commit 6edffc467cea1f2bcc3e50a4d49619c08a261e95 · hauleth.dev/advent-of-code

+1 -1

2022/day07.livemd

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       ```elixir

     

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       max = 70_000_000

     

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       -
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       {current, _} = fs

     

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       needed = 30_000_000

     

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       left =

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2022/day08.livemd

···

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

     

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       # Day 08

     

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       ```elixir

     

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       Mix.install([

     

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         {:kino_aoc, git: "https://github.com/ljgago/kino_aoc"}

     

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       ])

     

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       ```

     

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

     

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       ```

     

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       :ok

     

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       ```

     

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       ## Section

     

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

     

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       ```elixir

     

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       {:ok, puzzle_input} =

     

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         KinoAOC.download_puzzle("2022", "8", System.fetch_env!("LB_ADVENT_OF_CODE_SESSION"))

     

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       ```

     

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

     

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       ```

     

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       {:ok,

     

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        "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" <> ...}

     

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       ```

     

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       +
       

     

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       +
       ```elixir

     

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

     

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       +
       

     

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       # puzzle_input ="""

     

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       # 30373

     

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       # 25512

     

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       # 65332

     

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       # 33549

     

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       # 35390

     

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       # """

     

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       +
       

     

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       raw_map =

     

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         puzzle_input

     

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         |> String.split("\n", trim: true)

     

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         |> Enum.with_index()

     

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         |> Enum.flat_map(fn {line, row} ->

     

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           line

     

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           |> String.to_charlist()

     

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           |> Enum.with_index()

     

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           |> Enum.map(fn {v, col} -> {{row, col}, v - ?0} end)

     

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       +
         end)

     

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       +
         |> Map.new()

     

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       +
       

     

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

     

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       +
       ```

     

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

     

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       +
       

     

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       ```

     

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       {98, 98}

     

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       +
       ```

     

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       +
       

     

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       ## Task 1

     

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       +
       

     

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       +
       ```elixir

     

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       defmodule Task1 do

     

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         def get_max(map, where, p) do

     

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           case map[pos(where, p)] do

     

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             nil -> -1

     

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             {curr, %{^where => max}} -> max(curr, max)

     

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             curr when is_integer(curr) -> curr

     

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           end

     

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         end

     

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         defp pos(:top, {x, y}), do: {x - 1, y}

     

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         defp pos(:bot, {x, y}), do: {x + 1, y}

     

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         defp pos(:lft, {x, y}), do: {x, y - 1}

     

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         defp pos(:rig, {x, y}), do: {x, y + 1}

     

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       end

     

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       ```

     

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

     

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       +
       

     

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       ```

     

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

     

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       +
       ```

     

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       +
       

     

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       +
       ```elixir

     

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       +
       lt_map =

     

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         for x <- 0..height,

     

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             y <- 0..width,

     

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             reduce: raw_map do

     

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           map ->

     

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             v =

     

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               case map[{x, y}] do

     

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                 {v, _} -> v

     

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                 v -> v

     

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               end

     

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

     

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

     

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             %{

     

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               map

     

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               | {x, y} =>

     

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                   {v,

     

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                    %{

     

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                      top: top,

     

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                      bot: -1,

     

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                      lft: lft,

     

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                      rig: -1

     

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                    }}

     

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             }

     

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         end

     

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       +
       

     

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       map =

     

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         for x <- height..0//-1,

     

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             y <- width..0//-1,

     

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             reduce: lt_map do

     

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           map ->

     

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             {v, maxes} = map[{x, y}]

     

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       +
       

     

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

     

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

     

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       +
       

     

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             %{

     

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               map

     

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

     

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             }

     

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         end

     

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       ```

     

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       +
       

     

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

     

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       +
       

     

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       +
       ```

     

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       +
       %{

     

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       +
         {76, 13} => {7, %{bot: 7, lft: 7, rig: 9, top: 8}},

     

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       +
         {37, 47} => {8, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       141
       141
       +
         {65, 63} => {4, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       142
       142
       +
         {38, 2} => {7, %{bot: 7, lft: 4, rig: 9, top: 7}},

     

       143
       143
       +
         {1, 26} => {6, %{bot: 9, lft: 6, rig: 7, top: 3}},

     

       144
       144
       +
         {83, 76} => {8, %{bot: 7, lft: 9, rig: 7, top: 9}},

     

       145
       145
       +
         {32, 15} => {4, %{bot: 8, lft: 8, rig: 9, top: 8}},

     

       146
       146
       +
         {89, 14} => {0, %{bot: 4, lft: 6, rig: 8, top: 8}},

     

       147
       147
       +
         {35, 30} => {3, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       148
       148
       +
         {37, 53} => {9, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       149
       149
       +
         {4, 5} => {4, %{bot: 7, lft: 4, rig: 7, top: 4}},

     

       150
       150
       +
         {8, 50} => {4, %{bot: 9, lft: 8, rig: 7, top: 6}},

     

