O..#................................#.............
+.......#..........O##.....................O.O...#....O......O..#...O..O.......................#...................#......#........
+......#.........#.O.................................................O..O.......#........#..#..........#.....O.#..#...#.....#....#.
+....#.............O..............................O#........#....#..................................#..............................
+..........#.O.O..#O..........#...................O...O............#..............#.......#...#............#.O..O..................
+............O................O..O............OOO...O..O....O........O..O.OO....O.....O.O..O#....O..#..............................
+.#................O.................................#O.............O..O...........#..................#......O..O.........#........
+......#..#.#......O.........#...........O.....O..O#..O..........................O....#.............#...............#..............
+...................O....O...O..#........O...O....O#..O.....#.......O..O.....................................O..O..................
+......................#.............................................O.OO.O.....O....OO....O.O.OO......O..#..O..O...#..............
+...............................................................................................................................#..
+.......#.O........O...#............................................O..O...........#......................#.......................#
+#........O........O.............#...........O..................#...O..O#..........O..O......O.........#...#...#........#..........
+............................#....#...#.........#....#.....OOO.O..OO.OO.O.OO.O...OO......O.O.....O....................#............
+.........OO.O.O...O..#...........O.............O.....OO....O....O...O.OOO.O....O..O..O.#..#....#............O.....#...............
+.........OO.O.O...O...#.......O.....#............O................#.OOOO..O......OO..........O...O.O.....O...O........#...........
+....#.............O...#.#.........##O...OOO.OOOOOOO.#.....#...........O..O......O.....O.........O...........O..#.............#....
+..............................O#...#....O.....O..O.....#........O...O.OOOO.....O.....O......O.O#O.....#.O...O.....................
+....#..............................................O..............................................................................
+...#...............O..OOO...O.OO.O.OO..O.OOOOOOOOOOOOOOOOOO.OO.OO.OOO.OOOOOO.OOOOO..OOOOO.O.OOOOOO..O.OO.OO#O...........#.......#.
+..#.O....OO.O.O.##OOOO.OOOOO..O....................O...........................#...#........................O...#............#....
+....O....O............#.......#............#OO.O.O.O.....O.O..O..OO.OO.O..O......O....O..O...O......#..................#......#...
+....O..............#.............#..O............OOO#.................O..O......O..#..O.........#........#O.O................#....
+....................#O..........#...O..........O................O...O.OOOO.....OO....O..O.#......#.......#O.O........#.....##.....
+....O....OO#O.O.........................O........O.O.#..........................O..#..O...........#.......O.O........#............
+......................#.........#................O.O#......#...........................................#..........................
+..#.O..#...#OO.O.........O.O....O...O...O#.......O.O....#................O....#.O...O.O..O.#..O......O..O......................#..
+....O#.O.O....O....O..OOO......O..O#O...#.....O..O.O.......................#...................#...#......O.O....#................
+..............O....#...#...........#O..............O........#.............#........................#...#O.O.O........#..........#.
+...#O..O.OO...O#O.....#O....O.#...O.O........#....OO#.....O....#.....#O......O..OO....O...O..O.OO..O....O.........................
+..#..................O............O.....O......O......O..#......#........O......O.....O.....#...........#.O.O..#..#...............
+........#...................O.O..O..O#.#..........O.......O.#...#...#......#.....#O.......................O.O....................#
+....O..O.OO..#O.O.#....O...#OOO..OO.OO.........O................O...OO.O.O...........O........O.OO..O.....O.O........#.........#..
+..................................O............O................O...OO.O........O....O..........OO..#.....O.O.....................
