Day10

Setup

sample = """
[({(<(())[]>[[{[]{<()<>>
[(()[<>])]({[<{<<[]>>(
{([(<{}[<>[]}>{[]{[(<()>
(((({<>}<{<{<>}{[]{[]{}
[[<[([]))<([[{}[[()]]]
[{[{({}]{}}([{[{{{}}([]
{<[[]]>}<{[{[{[]{()[[[]
[<(<(<(<{}))><([]([]()
<{([([[(<>()){}]>(<<{{
<{([{{}}[<[[[<>{}]]]>[]]
"""

input = """
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  ((<{[<([<<{[<(()())([]())>)<<<{}{}>{[][]}>{<<>>(()[])}>}<(((()[])[{}<>])[<[]{}>{{}[]}])[[({}{})
  ({(<[([((<(<[(<>{}){()[]}]<[[]<>]<(){}]>><{(<>())[<>{}]}{(<>[])(<>{})}>)([(<(){}>[(){}]){{()[]}{<>{}}}][<<[]
  {{{[(([{{{[{[(()())[<>[]]]{([]{}){()<>}}}]{{{((){})[[][]]}[[{}{}]<[]()>]}(<(<>()){{}{}>>([{}()
  [<{{{[[(<[(([<{}[]>{()()}][[<>{}]]))]([<<{{}[]}>>([(<>[])<(){}>][[{}{}](()())])]{[{[<><>]}((<>{})[
  {<[<[[<<(<<<<(<>[])(<>[])>{([]())}>[{{[]()}}<({}())[<>()]>]>{[((<>{})[[]<>])([()<>]{<>()})](((<>()
  ([({({[{(([<[<[]>]>]<<({[]()}<[]<>>)[[()[]]{[]{}}]>>))((<<{<<><>>}{(<>{})<[]()>}>([[<>{}]<<>{}>
  {(<([{{{{(((({{}[]}))){[(({}<>))({<><>}<[][]])][<<[]{}>[{}{}]>{<[]>{[]{}}}]})({[{([]<>)([]<>)}
  {([{{{(([<[[[<(){}>{()[]}][([]<>)<[]{}>]]<{(<>())[[]()]}[{(){}}[()<>]]>]([({[]{}}{()[])){{<>()}{()[]}}])>[<[
  [([{<{(<({<{[[<>{}][<>[]]]<{{}<>}<{}{}>>}[({()[]])[[<>()]({}<>)]]>{<([{}<>]<[]<>>)[{[]()}{{}[]}]>[[{[][]
  {{<(<{(<[<(((<[]<>><{}[]>))({(<>{}){[][]}}([[]()]({}<>))>)>[((((()<>)<<>[]>){(<>{}){<>{}}})(<({}(
  {{[{<{<([{[<{[{}{}]{(){}}}{{[]<>}<()[]>}>]<[({[][]}<{}<>>)(<{}{}><[]()>)]<[{<>{}}(()())]([[]{}]<[]<>>)>>>[{[{
  <(([<<{{<(([(({}{})[[]{}])[<{}>(<>{})]]<([{}{}]{()[]})>))({(<(()<>)<<><>>>(([]<>)))}<<<[()
  <<<(({{([{({({()()}<<>[]>)<{()[]}[<>()>>}){[<[<>{}][<><>]>[{()[]}[<><>]]]<<[<>[]]{<>()}>>}}[(<[[(){}](()
  <<[[{{([(([([[<>{}][(){}]])]{({{()}(<>{})}{{{}<>}{<><>}})(([<><>])({{}[]}<<><>>))})([{({()<>}<[][]>)}]))
  [(<<<<<{[<({[{{}[]}<()<>>]<[{}[]][[]<>]>})>[<<{(()())({}<>)}{({}())(<>[]]}><<<{}<>>([]<>)><[
  <<({({{([(<([[{}()]<[]{}>]<<<>()>>)><{(<{}<>><{}()>)<{(){}}[<>]>}{([[]{}][[]<>])<({}()){{}[