       151
       151
       +
         {78, 98} => {6, %{bot: 6, lft: 9, rig: -1, top: 7}},

     

       152
       152
       +
         {95, 56} => {5, %{bot: 5, lft: 7, rig: 7, top: 9}},

     

       153
       153
       +
         {74, 12} => {1, %{bot: 6, lft: 7, rig: 9, top: 8}},

     

       154
       154
       +
         {11, 39} => {0, %{bot: 9, lft: 8, rig: 8, top: 7}},

     

       155
       155
       +
         {65, 43} => {6, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       156
       156
       +
         {22, 38} => {1, %{bot: 9, lft: 9, rig: 9, top: 8}},

     

       157
       157
       +
         {14, 86} => {5, %{bot: 8, lft: 9, rig: 5, top: 6}},

     

       158
       158
       +
         {20, 41} => {5, %{bot: 9, lft: 8, rig: 9, top: 9}},

     

       159
       159
       +
         {29, 25} => {3, %{bot: 9, lft: 9, rig: 9, top: 7}},

     

       160
       160
       +
         {86, 10} => {3, %{bot: 5, lft: 6, rig: 8, top: 8}},

     

       161
       161
       +
         {83, 36} => {5, %{bot: 8, lft: 7, rig: 9, top: 9}},

     

       162
       162
       +
         {29, 26} => {2, %{bot: 9, lft: 9, rig: 9, top: 8}},

     

       163
       163
       +
         {47, 27} => {3, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       164
       164
       +
         {4, 81} => {4, %{bot: 9, lft: 7, rig: 5, top: 4}},

     

       165
       165
       +
         {31, 42} => {5, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       166
       166
       +
         {9, 34} => {2, %{bot: 9, lft: 7, rig: 8, top: 7}},

     

       167
       167
       +
         {90, 0} => {4, %{bot: 4, lft: -1, rig: 8, top: 7}},

     

       168
       168
       +
         {67, 98} => {1, %{bot: 6, lft: 9, rig: -1, top: 7}},

     

       169
       169
       +
         {13, 85} => {0, %{bot: 9, lft: 8, rig: 6, top: 6}},

     

       170
       170
       +
         {63, 81} => {9, %{bot: 7, lft: 9, rig: 8, top: 9}},

     

       171
       171
       +
         {82, 60} => {6, %{bot: 8, lft: 9, rig: 9, top: 9}},

     

       172
       172
       +
         {47, 38} => {4, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       173
       173
       +
         {15, 92} => {2, %{bot: 7, lft: 9, rig: 6, top: 6}},

     

       174
       174
       +
         {58, 58} => {8, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       175
       175
       +
         {20, 3} => {6, %{bot: 7, lft: 3, rig: 9, top: 5}},

     

       176
       176
       +
         {61, 95} => {3, %{bot: 7, lft: 9, rig: 7, top: 7}},

     

       177
       177
       +
         {23, 67} => {9, %{bot: 9, lft: 9, rig: 9, top: 9}},

     

       178
       178
       +
         {78, 75} => {1, %{bot: 6, lft: 9, rig: 7, top: 9}},

     

       179
       179
       +
         {79, 17} => {6, %{bot: 6, lft: 7, rig: 9, top: 9}},

     

       180
       180
       +
         {75, 0} => {5, %{bot: 6, lft: -1, rig: 9, top: 7}},

     

       181
       181
       +
         {16, 73} => {4, %{bot: 9, lft: 9, rig: 7, top: 8}},

     

       182
       182
       +
         {76, 2} => {3, %{bot: 6, lft: 4, rig: 9, top: 7}},

     

       183
       183
       +
         {58, 84} => {9, %{bot: 8, lft: 9, rig: 6, ...}},

     

       184
       184
       +
         {58, 33} => {6, %{bot: 9, lft: 9, ...}},

     

       185
       185
       +
         {47, 44} => {5, %{bot: 9, ...}},

     

       186
       186
       +
         {54, 31} => {9, %{...}},

     

       187
       187
       +
         {13, ...} => {3, ...},

     

       188
       188
       +
         {...} => {...},

     

       189
       189
       +
         ...

     

       190
       190
       +
       }

     

       191
       191
       +
       ```

     

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       +
       

     

       193
       193
       +
       ```elixir

     

       194
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       +
       map

     

       195
       195
       +
       |> Enum.count(fn {_, {v, maxes}} ->

     

       196
       196
       +
         maxes

     

       197
       197
       +
         |> Map.values()

     

       198
       198
       +
         |> Enum.any?(&(v > &1))

     

       199
       199
       +
       end)

     

       200
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       +
       ```

     

       201
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       +
       

     

       202
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       +
       <!-- livebook:{"output":true} -->

     

       203
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       +
       

     

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       +
       ```

     

       205
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       +
       1538

     

       206
       206
       +
       ```

     

       207
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       +
       

     

       208
       208
       +
       ## Task 2

     

       209
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       +
       

     

