<!-- livebook:{"persist_outputs":true} -->

# Day 08

```elixir
Mix.install([
  {:kino_aoc, git: "https://github.com/ljgago/kino_aoc"}
])
```

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```
:ok
```

## Section

<!-- livebook:{"attrs":{"day":"8","session_secret":"ADVENT_OF_CODE_SESSION","variable":"puzzle_input","year":"2022"},"chunks":null,"kind":"Elixir.KinoAOC.HelperCell","livebook_object":"smart_cell"} -->

```elixir
{:ok, puzzle_input} =
  KinoAOC.download_puzzle("2022", "8", System.fetch_env!("LB_ADVENT_OF_CODE_SESSION"))
```

<!-- livebook:{"output":true} -->

```
{:ok,
 "404310113342042430523206553054613026452223317713352040314520532034136044035422242052404520323121423\n120022131035104020413264056552251024207112052153646716635163015540126546334604634352130343204203212\n114444043404350333465355412140536532335724647116565610572546474626506052303052063065052530351012030\n212240414554223531015555065165021520410363021033163304514155663733352116600665403462501544352500033\n324144130111224105125305614015103771206061460425505011635353313773273343325122626415203015344311232\n113245430241150240464126012614135430370003075735010164413125456766205302613425655024334411031155403\n441245002130523346005210411662277072426351216071200446765701447237330324567025204602342520044502121\n214045553122025654652221354616163561012500762010384874262074144065234401637722263412266464251452314\n420554052436551160102504245073471242400253801258004372606111667766236046654353552356241642235535400\n230444034403653045355316273427144521155460537330375254634265217831710133466511570022515061342332314\n215330305636623403455371527067601715250678103470620507380025232122252031461570076036342312211025412\n152531154664324333510065716166433534816054420634864077383448250450766671674224724566465113516230555\n214332343546262452365454705617472281546633211772075171047360414071436550632720021764434561305210301\n111443005611044613477737043746056557178022072372401206038184673647422320773366100676006211551510212\n133313521334520014277727658110473505777283286103991788280475205774027243280366061162025220015443455\n155404252050544375401645717463634684248661783289138494563725362778686756122861113531553244022156404\n101264441110131756443257557872335606716942314559648922296471179061870856246756574324520340610552502\n552345216103355364312158072306454410946149736569151493634487672710443362287688034427626033035266435\n032116136355447236216431376728258285654613995348237354962282338329733408310145842020562245054642441\n224363655451243141363087456580326751652471257429153117112342588642859256252141665722503521125022565\n203656402177710126565314466702484652152875481365818345352121487714962821315157703464343750046056642\n556042122224622324270101114885994351144861589211656115175234527658398149331284812500044434453264665\n333402317273401421323318415855844499641764213948757537893227517242385296970317342824206711503004500\n341045445002443367084450562962259886574728664877676766689484955395194385797583863611332250124025511\n530441155216276525375870173389743919985448259629562325456237285529598688811050240824703721074602060\n320021441136216827813607342916845194696625696785568454728524752386544154132864251748117643644612016\n356236015127477502168551236473444979246675949449587984562945859468987964451443376640177554302403555\n521032161450418348764563917129159623593365988455562286236885389659621188427923285451742156213351116\n161327255665606701821864175493119539272489637754729983857664245665796727199928145136462257620362465\n324256011240774073378929732467468357478524626995373968674237767743387885552216853467388044247756643\n342275312602047038565615877434724873572784389557789777857693948752846554139723438258054200025014665\n051242516637708146638198373275222758924486548779744574439965559638384373152521363134036477637737533\n643152555635778437871298236855485688298578349488385645847564753765967563925377954286572876073532255\n052252355510464443878597562686999366353446874577654743895687373779864325297372128203202721414431575\n003626454683627045725543215594452394956436955758673339474559874959389629573279978978206522053161354\n627516237702078544682942119397343558584845947957956986767739349699889797692213624665730454802067156\n200457151510133551651137637224323537736454384779467644967339586954746668462789875763614758041306350\n335154370506881211537946276895249658859666595888979499974679997597784647296794417997582782381025574\n417013603706282285595672445598476844553485594594694865577988599545878778554434654896767653370600163\n151076753567166396584462282676939868463579768879699478585698835334464668886671938943507604626741055\n316424603540766436474549593426596456855354984858479546978868766769885893482223982736645038024543" <> ...}
```