  {<{([[[[[{<<[[{}{}]([]<>)]{{{}()}[<><>]}><[<()()>[{}{}]](((){})<()>>>>}]<{({{([]()){{}<>}}<{<>{}}({}{}
  {[{[[<[((<(<<{<>}{()[]}>><{<<>[]>[()[]]}{{()()}[()[]]}>)(({[[]](<>[])}{({}())<{}()>})([[{}[]]<[]()>][{
  [{[(({[{{([[[<()()>{{}{}}]{([]<>){<><>}}]](<<<(){}>(()())>{[[]]{<>{}}>>))<[<((<>{}){(){}}){[{}<>]}>([[<><
  <{<(<([(<[({<<[]()>[[]{}]>(<{}<>>)}(<[{}[]][{}[]]>{<{}[]>[(){}]}))[<(<[]<>>{{}<>}]([[][]]<()<>>)>{({{}<>}[<>[
  {({({{<({[{[{<<>()>[[]{}]}](([{}<>]{()()})[([]()){[]()}})}[[((()())[()<>])(<<>{}><{}>)]]]<([{([]
  (<[([{({<([<(([]<>)<()[]>){{<>{}}[()()]}>])(([({[]()}<{}{}>)][<{{}[]}({})>[[<><>][<><>]]])<[({()[]}[[]{
  {{{<{{[[{[[<({[]()}{()[]})<[<>()][()()]>>(({{}{}}))][({[(){}](()[]]}){{<<>()>({})}{<{}[]>[{}<>]}}]]{[<
  {<([((<{<<<{(({}{})<<>[]>)(((){}){[]})}{({[]<>}[[]{}])<[{}[]][()()]>}}[{([<>()][<>{}]){(<>
  {([([(({[<[[[(())(<>[])]{[()()][<>]}]]>([{[(<><>)(<>())]<(()<>)[<><>]>}({{<>{}}({})}([{}][
  ([[[({[{{<{{{[{}()]{(){}}}[{()}({}[])]}[{[[]<>>(()[])}<{[][]}{[]}>]}>}}]}{[<[[[[(({}{}){{}[]}
  <[{<([<({((([[<>{}]([]())]<[()[]]<()<>>>){<<{}{}>[<><>]>[((){}){{}<>}]}))}({[({[()())(<>[])}{({}())}){([()[]
  {([[{[<<[[<{([<>()][{}{}])<([]{})(()[])>}{{{()()}{[][]}}<[[]{}]<<>{}>>}>(({<()()>({}())}[{<>[]}({}<>)])([[<
  ({[<{{[<{{(((([]<>){<>()})([()<>]([]{})))){{<{()()}[{}<>]>}({<{}[]>}{([]<>)<{}[]>})}}<<([{{}()}[{}[]]]<{(
  <({{([{[({<([({}())[()[]]]{([]{})})(([[]{}]{{}[]})([{}()><()<>>))>(<(({}{})<{}{}>)[{<><>}{[]
  [{[{<{([[[<[[{[][]}(<>{})]{{[]<>}[{}{}]}]><{({{}()}<[]()})}>]{{(<[[][]]{[]()}>{(()())(<>[])})(
  (<{(<[[<{[[<<([]<>)<{}{}>>({{}[]}({}()))>]({([[]<>]([]())){[<>{}]<{}()>}}[{({}())[(){}]}(({}{})[[]]
  <[<<([{[{<{{<[[][]]<<>[]>>({<>{}}[<><>])}([[{}<>]<()()>][<[][]>(()[])])}[({[()()][[]()]}[{{}()}<[]<>>])]>{<
  <(([[{(([[([[{{}()}{[]}]]<((<><>}({}[]))((()())[()[]])>)[{{<[]<>>((){})}}<(<(){}>{{}[]})({()}{{}<>})>]]<[(<{
  [{<(((<(<({(({{}()}{<><>})[{[][]}{(){}}])({{[]{}}[<>{}]>)})>((([<(<><>){{}<>}><[<>{}]>]([[<>[]][{}{}