       210
       210
       +
       ```elixir

     

       211
       211
       +
       defmodule Task2 do

     

       212
       212
       +
         def range(range, value) do

     

       213
       213
       +
           Map.new(range, &{&1, value})

     

       214
       214
       +
         end

     

       215
       215
       +
       end

     

       216
       216
       +
       ```

     

       217
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       +
       

     

       218
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       +
       <!-- livebook:{"output":true} -->

     

       219
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       +
       

     

       220
       220
       +
       ```

     

       221
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       +
       {:module, Task2, <<70, 79, 82, 49, 0, 0, 6, ...>>, {:range, 2}}

     

       222
       222
       +
       ```

     

       223
       223
       +
       

     

       224
       224
       +
       ```elixir

     

       225
       225
       +
       empty = Task2.range(0..9, 0)

     

       226
       226
       +
       

     

       227
       227
       +
       l_map =

     

       228
       228
       +
         Enum.flat_map(0..width, fn x ->

     

       229
       229
       +
           {list, _} =

     

       230
       230
       +
             Enum.map_reduce(0..height, empty, fn y, acc ->

     

       231
       231
       +
               # IO.inspect({{x, y}, acc})

     

       232
       232
       +
               v = raw_map[{x, y}]

     

       233
       233
       +
               dist = y - acc[v]

     

       234
       234
       +
               new_acc = Map.merge(acc, Task2.range(0..v, y))

     

       235
       235
       +
       

     

       236
       236
       +
               {{{x, y}, dist}, new_acc}

     

       237
       237
       +
             end)

     

       238
       238
       +
       

     

       239
       239
       +
           list

     

       240
       240
       +
         end)

     

       241
       241
       +
         |> Map.new()

     

       242
       242
       +
       

     

       243
       243
       +
       t_map =

     

       244
       244
       +
         Enum.flat_map(0..width, fn y ->

     

       245
       245
       +
           {list, _} =

     

       246
       246
       +
             Enum.map_reduce(0..height, empty, fn x, acc ->

     

       247
       247
       +
               v = raw_map[{x, y}]

     

       248
       248
       +
               dist = x - acc[v]

     

       249
       249
       +
               new_acc = Map.merge(acc, Task2.range(0..v, x))

     

       250
       250
       +
       

     

       251
       251
       +
               {{{x, y}, dist}, new_acc}

     

       252
       252
       +
             end)

     

       253
       253
       +
       

     

       254
       254
       +
           list

     

       255
       255
       +
         end)

     

       256
       256
       +
         |> Map.new()

     

       257
       257
       +
       

     

       258
       258
       +
       empty = Task2.range(0..9, width)

     

       259
       259
       +
       

     

       260
       260
       +
       r_map =

     

       261
       261
       +
         Enum.flat_map(height..0//-1, fn x ->

     

       262
       262
       +
           {list, _} =

     

       263
       263
       +
             Enum.map_reduce(width..0//-1, empty, fn y, acc ->

     

       264
       264
       +
               v = raw_map[{x, y}]

     

       265
       265
       +
               dist = acc[v] - y

     

       266
       266
       +
               new_acc = Map.merge(acc, Task2.range(0..v, y))

     

       267
       267
       +
       

     

       268
       268
       +
               {{{x, y}, dist}, new_acc}

     

       269
       269
       +
             end)

     

       270
       270
       +
       

     

       271
       271
       +
           list

     

       272
       272
       +
         end)

     

       273
       273
       +
         |> Map.new()

     

       274
       274
       +
       

     

       275
       275
       +
       b_map =

     

       276
       276
       +
         Enum.flat_map(width..0//-1, fn y ->

     

       277
       277
       +
           {list, _} =

     

       278
       278
       +
             Enum.map_reduce(height..0//-1, empty, fn x, acc ->

     

       279
       279
       +
               v = raw_map[{x, y}]

     

       280
       280
       +
               dist = acc[v] - x

     

       281
       281
       +
               new_acc = Map.merge(acc, Task2.range(0..v, x))

     

       282
       282
       +
       

     

       283
       283
       +
               {{{x, y}, dist}, new_acc}

     

       284
       284
       +
             end)

     

       285
       285
       +
       

     

       286
       286
       +
           list

     

       287
       287
       +
         end)

     

       288
       288
       +
         |> Map.new()

     

       289
       289
       +
       

     

       290
       290
       +
       merger = fn _, a, b -> a * b end

     

       291
       291
       +
       

     

       292
       292
       +
       l_map

     

       293
       293
       +
       |> Map.merge(t_map, merger)

     

       294
       294
       +
       |> Map.merge(r_map, merger)

     

       295
       295
       +
       |> Map.merge(b_map, merger)

     

       296
       296
       +
       |> Enum.max_by(&elem(&1, 1))

     

       297
       297
       +
       ```

     

       298
       298
       +
       

     

       299
       299
       +
       <!-- livebook:{"output":true} -->

     

       300
       300
       +
       

     

       301
       301
       +
       ```

     