```elixir
surroundings = %{top: 0, lft: 0, rig: 0, bot: 0}

# puzzle_input ="""
# 30373
# 25512
# 65332
# 33549
# 35390
# """

raw_map =
  puzzle_input
  |> String.split("\n", trim: true)
  |> Enum.with_index()
  |> Enum.flat_map(fn {line, row} ->
    line
    |> String.to_charlist()
    |> Enum.with_index()
    |> Enum.map(fn {v, col} -> {{row, col}, v - ?0} end)
  end)
  |> Map.new()

{height, width} = Enum.max(Map.keys(raw_map))
```

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```
{98, 98}
```

## Task 1

```elixir
defmodule Task1 do
  def get_max(map, where, p) do
    case map[pos(where, p)] do
      nil -> -1
      {curr, %{^where => max}} -> max(curr, max)
      curr when is_integer(curr) -> curr
    end
  end

  defp pos(:top, {x, y}), do: {x - 1, y}
  defp pos(:bot, {x, y}), do: {x + 1, y}
  defp pos(:lft, {x, y}), do: {x, y - 1}
  defp pos(:rig, {x, y}), do: {x, y + 1}
end
```

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```
{:module, Task1, <<70, 79, 82, 49, 0, 0, 9, ...>>, {:pos, 2}}
```

```elixir
lt_map =
  for x <- 0..height,
      y <- 0..width,
      reduce: raw_map do
    map ->
      v =
        case map[{x, y}] do
          {v, _} -> v
          v -> v
        end

      top = Task1.get_max(map, :top, {x, y})
      lft = Task1.get_max(map, :lft, {x, y})

      %{
        map
        | {x, y} =>
            {v,
             %{
               top: top,
               bot: -1,
               lft: lft,
               rig: -1
             }}
      }
  end

map =
  for x <- height..0//-1,
      y <- width..0//-1,
      reduce: lt_map do
    map ->
      {v, maxes} = map[{x, y}]

      bot = Task1.get_max(map, :bot, {x, y})
      rig = Task1.get_max(map, :rig, {x, y})

      %{
        map
        | {x, y} => {v, %{maxes | bot: bot, rig: rig}}
      }
  end
```

<!-- livebook:{"output":true} -->

```
%{
  {76, 13} => {7, %{bot: 7, lft: 7, rig: 9, top: 8}},
  {37, 47} => {8, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {65, 63} => {4, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {38, 2} => {7, %{bot: 7, lft: 4, rig: 9, top: 7}},
  {1, 26} => {6, %{bot: 9, lft: 6, rig: 7, top: 3}},
  {83, 76} => {8, %{bot: 7, lft: 9, rig: 7, top: 9}},
  {32, 15} => {4, %{bot: 8, lft: 8, rig: 9, top: 8}},
  {89, 14} => {0, %{bot: 4, lft: 6, rig: 8, top: 8}},
  {35, 30} => {3, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {37, 53} => {9, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {4, 5} => {4, %{bot: 7, lft: 4, rig: 7, top: 4}},
  {8, 50} => {4, %{bot: 9, lft: 8, rig: 7, top: 6}},
  {78, 98} => {6, %{bot: 6, lft: 9, rig: -1, top: 7}},
  {95, 56} => {5, %{bot: 5, lft: 7, rig: 7, top: 9}},
  {74, 12} => {1, %{bot: 6, lft: 7, rig: 9, top: 8}},
  {11, 39} => {0, %{bot: 9, lft: 8, rig: 8, top: 7}},
  {65, 43} => {6, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {22, 38} => {1, %{bot: 9, lft: 9, rig: 9, top: 8}},
  {14, 86} => {5, %{bot: 8, lft: 9, rig: 5, top: 6}},
  {20, 41} => {5, %{bot: 9, lft: 8, rig: 9, top: 9}},
  {29, 25} => {3, %{bot: 9, lft: 9, rig: 9, top: 7}},
  {86, 10} => {3, %{bot: 5, lft: 6, rig: 8, top: 8}},
  {83, 36} => {5, %{bot: 8, lft: 7, rig: 9, top: 9}},
  {29, 26} => {2, %{bot: 9, lft: 9, rig: 9, top: 8}},
  {47, 27} => {3, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {4, 81} => {4, %{bot: 9, lft: 7, rig: 5, top: 4}},
  {31, 42} => {5, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {9, 34} => {2, %{bot: 9, lft: 7, rig: 8, top: 7}},
  {90, 0} => {4, %{bot: 4, lft: -1, rig: 8, top: 7}},
  {67, 98} => {1, %{bot: 6, lft: 9, rig: -1, top: 7}},
  {13, 85} => {0, %{bot: 9, lft: 8, rig: 6, top: 6}},
  {63, 81} => {9, %{bot: 7, lft: 9, rig: 8, top: 9}},
  {82, 60} => {6, %{bot: 8, lft: 9, rig: 9, top: 9}},
  {47, 38} => {4, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {15, 92} => {2, %{bot: 7, lft: 9, rig: 6, top: 6}},
  {58, 58} => {8, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {20, 3} => {6, %{bot: 7, lft: 3, rig: 9, top: 5}},
  {61, 95} => {3, %{bot: 7, lft: 9, rig: 7, top: 7}},
  {23, 67} => {9, %{bot: 9, lft: 9, rig: 9, top: 9}},
  {78, 75} => {1, %{bot: 6, lft: 9, rig: 7, top: 9}},
  {79, 17} => {6, %{bot: 6, lft: 7, rig: 9, top: 9}},
  {75, 0} => {5, %{bot: 6, lft: -1, rig: 9, top: 7}},
  {16, 73} => {4, %{bot: 9, lft: 9, rig: 7, top: 8}},
  {76, 2} => {3, %{bot: 6, lft: 4, rig: 9, top: 7}},
  {58, 84} => {9, %{bot: 8, lft: 9, rig: 6, ...}},
  {58, 33} => {6, %{bot: 9, lft: 9, ...}},
  {47, 44} => {5, %{bot: 9, ...}},
  {54, 31} => {9, %{...}},
  {13, ...} => {3, ...},
  {...} => {...},
  ...
}
```