  [<{{({([({({{{()<>}([][])>}((({}<>)(()[]))<(<>()){{}<>}>)){[([()()](<>[]))]{({[]}[[]{}])([[]<>
  {({[<{(<<([[[<{}{}>[{}{}]](<<>>(()))]{[([]<>)<{}{}>]<[<><>]>}]<[[{{}<>}<<>{}>][([]<>)<(){}
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  [<{<{<[{{[([(([]<>))[{<>()}<{}{}>]]{[<<>{}>[(){}]){<[][]>[<><>]}})](([<([]{})[{}()]>(({}())(<>{}))]
  [<[<{(<(([{<{([]{}){[][]}}><{[{}[]]([]<>)}[[()[]]<()()>]>}][{(<[(){}]{()<>}><<[]()>[[]()]>){[[<>[]](()[])
  <(<<<([[<([[({[]<>}<[]()>){{<>[]}[{}{}]}]([[[][]]<[]()>])]<{{(<><>){<>[]}}}{(<[][])(()[]))[([]{})[[
  (([{<{{([<<{({[]{}}[()[]])[<()()><()[]>]}[(<()>[()()])[[<>[]]]]>>{{{{<[]()>[()<>]}}{{<()[]>[()[]]}<[[][]]
  (<<[([[{{({<[([][])<{}()]][<()()>(()())]>})}<([[{(()<>)<[]()>}((()[])[<>{}])]]([<{(){}}({}<>)>][<
  [<<((<[<<{(((({}()))({<>{}}([]<>))){{<()<>><{}[]>}{(()())}}){({([]<>)<<>{}>})}}<{{<[()][<><>]>{{[]
  <{[<[((([{<{{{<>[]}[[]()]}([<><>])}>((<<<>()>({}<>)><[{}[]]<()[]>>)[{{[][]}{()<>}}[{()<>}(()[])]])}(([<{{
  {<{<[(({([<[<[[][])([]{})>[{(){}}[[]<>]]][(<{}<>>{()<>}){[<><>]{{}[]}}]>([[<[][]>{[]<>}]({[][]}(()()))]{
  (<{{{[{<{(<[({{}[]})]><<{(()<>)[{}{}]}{<()()>}>>)[[(({()<>}(<>{})))([<(){}>(()<>)]{((){})([][])})]
  <<[(<([<(({[{({}{})}<{()<>}{<>{}}>][([[]()](()<>))]}[[({{}()}<[]{}>)[<[]()>[()()]]]((<{}{}
  <<{[{[<{{{([<<<>{}>{()[]}>({{}[]}<<>{}>)][[<()[]>[{}[]]]({()<>}(()()))])[<<<<>()>{[]{}}>><{{[]{}}<()<>>}(<<>[
  [{{<({[([({{{(()())[<><>]}{[()()][(){}]}}}{[([<>[]])[{[]()}((){})]]([<[]{}>(()<>)]{[<>]})})(<
  <<<{{(({<{<[<<<>{}>>(<<>[]>{()()})]<([()<>])>>[(<({}[]){{}[]}>{[{}{}][[]()]})[<[<>[]]<()[]>>(<
  [([<<<(<[[[[[([]{}){{}()}}<<[]()>{[]}>][([<>[]]({}))[(()<>){()()}]]]]]>{[([[<([]())<{}<>>>({<>()}
  [([{{[[(({[<{[{}[]]{[][]]}<{<>()}[<>[]]>>(<{<>()}<[]()>>)]}))<<<<<{{()[]}{{}[]}}[<<>{}>]><{[{}<>]{(
  [{{{<((([{([{[[]()][<>()]}([[]()]{{}()})]{([{}{}](<>{}))({()<>}(<>{}))})<[({(){}}[()<>])}>}(
  {<<{{({[[[[[{[()]({})}<[<><>]{{}}}][[{()<>}({}{})][<<>[]>{<><>}]]]({<(<>)<<><>>>({<>()}<<>
  <[[[[({([[{<[{{}()}]{(()<>)<[]()>}>{[{<>{}}(()[])][{()[]}<()()>]}}]]<{[(({<>{}}{<>()})<[[]()]<<>{}>>)<((()[])