       302
       302
       +
       {{9, 63}, 496125}

     

       303
       303
       +
       ```

     

       304
       304
       +
       

     

       305
       305
       +
       ```elixir

     

       306
       306
       +
       {l_map[{3, 2}], t_map[{3, 2}], b_map[{3, 2}], r_map[{3, 2}]}

     

       307
       307
       +
       ```

     

       308
       308
       +
       

     

       309
       309
       +
       <!-- livebook:{"output":true} -->

     

       310
       310
       +
       

     

       311
       311
       +
       ```

     

       312
       312
       +
       {2, 1, 1, 1}

     

       313
       313
       +
       ```

+203

2022/day09.livemd

···

       1
       1
       +
       <!-- livebook:{"persist_outputs":true} -->

     

       2
       2
       +
       

     

       3
       3
       +
       # Day 09

     

       4
       4
       +
       

     

       5
       5
       +
       ```elixir

     

       6
       6
       +
       Mix.install([

     

       7
       7
       +
         {:kino_aoc, git: "https://github.com/ljgago/kino_aoc"}

     

       8
       8
       +
       ])

     

       9
       9
       +
       ```

     

       10
       10
       +
       

     

       11
       11
       +
       <!-- livebook:{"output":true} -->

     

       12
       12
       +
       

     

       13
       13
       +
       ```

     

       14
       14
       +
       :ok

     

       15
       15
       +
       ```

     

       16
       16
       +
       

     

       17
       17
       +
       ## Setup

     

       18
       18
       +
       

     

       19
       19
       +
       <!-- livebook:{"attrs":{"day":"9","session_secret":"ADVENT_OF_CODE_SESSION","variable":"puzzle_input","year":"2022"},"kind":"Elixir.KinoAOC.HelperCell","livebook_object":"smart_cell"} -->

     

       20
       20
       +
       

     

       21
       21
       +
       ```elixir

     

       22
       22
       +
       {:ok, puzzle_input} =

     

       23
       23
       +
         KinoAOC.download_puzzle("2022", "9", System.fetch_env!("LB_ADVENT_OF_CODE_SESSION"))

     

       24
       24
       +
       ```

     

       25
       25
       +
       

     

       26
       26
       +
       <!-- livebook:{"output":true} -->

     

       27
       27
       +
       

     

       28
       28
       +
       ```

     

       29
       29
       +
       {:ok,

     