+..#.O..................O...#....#...O.O..O...O.O.........O.OO.OO.O.OO.O...O..O..OO....O...O...............O.O#....................
+.....................O.......O....O.O..#.....#.#.O.O....O................O......O.....O#.O....#........#.#O.O.......O........#....
+.................#.....O..#.........O............O.O....O......#...#..#..O......O...O.O................#....O.......O.............
+....O..O.OO#..O......O.O.....O...........................................O......O.....O..O...........O.......#....................
+......................#......O....O.O....#...#...O.O.......#................##................#.......#...O.O.....#.O.......#.....
+....O.......#..#.............O..#...O.........O..OOO....O.O..............O....#.O.O...O..O.##.............O.O..##..........#......
+....O.#.#............O.O.....O..#.O..........#...OOO....O.O..............O........O......................#..........O.............
+#.....................O.O..O.....OOO...#.#.....O^O.O........O...................O.....O..O......#..O.O....O.O.......O.............
+......OO#O..OO.O.O..O..OO..O.O..OOO.O.OO.O.OOOOO.O.O....O...........#....O......O...#.O..O...........O....O.O.......O.............
+...#OO..OO..OO.O.O.OO.O.OOOO.O....O...O..........#.O...............#.....O......O..#.............................#...#.#..........
+....................#........#...........##........O..............#......O......O...#..................#................#.........
+#.............O.O......O....O.O...O.OOO...........OO......O.......................O...............................................
+............#..........O....O.O.....O.............O.......O.........................................#.#.........#..............#..
+...............#....#O...........#O...O............O....O................O......O...#.O..O.##......O.OOO.O.O.OOOO....OO...OOO.#...
+......OO..O...O.O....O.O....O#O...O.O.O#......O...OO...#..O...#.......#...........O.....#...........O............#........#.......
+.......................O..........O...O...........OO..#...O..............O......O.O...O.O......OO...OO.O..O.O.O#.................#
+.......O..O...O..#.#...O...........#O.OO...OOO.O.OOO..OO.OOOOOOO..O.OOOOO.OO.OOO.OO....OO....O..OO..O....OO...............#..O.#..
+......OO#.O...O.......#O..............O......#....OO.....#...........#....................................O.#..............#......
+......O.........O.....#O....O.O..............#....OO....O#O....#.....##..O......O.....O..O..........OO....O........#....#.........
+.............#.O.O.....O...O.O....O.O.O....OOO.O.O.O.OOOOO.OOO.O..O..OOO.OO..O..O.O...O.OO....#.....OO...#O...O#....O.............
+......OO..O.##..O......O....O.O...O...O..#........OO......O................#..#.#...................O.........O......#.......O....
+......OO..O............O..........O...O........O..O.......O..........O...O......O.............#......O....O...O.....O......#.O....
+...#...O...............O.........#..#..#....................................#..............#....#.................................
+.....#O.OO.OOO.O.O..O..OOO.O.O........O............O............#.....#......#....O....#O...........OO....O...O.....O........O....
+....##......#.....................#...O......#..............#............O.....#.#....O..O...O..#...OO...#O...O......#....#..O....
+.....#.O.#......O.O#.O.O....O.O.#....OO..O...#....OO....O................O............O..O...O......OO....O#..O.....O.............
+.......O.#O.O..O.O....................O......#....OO....O#O..............O........O...O..O...O.##..OOO#...O...O....#..............
+.....##.#............##OOOOO.O.OOOOOO.O.....#......O....O..............#.O............O..O..........OO...#........#..........O....
+.......................#..............##...#......OO....O.O..............O........O...O........#....O....#O...O...................
+..#....O...#.......#...#..##............#...OO.O...O.OO.....OO...................O....OOO....OOOO....O....O..#O.....O....#...O.#..
+..#.............O.O........O.........O.OO.O..OOO.OOOOOO.OOO..O..OOO..OOO#O........O...O#.O...O......O#....O.........O....#........
+...........#....O.O...#O......O..#.....#..........O.......O..............................O...O...........#O.#.....................
+.......O..#.....O.O....O...#OOOO....OOO.O.O.OO.O.O.O.OOO.O..OOOO..O.OO.O............##.#.....O..O........O...OO........#.#......#.