```elixir
map
|> Enum.count(fn {_, {v, maxes}} ->
  maxes
  |> Map.values()
  |> Enum.any?(&(v > &1))
end)
```

<!-- livebook:{"output":true} -->

```
1538
```

## Task 2

```elixir
defmodule Task2 do
  def range(range, value) do
    Map.new(range, &{&1, value})
  end
end
```

<!-- livebook:{"output":true} -->

```
{:module, Task2, <<70, 79, 82, 49, 0, 0, 6, ...>>, {:range, 2}}
```

```elixir
empty = Task2.range(0..9, 0)

l_map =
  Enum.flat_map(0..width, fn x ->
    {list, _} =
      Enum.map_reduce(0..height, empty, fn y, acc ->
        # IO.inspect({{x, y}, acc})
        v = raw_map[{x, y}]
        dist = y - acc[v]
        new_acc = Map.merge(acc, Task2.range(0..v, y))

        {{{x, y}, dist}, new_acc}
      end)

    list
  end)
  |> Map.new()

t_map =
  Enum.flat_map(0..width, fn y ->
    {list, _} =
      Enum.map_reduce(0..height, empty, fn x, acc ->
        v = raw_map[{x, y}]
        dist = x - acc[v]
        new_acc = Map.merge(acc, Task2.range(0..v, x))

        {{{x, y}, dist}, new_acc}
      end)

    list
  end)
  |> Map.new()

empty = Task2.range(0..9, width)

r_map =
  Enum.flat_map(height..0//-1, fn x ->
    {list, _} =
      Enum.map_reduce(width..0//-1, empty, fn y, acc ->
        v = raw_map[{x, y}]
        dist = acc[v] - y
        new_acc = Map.merge(acc, Task2.range(0..v, y))

        {{{x, y}, dist}, new_acc}
      end)

    list
  end)
  |> Map.new()

b_map =
  Enum.flat_map(width..0//-1, fn y ->
    {list, _} =
      Enum.map_reduce(height..0//-1, empty, fn x, acc ->
        v = raw_map[{x, y}]
        dist = acc[v] - x
        new_acc = Map.merge(acc, Task2.range(0..v, x))

        {{{x, y}, dist}, new_acc}
      end)

    list
  end)
  |> Map.new()

merger = fn _, a, b -> a * b end

l_map
|> Map.merge(t_map, merger)
|> Map.merge(r_map, merger)
|> Map.merge(b_map, merger)
|> Enum.max_by(&elem(&1, 1))
```

<!-- livebook:{"output":true} -->

```
{{9, 63}, 496125}
```

```elixir
{l_map[{3, 2}], t_map[{3, 2}], b_map[{3, 2}], r_map[{3, 2}]}
```

<!-- livebook:{"output":true} -->

```
{2, 1, 1, 1}
```