       30
       30
       +
        "L 1\nR 1\nL 1\nU 1\nR 2\nU 1\nD 2\nR 2\nU 1\nD 2\nU 2\nL 2\nD 1\nU 1\nD 2\nL 2\nD 1\nL 2\nD 2\nL 1\nU 2\nR 2\nL 1\nD 2\nL 2\nR 2\nD 2\nL 1\nU 1\nR 1\nU 1\nL 1\nD 1\nR 1\nU 2\nD 2\nR 1\nU 1\nR 1\nL 1\nU 1\nR 1\nD 1\nL 1\nU 1\nR 1\nD 1\nU 1\nD 1\nU 1\nR 2\nL 2\nD 2\nL 2\nR 1\nU 2\nL 2\nR 1\nU 1\nR 2\nD 2\nR 2\nL 2\nU 2\nR 2\nD 2\nR 1\nU 1\nL 2\nR 1\nU 1\nD 2\nU 2\nD 1\nR 2\nL 2\nD 2\nL 2\nR 2\nU 1\nR 2\nL 2\nD 2\nL 1\nD 1\nR 2\nL 1\nU 2\nR 1\nU 2\nD 1\nU 2\nD 1\nL 1\nR 2\nD 2\nR 2\nU 2\nR 1\nU 2\nR 2\nU 1\nR 1\nD 2\nU 2\nR 2\nU 1\nR 2\nD 2\nR 1\nL 1\nU 3\nL 2\nU 1\nL 2\nU 1\nD 1\nU 2\nD 1\nU 2\nR 2\nL 1\nU 3\nR 1\nU 1\nR 3\nL 3\nD 3\nL 2\nU 1\nD 3\nU 1\nR 1\nL 1\nR 2\nL 1\nR 3\nL 3\nD 1\nR 2\nL 3\nU 3\nD 1\nL 2\nU 2\nD 2\nL 2\nU 1\nR 1\nL 2\nR 3\nL 3\nD 3\nR 2\nD 3\nU 1\nL 3\nR 1\nU 2\nL 1\nD 3\nL 1\nU 1\nD 3\nL 3\nU 2\nD 1\nU 2\nL 3\nR 1\nU 2\nD 2\nR 3\nD 3\nU 2\nD 3\nL 3\nR 3\nL 1\nU 3\nL 1\nD 1\nL 2\nD 2\nR 1\nL 3\nR 2\nL 3\nR 3\nL 1\nD 1\nU 3\nL 2\nR 2\nL 2\nD 3\nU 3\nL 3\nU 3\nD 1\nU 2\nR 2\nU 1\nD 3\nL 3\nR 1\nL 3\nU 3\nD 1\nL 3\nD 2\nR 1\nU 1\nR 1\nD 2\nL 2\nU 1\nL 2\nR 2\nL 2\nD 3\nU 3\nD 4\nL 3\nD 4\nR 3\nL 2\nU 3\nR 3\nU 1\nR 4\nU 2\nD 1\nR 3\nL 1\nR 1\nD 3\nR 2\nD 1\nR 2\nL 2\nU 2\nD 1\nR 1\nU 2\nR 3\nL 2\nD 1\nU 3\nR 2\nD 4\nL 3\nU 1\nR 1\nD 2\nU 1\nR 3\nL 4\nD 2\nL 1\nU 3\nL 2\nU 3\nR 1\nD 1\nL 2\nR 4\nD 4\nU 1\nR 3\nU 3\nR 1\nU 3\nL 2\nU 3\nL 2\nD 4\nU 1\nR 1\nL 2\nR 2\nD 2\nL 2\nD 2\nU 4\nD 4\nL 2\nU 2\nD 3\nL 4\nU 4\nD 4\nR 1\nD 4\nR 1\nD 1\nL 1\nR 1\nL 1\nD 2\nL 4\nD 2\nR 3\nL 1\nD 2\nU 3\nL 2\nU 3\nR 4\nD 4\nU 1\nL 1\nU 4\nL 4\nU 3\nD 2\nR 3\nL 1\nD 3\nU 3\nR 1\nL 3\nU 1\nD 1\nR 1\nU 3\nR 2\nL 1\nD 1\nL 3\nU 1\nD 1\nL 2\nR 3\nU 4\nL 5\nD 5\nR 5\nD 3\nU 3\nD 1\nL 5\nR 2\nU 1\nL 2\nD 1\nL 1\nD 4\nR 1\nU 1\nL 1\nU 1\nD 3\nL 4\nD 1\nU 5\nL 1\nR 5\nL 2\nR 4\nD 5\nU 2\nD 3\nU 4\nL 1\nR 2\nU 4\nL 4\nD 3\nR 1\nU 1\nR 3\nD 3\nU 5\nL 3\nD 3\nU 5\nR 4\nL 1\nD 4\nU 1\nL 1\nR 4\nD 5\nL 5\nD 3\nR 5\nU 3\nR 2\nD 2\nU 2\nD 5\nR 5\nD 5\nR 2\nD 5\nU 2\nD 2\nR 1\nL 5\nD 2\nU 2\nR 5\nU 1\nD 5\nU 5\nL 2\nD 5\nL 1\nR 4\nU 4\nD 1\nL 5\nU 4\nL 1\nR 3\nL 3\nR 3\nL 3\nD 3\nR 4\nU 5\nL 2\nD 3\nU 2\nL 1\nR 5\nU 1\nL 3\nU 4\nL 4\nD 4\nR 1\nD 4\nR 5\nD 5\nU 5\nR 5\nL 3\nD 3\nU 2\nR 5\nU 5\nR 2\nD 5\nR 1\nU 2\nD 5\nL 3\nR 5\nU 5\nR 4\nD 6\nL 4\nU 4\nL 6\nR 2\nL 4\nU 5\nL 1\nU 6\nD 4\nR 3\nU 2\nR 1\nD 5\nL 4\nU 2\nR 6\nU 1\nL 2\nD 6\nU 1\nR 2\nL 3\nR 2\nL 5\nU 1\nR 3\nD 3\nL 4\nR 5\nU 1\nD 3\nR 6\nD 5\nR 4\nD 3\nU 2\nD 4\nR 5\nU 4\nR 2\nL 2\nU 5\nD 5\nU 6\nD 4\nU 5\nL 5\nR 1\nD 3\nR 3\nL 3\nD 3\nL 3\nU 6\nR 5\nD 