+#............................................#.....O...................O.##...#..........OO..OO......O#...O...O.....#.............
+..#....O.......#.O...O.O..OOOO.OO...O.O.O.O.OO.O.O.O.OOOOO..OOOO..O.OO.O..OOOO.O.OO.....................................#.........
+.......O...........................................O#..................O.#............#..............O#...O......................#
+........................................................................#.......#....................O...O.OOO.O.OO.OO#.#.........
+................#..#......................#...........................................#OO..O.OOOOO.O.....OO..OOO.....O............
+.......O................##.........................O....O.............#O............##...............O..........#....O..#....#....
+.........#.......#...O.O..O....O................#......#....#..........O.#..................#...#...O.O...........................
+#......O..#............O...............#....#.#..#...OO................O............................OOO...O##.O......O............
+.#..##.O.............#.O..#...................O.O.OOO.O.#..............O#........#.....O.....OO.O...O....O...............#......#.
+...#......................O............O......O...OOO.O.........#......O..............#..O...O.......OO.#.O...#......O............
+...#...........#..#.............................#.....#.................................O.O...O..O...OO....O.O......#O............
+...#.........................#.OO...O...O.O..........O.OOO..OOO...O.O.....O......O.....O.............O....O..........O......##....
+.........................#.........................O.#.O.......O.......O.....#...........#...........O....O........O.O............
+.#..................................#.......................O................................O........O...........................
+..............................................O....O...O.......O....#..O........##.....#.#...O.....#.O...#O........O.O............
+.......O........#...............................#........#..OOO...O.O.....O......O.....O.............OO............O.O............
+......#....#...........O.....................#O..O.....OOOO.OOOO..O.OO.O.........#.#.........#.....#O.....O........O.O..#.........
+................#..............................#.......O...............#...#.....#.......#...........O....#........O.O............
+....................#O....OO.O.OOOO.O...O.O...O..O.........#..#...........#.#.................#...#................O.O....#.......
+.......O.....#..#...#............................#.#...O..............................O........#......O..............O.#..........
+.........#..........#.................#................O...................#.#.......................O.............O.O..#.........
+....#.............#.......................O....OOO.O..OOO.......OOO...O.O#...........#.O...O..OOO..O..O..........#...O............
+.......O#.#............................#...........................................#.................#O.............#..........#..
+..............#..........................#............#O........#....#..O#.....#......................O..#....#.....OOO.OO....##..
+...................#OOO..OOO.O.OOOO.O..OOOOOOO...O.O...O................O....#.......#........#..............#.....O.O..#.........
+.#.....O..#....#.......O..........................#..#.#...............#O...........#...........#..................O.O............
+...............................................................O........O......................#.....#....#........O.O..#....O....
+...........#..........#..OOO.O.OOOO.O.....O.O....O..O.OO.O..O.....#.........#..............#................#......OOO.#..........
+............#.................................###..............#.#......O...........................................O............#
+......#O.O....O.O..OO.OO.OOOOO.OOOO.OO.O.OOOOO...O.OO.OO.O..O.O...O..OO...................#............#...#........O.#.....#.....
+.............#..................#...................#......#.........#..#.......................#....#.OO.O..OO.O.....#......O...#
+..#....##................................#.................#...........................#.......#....#...#..........#.O............
+...............................#......................................#.........#.............#......................#.......O..#.