  ({{{<{[({[[[<{()<>}<<>[]>>{[[]<>][<>()]}]([(()<>)[[]()]]({{}[]}(()[]))]]][{{{<<>>({}<>)}<<<>{}
  [{[((<{<([[{<<()[]>[[][]]>}<{({})}[<{}[]>[[][]}]>]]<<{(([]<>)[[]()])}<{<{}()>{[]}}{[()[]]({})}>>
  [{([[{[({<[<(<<>{}>({}[]))([{}<>]{(){}})}({<[][]>}{[()()]<{}[]>})]<<[<(){}>[<>{}]][<<>{}>({}{
  [<([{<<[((([<[<>()]({}())><([]{})<{}[]>>]))[{[[[[]()]]]}{{[{[]()}([][])]{<[][]>{{}()}}}}])<(({{(<>()){
  {{[[<{{(({{{(<{}<>>{()[]})[<[]()>]}[{<[]{}>[()[]]}]}<[{[[]<>][[][]]}<<(){}>((){})>][([()<>]<<>>)<
  <<{[(([{<((({([][]){[]<>}}{({}())}))({[<<>{}><<>>]}{<[<>{}](()())><<{}[]>{()<>}>)))({[<(<>[
  <[<((<<[[<[((([]<>)<(){}>)[<(){}>])({<{}{}>{<><>}}<(()())<[]{}>>)]{{({(){}}(()[]))}<({<><>}({}()))>}
  [<{(<([{[({[{({}{})<{}()>}[{[]<>}({}<>)]]})[<[([{}[]][()[]])((<>()){{}<>})][[[(){}][[][]]][<
  <(({([[(<[[{(<<><>><{}()>)<(()()){()[]}>}({[()<>][{}[]]}([<>{}]<<><>>)}]]{{[<[<>[]]>({<><>}([]{}))][(([][])<
  {[[[[<<[{(({{{[]()}[{}[]]}}{[[()()][{}{}]]}){[{{{}()}}[[[][]]<()()>]]}){[{((()<>)[{}<>]){<<>()>[()()]}}(([{}<
  [[<<<{<({[<([[()<>]]({()<>})){[{{}[]}]}>][({[<()<>>({}[])]}((<<><>>[<>])[({}())<{}{}>]))]})>}>[{{(({{[
  {{[[{{(([[[[({[]()}<{}()>)<(()[])<<>[]>>]]<(<{[][]}<{}()>>(({})[[][]]))>]<<{({()[]}[(){}]]({
  ({{((<([<({<(<[]<>><<>[]>){[{}<>]}>(<[{}{}]>)}[<{{<>{}}{[]()}}[<<><>>[[][]]]>[[<()()><(){}>]{<
  [[[(({{<(<{<[{()[]}]({<>{}})>[<<<>()>{{}{}}>{({}<>)<<>()>}]}<({{()()}}<(()()){<><>}>){<((){})(<>()
  {<{{(<{{<[[({<<>>}<[(){}]({}())>)[<{()<>}[{}()]>[({}[])<()()>]]]]{<[({<>{}}{[][]})]{[(<>{})({}())]}
  [<[<{<<({[[(((<>())[{}<>]))<(({}[])(()[])){{{}{}}[[]<>]}>]<[(<{}{}]{{}{}})<(()<>)>][[{<>{}}<[
  [({<(<[([<({([<>()]{[][]}>{<<>[]>[[]()]}}[{<()<>>([]<>)}])<<<[[]()](())>><[<<>[]>{{}()}]{<()
  {{[{(<<{[{({[<[]()>{{}<>}]([()<>]{{}[]})}<<<[]()>[[]<>]><[<>{}][()()]>>)}<{<[{[]()}{<>{}}]>{({[][]}<[]
  [[{[<<<[{[[<({<>()}((){})){{<>[]}<(){}>}>[<(()<>)({}<>)>{<[]()>(<>)}]]]{<<{[<>[]]>>(<<{}()>(<>())>(