6\nU 5\nL 1\nR 4\nL 1\nU 4\nL 5\nD 5\nU 4\nD 3\nR 3\nL 4\nR 4\nU 6\nL 5\nD 2\nU 3\nR 4\nU 5\nL 5\nD 6\nR 5\nD 5\nL 3\nU 6\nL 3\nU 5\nD 2\nU 4\nR 4\nU 3\nD 1\nR 2\nL 6\nR 2\nL 3\nU 5\nL 1\nR 4\nD 2\nU 5\nD 2\nR 4\nU 6\nR 6\nL 6\nU 6\nL 4\nR 5\nD 3\nU 1\nD 6\nL 1\nD 3\nL 4\nD 6\nU 3\nD 2\nL 2\nU 5\nD 2\nU 5\nD 6\nR 4\nD 1\nU 1\nD 5\nU 1\nL 7\nU 3\nR 3\nU 5\nD 2\nR 7\nD 6\nL 7\nR 6\nL 3\nR 3\nU 1\nL 4\nD 4\nL 6\nR 1\nU 4\nL 3\nR 3\nD 3\nL 2\nD 7\nU 7\nD 7\nR 2\nL 6\nD 2\nR 6\nD 6\nU 5\nL 4\nU 3\nD 6\nU 3\nD 1\nL 7\nU 7\nL 4\nR 3\nD 6\nU 2\nL 6\nD 3\nU 7\nD 2\nR 7\nD 4\nL 4\nR 4\nU 2\nD 3\nU 2\nL 4\nR 4\nL 4\nD 6\nR 4\nU 1\nR 7\nD 7\nU 7\nR 6\nD 4\nU 2\nD 4\nL 5\nU 4\nD 6\nR 4\nU 2\nR 1\nU 4\nD 5\nR 1\nD 7\nR 4\nU 1\nD 4\nU 6\nL 6\nR 1\nD 1\nR 1\nD 6\nR 6\nD 3\nU 1\nD 5\nR 4\nL 1\nD 6\nR 6\nL 8\nU 1\nD 7\nR 4\nL 2\nR 6\nU 7\nL 2\nD 5\nR 6\nD 3\nL 4\nR 5\nU 7\nL 3\nU 8\nL 1\nU 6\nL 8\nR 7\nD 2\nU 3\nR 4\nL 8\nD 4\nL 1\nU 1\nD 7\nU 8\nR 7\nD 2\nL 5\nU 6\nD 7\nR 4\nL 1\nR 3\nU 1\nR 2\nU 1\nD 7\nR 6\nU 7\nD 6\nL 2\nD 8\nU 4\nR 8\nL 5\nD 6\nL 7\nU 7\nR 8\nL 5\nD 5\nR 4\nL 5\nU 8\nD 4\nU 6\nD 2\nU 5\nR 7\nL 8\nU 7\nR 3\nL 8\nR 6\nD 4\nR 2\nD 6\nR 5\nD 2\nU 6\nL 4\nU 8\nR 3\nU 1\nL 6\nR 1\nL 3\nR 1\nU 3\nL 8\nD 5\nU 6\nL 8\nD 6\nR 2\nU 6\nR 4\nL 8\nD 1\nR 6\nD 8\nU 6\nD 6\nL 3\nU 4\nD 2\nL 2\nD 7\nL 5\nU 3\nR 8\nD 6\nR 5\nL 8\nU 5\nL 9\nR 7\nD 5\nR 2\nU 5\nL 3\nD 9\nR 4\nU 1\nL 3\nR 5\nL 7\nR 8\nD 1\nU 4\nL 4\nR 3\nU 8\nL 8\nD 8\nU 9\nR 6\nU 3\nR 2\nU 8\nD 9\nR 3\nL 2\nU 9\nR 9\nL 8\nD 2\nR 1\nL 8\nU 7\nR 3\nL 1\nR 9\nL 4\nR 2\nU 3\nD 8\nR 5\nU 9\nL 9\nR 1\nD 5\nR 5\nU 4\nL 9\nR 6\nD 5\nL 2\nR 6\nU 1\nD 5\nL 3\nR 1\nU 5\nR 4\nD 4\nU 8\nD 2\nU 6\nR 6\nU 5\nR 3\nU 5\nR 5\nL 8\nD 9\nL 7\nR 1\nU 7\nR 5\nU 6\nR 8\nU 2\nR 2\nU 8\nR 7\nD 3\nR 6\nL 8\nR 4\nL 8\nR 8\nU 8\nR 3\nL 3\nU 1\nL 9\nD 9\nR 9\nU 4\nR 1\nL 3\nD 4\nU 5\nR 7\nD 6\nL 9\nU 7\nL 4\nR 8\nU 8\nD 4\nL 5\nD 9\nU 2\nD 9\nR 4\nD 8\nR 8\nD 8\nU 9\nL 6\nR 6\nL 2\nU 9\nL 4\nU 10\nL 1\nR 10\nD 3\nU 6\nR 5\nD 3\nR 4\nL 4\nU 7\nD 9\nR 2\nD 10\nU 9\nL 7\nD 4\nR 2\nL 10\nD 5\nR 5\nU 9\nR 4\nL 7\nR 5\nD 3\nR 6\nD 8\nR 6\nD 10\nR 7\nU 4\nD 5\nU 6\nL 3\nD 3\nU 10\nR 10\nU 10\nD 9\nR 6\nD 2\nR 9\nD 8\nR 7\nU 10\nR 4\nU 6\nR 7\nU 2\nR 5\nU 6\nL 4\nU 8\nL 6\nD 8\nR 2\nU 2\nL 4\nU 4\nR 5\nU 10\nD 8\nU 7\nR 5\nD 3\nL 2\nR 9\nU 10\nL 1\nU 5\nL 1\nD 3\nL 9\nR 9\nU 2\nD 3\nU 8\nR 10\nL 2\nU 9\nD 4\nU 4\nD 10\nL 4\nD 3\nR 3\nL 2\nU 8\nL 4\nD 6\nR 2\nL 3\nD 6\nL 4\nD 5\nL 7\nU 9\nL 3\nD 4\nR 6\nL 10\nU 5\nL 3\nR 3\nD 6\nU 1\nL 3\nR 5\nD 8\nR 11\nU 2\nL 11\nR 7\nU 8\nR 4\nD 4\nU 6\nD 4\nU 9\nD 5\nR 9\nD 9\n" <> ...}

