this repo has no description
2024 day 09
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2024/day09.livemd
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2024/day09.livemd
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<!-- livebook:{"persist_outputs":true} -->
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# Day 09
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```elixir
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Mix.install([:kino_aoc])
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```
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## Section
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<!-- livebook:{"attrs":"eyJhc3NpZ25fdG8iOiJwdXp6bGVfaW5wdXQiLCJkYXkiOiI5Iiwic2Vzc2lvbl9zZWNyZXQiOiJBRFZFTlRfT0ZfQ09ERV9TRVNTSU9OIiwieWVhciI6IjIwMjQifQ","chunks":null,"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("2024", "9", 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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"6920945132536042828994482345396169724991532616269072173941615129441070989533549353544192338215647480107561245832285861135469128938656230362333818111433746344751894125805448321674418337459440436476402523264257512621383849394968854739721644705231266361534476141022646838663844981685665728936624151235476791584929822482292987334479824016888196957024425673938289753698621244157130975989396226731549454298144391686468562820376390235135108330238590316674261440783039581594584646247629719986582560203598244312596985279832984526808559405915881067383593502384107494586724976925694948216635952475703445963854271259175649271576378184603074946598276445248640841860479933368524996925945274749282264063148922416399632485376097486952663787643633316356949469798134153950341455917737349115548390535536536397237654519556679716185652595572754749672866345553911576628161614338861880658781637382837898686889463249126116447176285128303560134154431099612772162289797131303641655015516771696046959228585241299646581370538088916416989047515564526116366867367181678616439431284930379889626059473847818663132232979123503952455854489755245141781899866948543116887346827534697893607177987563154596774691267167851154138330695352108499217988406372425774968626985943665687196181233111972699532427257992757984672882888037943925818450345177398760216079692074854569485530377584183586279552981343712063437565138087959796501957177177884278405560475435141829787014884681355059571489723985901554488154898784759668954752934048679146776060562786272011429026535298115262548593878183498916571398351436431313482968486771572527901996664899792152552410493090499727835643526428881322227999149881884793853729989624533029587010105028429614225841889414576176753414877452414680577843459538128911939238704598815126186492327558383740971333501769852667796188543180462490517062819496532859194781303437743159526136553370517461484469733677187178992265612439155938358015666261906673153823768535183244601645561579916316476813124539675061263411515873626197742860301068615568696174716481151333516718804424987323957615961444822618946925923196806747458558553262735686467327309580525855605085698452928593956820699112556481136173708346321771719645737818963669665547522134505223646796667286359173528172301211931188731691358636677670346032949579894428251583802532214067603254278658698940647270167640764638397570409829821264846762426836572463386475815673329747876757249732659277388030843590439617143487927833367461978526979212861844382550791390358527895937281110537852835869713059958217969899704145215985377666628719451233132412294358444746793946343553683032671225858498134340537229859741987180829468238642605723478228646886791227546199853372232566387139711011753555879744151132642224546223435667375781861424845134566438891443785750344893853718679532879854483395621276216275644617996376282773738211864275304297979547422875934634992111232368475557713129934172577624852042405732858060209959806520925730394293739081861693532946112557827992852621975727432957291082907728921029905725787812513023871891551681262814572424452648875694586632916946898788794936727799526748807158546930659285568029733948646265541485187570661411984840326374573377475525442055851882711851241546246736884066686885724058588220382743451817154627144869212944944985727560911326298754699513901913775411631051155448259136813383243697125190592983671813131786588158152523929049549018258627964330945831994544156999373027523966329015316477207024639470312244244043635392684240435826402148884612989874566739774998162494686244143442812672951249922585423333957811202767768597518787769627151336335561386093158376767595684951873065594471827052965041948820794865486179401375326111497235854418829486872664452298163169179763609277741983868518845423468770227926607088302941698125295594475259881783566721809397453893791727816025381929613950311537338366491240658016437269618697401059446097141870959520762921795565136242743648578086232855147488427619213536145259919693337741268680894834764319547389247696113145205712656834305853252319218569748862345539664553175240528621328137233671331496239591159242157540311894387168" <> ...}
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```
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```elixir
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#puzzle_input = "2333133121414131402"
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tags =
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Stream.from_index()
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|> Stream.intersperse(:gap)
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files =
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puzzle_input
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|> String.split("", trim: true)
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|> Enum.map(&String.to_integer/1)
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|> Enum.zip(tags)
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```
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<!-- livebook:{"output":true} -->
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```
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[
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{6, 0},
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{9, :gap},
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{2, 1},
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{0, :gap},
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{9, 2},
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{4, :gap},
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{5, 3},
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{1, :gap},
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{3, 4},
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{2, :gap},
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{5, 5},
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{3, :gap},
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{6, 6},
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{0, :gap},
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{4, 7},
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{2, :gap},
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{8, 8},
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{2, :gap},
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{8, 9},
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{9, :gap},
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{9, 10},
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{4, :gap},
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{4, 11},
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{8, :gap},
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{2, 12},
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{3, :gap},
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{4, 13},
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{5, :gap},
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{3, 14},
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{9, :gap},
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{6, 15},
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{1, :gap},
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{6, 16},
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{9, :gap},
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{7, 17},
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{2, :gap},
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{4, 18},
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{9, :gap},
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{9, 19},
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{1, :gap},
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{5, 20},
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{3, :gap},
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{2, 21},
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{6, :gap},
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{1, 22},
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{6, :gap},
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{2, 23},
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{6, :gap},
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{9, ...},
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{...},
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...