  {({{[([<{{{<((<><>)<()()>][<{}[]>{<>[]}]><({<>()}(()<>))({{}[]}<()[]>)>}([({{}[]})({{}()}[<>[]])])}
  {<[[({{((<[{[{<>()}(<>())]<({}[])<<>{}>>}([(()())<<>[]>]((<>[]){{}{}}))]{({<()()>(()<>)}[{[][]}([]())])<<[()
  ([{((({<<<{<{{<><>}(()<>)}>}>)[{{[[[[][]]]][<(<>{}){[]}>([{}()][[][]])]}<{([()()][<>()])(<[]()>
  <(((<(({<<[{<(()())>[[[][]]<[]{}>]}[{{<>()}(<><>)}(({}())({}()))]]>((<({{}[]}(<>())){({}[])
  <<{[(<([<(<{{[<>{}]}(<<>()>({}{}))}><({<<>()>(<><>)}<<[][]>[[]()]>)(([<>()){{}()})<[[][]]{<>{}
  <<[[([{{{{[<{[(){}]<[]()>}>[[([])<[]<>>>[({}{})([][])]]]}<<({<()[]><{}<>>}<{()<>}(<><>)>)>(([
  {[[[{{[{{((<{[{}[]](()[])}<(<>{})(<><>)>>){(<<<>{}>>)(([()[]]<[]{}})[({}[])(()())])})}}]}{[{{({({([]
  ([{[{((([[{{([[][]][{}[]])[{[]<>}<<>[]>]}}]][<[{[(<>{})[[]<>]][{[]<>}[(){}]]}]{<[[{}[]]{{}[]}]><(({}
  {(<(<{<<([<<<[{}{}]<{}{}>>><[{<><>}{{}<>}]([[]<>]{{}()})>>])>>{{[{{{<<<>()>[{}()]>{<[]()>[<>{}]}}}}<(<[(
  {<[{<<({[({(([[]<>](<><>)))[[[{}()]<()[]>]<{<>{}}[()<>]>]})([<([(){}]{<>[]})<<<>()><(){}>>><([<>[]>([][]))(<<
  [[[[<<(<({(<[{(){}}[()[]]][[{}[]]{[]{}}]>([{[][]}([]{})][{{}[]}<[]()>]))[{[{()()}({})]({(){}}[<>[]
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  <{<{<{[{(((<(<[]{}>)([{}{}]({}{}))>([{[]<>}[[]{}]]<([]()){[]<>}>))<[(<[]{}>[()[]])]>)<{{[{{
  {{<([<{[(([(({[]<>}{()[]})<(()){(){}}>)[{({}<>)<[]<>>}<{{}()}<<><>>>>][{<({}<>)[()()]><<()<>>>
  [[[<([<<[[[{<<[][]>{()()}>[[(){}][<><>]]}{[{<>[]}[[]{}]]}]{<<({}<>)[[]]>[(<>[])]><<[()[]]<[]>>[{[]<>}({}{})]>
  {{{[{(<<{({{<{<>[]}>[{<><>}[()[]]]}[({()()})([<><>]<<>[]>)]}({[{{}[]}{{}[]}]}[(<[]()>[<>[]])({<><>}[(){}])]
  (<<[{[{[({<[{{(){}}<(){}>}{{()[]}[<>{}]}]{{(<>{})<{}>}{((){})}}>[{([<>()](<>{}))<{{}[]}[[]{}]>}{(<[][
  (<[[{<<{({<([<<>()>[<>()]]{{()<>}[<>[]]))>({<<<>()><()<>>>}({{[]<>}{{}()}}{<(){}><<>{}>}))})}<([<({[[]]{{}<
  ([((<[((([{<((()<>))[([])]>({(()<>)([]{})}([{}<>](()<>)))}{<[[[]()]([]{})]>}]({([{[]{}}][{(){}}{(){}
  (({{<[<{<{([<([]<>){()}><([]<>)<[][]>>]<<[()<>][[]<>]><{()()}>>)[(<[[]{}](<>())>{{{}()}{[]()}}
  