     

       31
       31
       +
       ```

     

       32
       32
       +
       

     

       33
       33
       +
       ```elixir

     

       34
       34
       +
       moves =

     

       35
       35
       +
         puzzle_input

     

       36
       36
       +
         |> String.split("\n", trim: true)

     

       37
       37
       +
         |> Enum.map(fn line ->

     

       38
       38
       +
           [dir, steps] = String.split(line)

     

       39
       39
       +
       

     

       40
       40
       +
           {dir, String.to_integer(steps)}

     

       41
       41
       +
         end)

     

       42
       42
       +
       ```

     

       43
       43
       +
       

     

       44
       44
       +
       <!-- livebook:{"output":true} -->

     

       45
       45
       +
       

     

       46
       46
       +
       ```

     

       47
       47
       +
       [

     

       48
       48
       +
         {"L", 1},

     

       49
       49
       +
         {"R", 1},

     

       50
       50
       +
         {"L", 1},

     

       51
       51
       +
         {"U", 1},

     

       52
       52
       +
         {"R", 2},

     

       53
       53
       +
         {"U", 1},

     

       54
       54
       +
         {"D", 2},

     

       55
       55
       +
         {"R", 2},

     

       56
       56
       +
         {"U", 1},

     

       57
       57
       +
         {"D", 2},

     

       58
       58
       +
         {"U", 2},

     

       59
       59
       +
         {"L", 2},

     

       60
       60
       +
         {"D", 1},

     

       61
       61
       +
         {"U", 1},

     

       62
       62
       +
         {"D", 2},

     

       63
       63
       +
         {"L", 2},

     

       64
       64
       +
         {"D", 1},

     

       65
       65
       +
         {"L", 2},

     

       66
       66
       +
         {"D", 2},

     

       67
       67
       +
         {"L", 1},

     

       68
       68
       +
         {"U", 2},

     

       69
       69
       +
         {"R", 2},

     

       70
       70
       +
         {"L", 1},

     

       71
       71
       +
         {"D", 2},

     

       72
       72
       +
         {"L", 2},

     

       73
       73
       +
         {"R", 2},

     

       74
       74
       +
         {"D", 2},

     

       75
       75
       +
         {"L", 1},

     

       76
       76
       +
         {"U", 1},

     

       77
       77
       +
         {"R", 1},

     

       78
       78
       +
         {"U", 1},

     

       79
       79
       +
         {"L", 1},

     

       80
       80
       +
         {"D", 1},

     

       81
       81
       +
         {"R", 1},

     

       82
       82
       +
         {"U", 2},

     

       83
       83
       +
         {"D", 2},

     

       84
       84
       +
         {"R", 1},

     

       85
       85
       +
         {"U", 1},

     

       86
       86
       +
         {"R", 1},

     

       87
       87
       +
         {"L", 1},

     

       88
       88
       +
         {"U", 1},

     

       89
       89
       +
         {"R", 1},

     

       90
       90
       +
         {"D", 1},

     

       91
       91
       +
         {"L", 1},

     

       92
       92
       +
         {"U", 1},

     

       93
       93
       +
         {"R", 1},

     

       94
       94
       +
         {"D", 1},

     

       95
       95
       +
         {"U", 1},

     

       96
       96
       +
         {"D", ...},

     

       97
       97
       +
         {...},

     

       98
       98
       +
         ...

     

       99
       99
       +
       ]

     

       100
       100
       +
       ```

     

       101
       101
       +
       

     

       102
       102
       +
       ```elixir

     

       103
       103
       +
       defmodule Rope do

     

       104
       104
       +
         @start %{x: 0, y: 0}

     

       105
       105
       +
       

     

       106
       106
       +
         defstruct segments: [%{x: 0, y: 0}, %{x: 0, y: 0}]

     

       107
       107
       +
       

     

       108
       108
       +
         def new(length),

     

       109
       109
       +
           do: %__MODULE__{segments: List.duplicate(@start, length + 1)}

     

       110
       110
       +
       

     

       111
       111
       +
         def last(%__MODULE__{segments: list}), do: List.last(list)

     

       112
       112
       +
       

     

       113
       113
       +
         def move(%__MODULE__{segments: [%{x: x, y: y} | tails]}, dir) do

     

       114
       114
       +
           head =

     

       115
       115
       +
             case dir do

     

       116
       116
       +
               "U" -> %{x: x + 1, y: y}

     

       117
       117
       +
               "D" -> %{x: x - 1, y: y}

     

       118
       118
       +
               "L" -> %{x: x, y: y + 1}

     