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]
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```
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```elixir
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defmodule Disk do
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def checksum(files) do
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files
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|> Enum.reduce({0, 0}, fn
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{gap, :gap}, {pos, sum} ->
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{pos + gap, sum}
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{len, idx}, {pos, sum} ->
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new_pos = pos + len
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score = Enum.sum(pos..(new_pos - 1)) * idx
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{new_pos, score + sum}
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end)
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|> elem(1)
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end
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def display(lst) do
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Enum.map(lst, fn
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{len, val} ->
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sym = if val == :gap, do: ".", else: to_string(val)
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List.duplicate(sym, len)
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end)
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|> IO.iodata_to_binary()
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end
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end
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```
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<!-- livebook:{"output":true} -->
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```
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{:module, Disk, <<70, 79, 82, 49, 0, 0, 11, ...>>, {:display, 1}}
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```
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## Part 1
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```elixir
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defmodule Compactor do
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def run(files) do
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occupied =
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Enum.reduce(files, 0, fn
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{_, :gap}, acc -> acc
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{len, _idx}, acc -> acc + len
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end)
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compact([], occupied, files, Enum.reverse(files))
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end
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defp compact(acc, 0, _, _), do: Enum.reverse(acc)
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defp compact(acc, left, [{0, :gap} | rest], rfiles),
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do: compact(acc, left, rest, rfiles)
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defp compact(acc, left, rest, [{_, :gap} | rfiles]),
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do: compact(acc, left, rest, rfiles)
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defp compact(acc, left, rest, [{0, _idx} | rfiles]) do
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compact(acc, left, rest, rfiles)
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end
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defp compact(acc, left, [{gap, :gap} | rest], [{len, idx} | rfiles]) do
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fill = min(gap, len)
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compact([{fill, idx} | acc], left - fill, [{gap - fill, :gap} | rest], [
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{len - fill, idx} | rfiles
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])
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end
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defp compact(acc, left, [{len, idx} = file | rest], rfiles) when is_integer(idx) do
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compact([file | acc], left - len, rest, rfiles)
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end
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end
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```
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<!-- livebook:{"output":true} -->
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```
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{:module, Compactor, <<70, 79, 82, 49, 0, 0, 11, ...>>, {:compact, 4}}
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```
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```elixir
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files
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|> Compactor.run()
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|> Disk.checksum()
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```
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<!-- livebook:{"output":true} -->
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```
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6332189866718
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```
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## Part 2
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```elixir
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defmodule Defrag do
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def run(files) do
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files
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|> Enum.reverse()
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|> Enum.reduce(files, fn
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{_, :gap}, acc -> acc
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file, acc -> do_run(acc, file, [])
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end)
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end
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defp do_run([], _, acc), do: Enum.reverse(acc)
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defp do_run([file | _] = list, file, acc), do: Enum.reverse(acc, list)
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defp do_run([{len, :gap} | rest], {len, idx}, acc),
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do: Enum.reverse(acc, [{len, idx} | rep(rest, {len, idx})])
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defp do_run([{gap, :gap} | rest], {len, idx}, acc) when len < gap,
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do: Enum.reverse(acc, [{len, idx}, {gap - len, :gap} | rep(rest, {len, idx})])
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defp do_run([hd | rest], file, acc), do: do_run(rest, file, [hd | acc])
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defp rep([{a, :gap}, file, {b, :gap} | rest], {len, _} = file),
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do: [{a + len + b, :gap} | rest]
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defp rep([{a, :gap}, file | rest], {len, _} = file), do: [{a + len, :gap} | rest]
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defp rep([file, {b, :gap} | rest], {len, _} = file), do: [{len + b, :gap} | rest]
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defp rep([file | rest], {len, _} = file), do: [{len, :gap} | rest]
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defp rep([hd | rest], file), do: [hd | rep(rest, file)]
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end
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```
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<!-- livebook:{"output":true} -->
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```
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{:module, Defrag, <<70, 79, 82, 49, 0, 0, 12, ...>>, {:rep, 2}}
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```
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```elixir
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files
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|> Defrag.run()
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|> Disk.checksum()
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```
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<!-- livebook:{"output":true} -->
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```
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6353648390778
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```
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<!-- livebook:{"offset":8665,"stamp":{"token":"XCP.-mRlAHFcVs4Mg2hQj8TCLWgOv8zjlatUnbxbgI43tZXllMXB8VfJTbRJrHTJ1k_FrGDhUdviUPyCSPNKqXk-ZOQ9PHWUPFkLaK5S4SMKa18Ny7WrQvSmaHuoE2R6vJhqrck","version":2}} -->