2024/06/solution.nix

@@ -2,10 +2,11 @@
 
   content = lib.trim input;
 
-  chart = content
+  chart = toChart content;
+
+  toChart = s: s
     |> lib.strings.splitString "\n"
-    |> map (lib.strings.splitString "")
+    |> map (lib.stringToCharacters)
-    |> map (line: lib.sublist 1 (builtins.length line - 2) line)
   ;
 
   startingPos = let
@@ -22,7 +23,7 @@
 
   index = i: list: builtins.elemAt list i;
 
-  getChar = {x, y}: chart
+  getChar = {x, y}: chart: chart
     |> index y
     |> index x
   ;
@@ -30,33 +31,101 @@
   height = builtins.length chart;
   width = chart |> index 0 |> builtins.length;
 
-  progress = {visited ? {}, pos, dir, ...}: let
+  replace2d = {x, y}: updated: chart: let
-    nextChar = getChar (addVec pos dir);
+    newRow = chart |> index y |> replace x updated;
-    newDir = if nextChar == "#"  then rotate dir else dir;
+  in
+    replace y newRow chart;
+
+  replace = i: updated: list: 
+  let before = lib.sublist 0 i list;
+    after = lib.sublist (i + 1) (builtins.length list - i) list;
+  in
+    if i < 0 || i > builtins.length list then list else
+    before ++ [updated] ++ after;
+
+  progress = {visited ? {}, pos, dir, obs ? [], charts ? chart, ...}: let
+    newDir = if colliding then rotate dir else dir;
     newPos = addVec pos newDir;
+    colliding = nextChar == "#";
+    nextChar = getChar fwd charts;
     fwd = addVec pos dir;
+    hash = posToString pos;
+    exited = fwd.y >= height || fwd.x >= width || fwd.y < 0 || fwd.x < 0;
+    canObstruct = 
+      # unique
+      (!lib.elem (posToString fwd) obs)
+      # inside map
+      && (!exited)
+      # can't put an obstacle when there already is one
+      && (!colliding)
+      # if I already visited the place in front, putting an obstacle there won't work, as I can't get to where I am now!
+      && (!lib.hasAttr (posToString fwd) visited)
+      # see if I will end up in a loop turning right here
+      && getLoop {inherit pos visited dir; charts = replace2d fwd "#" charts;};
   in
   {
-    visited = visited // {${posToString pos} = true;};
+    visited = visited // {${hash} = visited.${hash} or [] ++ [dir];};
-    exited = fwd.y >= height || fwd.x >= width || fwd.y < 0 || fwd.x < 0;
+    pos = if colliding then pos else newPos;
-    pos = newPos;
     dir = newDir;
+    inherit exited charts;
+    obs = obs ++ (if canObstruct then [(posToString fwd)] else []);
   };
 
   rotate = {x, y}: {x = -y; y = x;};
 
   startingDir = {x = 0; y = -1;};
 
-  getVisits = {pos ? startingPos, dir ? startingDir, visited ? {}, ...}:
+  getVisits = {pos ? startingPos
+  , dir ? startingDir
+  , visited ? {}
+  , obs ? []
+  , charts ? chart
+  , ...}:
     let
-      nextStep = progress {inherit pos dir visited;};
+      nextStep = progress {inherit pos dir visited obs charts;};
-    in if nextStep.exited then visited else getVisits nextStep;
+    in if nextStep.exited then nextStep else getVisits nextStep;
 
-  part1result = getVisits {}
+  path = getVisits {};
+
+  part1result = path.visited
     |> builtins.attrNames
     |> builtins.length
-    # the last position
-    |> (v: v + 1)
   ;
 
+  getLoop = state:
+    let
+      nextStep = progress state;
+      hash = posToString state.pos;
+      enteredLoop = lib.elem state.dir (state.visited.${hash} or []);
+    in if enteredLoop then true
+      else if nextStep.exited then false
+        else getLoop nextStep;
+
+  part2result = builtins.trace "This is very slow!" (path.obs |> builtins.length)
+  ;
+
+  # visualisation stuff
+
+  hashToVec = s: s |> lib.splitString "," |> map lib.strings.toInt |> (v: {x = index 0 v; y = index 1 v;});
+
+  annotateObs = chart:
+    builtins.foldl'
+    (c: obs: let pos = hashToVec obs; in replace2d pos "O" c) chart path.obs;
+
+  annotatePath = chart:
+    builtins.foldl'
+    (c: hash: let
+      pos = hashToVec hash;
+      dir = index 0 path.visited.${hash};
+      sym = if dir.x == 1 then ">" else if dir.x == -1 then "<" else if dir.y == 1 then "v" else "^";
+    in replace2d pos sym c) chart
+    (builtins.attrNames path.visited);
+
+  chartToStr = c: c
+    |> map (lib.concatStringsSep "")
+    |> lib.concatStringsSep "\n"
+  ;
+
+  annotated = chart |> annotatePath |> annotateObs |> chartToStr;
+
 }

2024/flake.nix

@@ -15,8 +15,19 @@
       example = (pkgs.lib.readFile ./06/example.txt);
       input = (pkgs.lib.readFile ./06/input.txt);
     in {
-      part1example = (solution example);
+      example = (solution example);
-      part1 = (solution input);
+      sample1 = (solution ''
+.#..
+.^#.
+.#..'');
+      sample2 = (solution ''
+.#......
+........
+.....#..
+#.......
+..#.#...
+...^....'');
+      real = (solution input);
     };
 
     packages.x86_64-linux.watch = tix.watch {