       119
       119
       +
               "R" -> %{x: x, y: y - 1}

     

       120
       120
       +
             end

     

       121
       121
       +
       

     

       122
       122
       +
           segments = move_tails([head | tails])

     

       123
       123
       +
       

     

       124
       124
       +
           %__MODULE__{segments: segments}

     

       125
       125
       +
         end

     

       126
       126
       +
       

     

       127
       127
       +
         defp move_tails([]), do: []

     

       128
       128
       +
         defp move_tails([head]), do: [head]

     

       129
       129
       +
       

     

       130
       130
       +
         # When nothing else moves, then stop

     

       131
       131
       +
         defp move_tails([head, tail | _] = rope)

     

       132
       132
       +
              when abs(head.x - tail.x) < 2 and abs(head.y - tail.y) < 2,

     

       133
       133
       +
              do: rope

     

       134
       134
       +
       

     

       135
       135
       +
         defp move_tails([head, tail | rest])

     

       136
       136
       +
              when abs(head.y - tail.y) < 2,

     

       137
       137
       +
              do: [head | move_tails([%{x: head.x - sgn(head.x - tail.x), y: head.y} | rest])]

     

       138
       138
       +
       

     

       139
       139
       +
         defp move_tails([head, tail | rest])

     

       140
       140
       +
              when abs(head.x - tail.x) < 2,

     

       141
       141
       +
              do: [head | move_tails([%{x: head.x, y: head.y - sgn(head.y - tail.y)} | rest])]

     

       142
       142
       +
       

     

       143
       143
       +
         defp move_tails([head, tail | rest]),

     

       144
       144
       +
           do: [

     

       145
       145
       +
             head

     

       146
       146
       +
             | move_tails([%{x: head.x - sgn(head.x - tail.x), y: head.y - sgn(head.y - tail.y)} | rest])

     

       147
       147
       +
           ]

     

       148
       148
       +
       

     

       149
       149
       +
         def sgn(0), do: 0

     

       150
       150
       +
         def sgn(n) when n < 0, do: -1

     

       151
       151
       +
         def sgn(_), do: 1

     

       152
       152
       +
       end

     

       153
       153
       +
       ```

     

       154
       154
       +
       

     

       155
       155
       +
       <!-- livebook:{"output":true} -->

     

       156
       156
       +
       

     

       157
       157
       +
       ```

     

       158
       158
       +
       {:module, Rope, <<70, 79, 82, 49, 0, 0, 21, ...>>, {:sgn, 1}}

     

       159
       159
       +
       ```

     

       160
       160
       +
       

     

       161
       161
       +
       ```elixir

     

       162
       162
       +
       rope = Rope.new(1)

     

       163
       163
       +
       

     

       164
       164
       +
       {_rope, tail_positions} =

     

       165
       165
       +
         moves

     

       166
       166
       +
         |> Enum.flat_map(fn {dir, steps} -> List.duplicate(dir, steps) end)

     

       167
       167
       +
         |> Enum.reduce({rope, MapSet.new([Rope.last(rope)])}, fn dir, {rope, acc} ->

     

       168
       168
       +
           new_rope = Rope.move(rope, dir)

     

       169
       169
       +
       

     

       170
       170
       +
           {new_rope, MapSet.put(acc, Rope.last(new_rope))}

     

       171
       171
       +
         end)

     

       172
       172
       +
       

     

       173
       173
       +
       MapSet.size(tail_positions)

     

       174
       174
       +
       ```

     

       175
       175
       +
       

     

       176
       176
       +
       <!-- livebook:{"output":true} -->

     

       177
       177
       +
       

     

       178
       178
       +
       ```

     

       179
       179
       +
       5960

     

       180
       180
       +
       ```

     

       181
       181
       +
       

     

       182
       182
       +
       ## Task 2

     

       183
       183
       +
       

     

       184
       184
       +
       ```elixir

     

       185
       185
       +
       rope = Rope.new(9)

     

       186
       186
       +
       

     

       187
       187
       +
       {_rope, tail_positions} =

     

       188
       188
       +
         moves

     

       189
       189
       +
         |> Enum.flat_map(fn {dir, steps} -> List.duplicate(dir, steps) end)

     

       190
       190
       +
         |> Enum.reduce({rope, MapSet.new([Rope.last(rope)])}, fn dir, {rope, acc} ->

     

       191
       191
       +
           new_rope = Rope.move(rope, dir)

     

       192
       192
       +
       

     

       193
       193
       +
           {new_rope, MapSet.put(acc, Rope.last(new_rope))}

     

       194
       194
       +
         end)

     

       195
       195
       +
       

     

       196
       196
       +
       MapSet.size(tail_positions)

     

       197
       197
       +
       ```

     

       198
       198
       +
       

     

       199
       199
       +
       <!-- livebook:{"output":true} -->

     

       200
       200
       +
       

     

       201
       201
       +
       ```

     

       202
       202
       +
       2327

     

       203
       203
       +
       ```