"""

Module

defmodule Day10 do
  @left_brackets ["(", "[", "{", "<"]
  # @right_brackets [")", "]", "}", ">"]

  defp chars_match?("(", ")"), do: true
  defp chars_match?("[", "]"), do: true
  defp chars_match?("{", "}"), do: true
  defp chars_match?("<", ">"), do: true
  defp chars_match?(_, _), do: false

  # Part A
  defp score_invalid_char(")"), do: 3
  defp score_invalid_char("]"), do: 57
  defp score_invalid_char("}"), do: 1197
  defp score_invalid_char(">"), do: 25137
  defp score_invalid_char(_), do: 0

  def check_line_for_invalid(line) do
    check_line_for_invalid([:start], line)
  end

  defp check_line_for_invalid(_buffer, []), do: 0

  defp check_line_for_invalid(buffer, line) do
    [bracket | rest_of_line] = line

    if Enum.member?(@left_brackets, bracket) do
      check_line_for_invalid([bracket] ++ buffer, rest_of_line)
    else
      [last_bracket | new_buffer] = buffer

      if chars_match?(last_bracket, bracket) do
        check_line_for_invalid(new_buffer, rest_of_line)
      else
        score_invalid_char(bracket)
      end
    end
  end

  # Part B
  defp matching_char("("), do: ")"
  defp matching_char("["), do: "]"
  defp matching_char("{"), do: "}"
  defp matching_char("<"), do: ">"
  defp matching_char(_), do: nil

  defp score_missing_char(")"), do: 1
  defp score_missing_char("]"), do: 2
  defp score_missing_char("}"), do: 3
  defp score_missing_char(">"), do: 4
  defp score_missing_char(_), do: 0

  def check_line_for_incomplete(line) do
    check_line_for_incomplete([:start], line, [])
  end

  defp check_line_for_incomplete([:start], [], closing_chars), do: closing_chars

  defp check_line_for_incomplete([char | rest_of_buffer], [], closing_chars) do
    check_line_for_incomplete(
      rest_of_buffer,
      [],
      closing_chars ++ [score_missing_char(matching_char(char))]
    )
  end

  defp check_line_for_incomplete(buffer, line, _closing_chars) do
    [bracket | rest_of_line] = line

    if Enum.member?(@left_brackets, bracket) do
      check_line_for_incomplete([bracket] ++ buffer, rest_of_line, [])
    else
      [last_bracket | new_buffer] = buffer

      if chars_match?(last_bracket, bracket) do
        check_line_for_incomplete(new_buffer, rest_of_line, [])
      else
        :invalid
      end
    end
  end
end

Part a

input
|> String.split(["\n", " "], trim: true)
|> Enum.map(&String.graphemes/1)
|> Enum.map(&Day10.check_line_for_invalid/1)
|> Enum.sum()

Part b

input
|> String.split(["\n", " "], trim: true)
|> Enum.map(&String.graphemes/1)
|> Enum.map(&Day10.check_line_for_incomplete/1)
|> Enum.reject(&(&1 == :invalid))
|> Enum.map(&Enum.reduce(&1, 0, fn x, acc -> acc * 5 + x end))
|> Enum.sort()
|> then(&Enum.at(&1, div(length(&1), 2)))