From 6ba33d1710d2bc4d4241aa756dbb84e8130bbf33 Mon Sep 17 00:00:00 2001
From: Dustin Swan <dustin@dustinswan.com>
Date: Fri, 10 Dec 2021 17:02:02 -0500
Subject: [PATCH] day 10

---
 day10.rkt      | 53 +++++++++++++++++++++++++++
 day10.test.txt | 10 ++++++
 day10.txt      | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 161 insertions(+)
 create mode 100644 day10.rkt
 create mode 100644 day10.test.txt
 create mode 100644 day10.txt

diff --git a/day10.rkt b/day10.rkt
new file mode 100644
index 0000000..925a915
--- /dev/null
+++ b/day10.rkt
@@ -0,0 +1,53 @@
+#lang racket
+
+(define data (map string->list (file->lines "day10.txt")))
+
+(define pairs (list (list #\{ #\}) (list #\( #\)) (list #\[ #\]) (list #\< #\>)))
+(define opening (map first pairs))
+(define closing (map second pairs))
+
+(define (go input stack) ; returns the incomplete list OR the first broken bracket if corrupted
+  (if (= 0 (length input)) ; if we've run out of input..
+      stack ; we've got an incomplete chunk. return the stack
+      (let ([x (first input)] [xs (rest input)]) ; grab the first element of the input
+        (if (member x opening) ; if it is an opening bracket
+            (go xs (cons x stack)) ; push it on the stack
+            (let* ([y (first stack)] ; otherwise, it's a closing bracket. grab the top of the stack..
+                   [matching (second (assoc y pairs))]) ; and find its matching closing bracket
+              (if (equal? matching x) ; if they match..
+                  (go xs (rest stack)) ; remove it and recurse
+                  x)))))) ; if they don't match, return the offending bracket
+
+(define part1
+  (let* ([res (map (λ (x) (go x '())) data)]
+        [bads (filter (λ (x) (not (list? x))) res)] ; filter out the lists - they're the incomplete chunks
+        [costs (list (list #\) 3) (list #\] 57) (list #\} 1197) (list #\> 25137))]
+        [points (map (λ (x) (second (assoc x costs))) bads)]
+        [total (apply + points)])
+    total))
+
+part1
+
+; PART 2
+
+(define (complete input stack) ; find the necessary closing brackets to complete the chunk
+  (if (= 0 (length input))
+      stack
+      (let* ([x (first input)]
+             [matching (second (assoc x pairs))])
+        (complete (rest input) (cons matching stack)))))
+
+(define (score chunk)
+  (let ([costs (list (list #\) 1) (list #\] 2) (list #\} 3) (list #\> 4))])
+  (foldl (λ (x acc) (+ (second (assoc x costs)) (* 5 acc))) 0 chunk)))
+
+(define part2
+  (let* ([res (map (λ (x) (go x '())) data)]
+         [rev (reverse res)] ; reverse so we can use `first` & `cons`
+         [incompletes (filter (λ (x) (list? x)) res)] ; filter out the lists - they're the incomplete chunks
+         [completing (map reverse (map (λ (x) (complete x '())) incompletes))] ; un-reverse it
+         [scores (map score completing)]
+         [sorted (sort scores <)])
+    (list-ref sorted (/ (- (length sorted) 1) 2)))) ; find the median scoring chunk
+
+part2
\ No newline at end of file
diff --git a/day10.test.txt b/day10.test.txt
new file mode 100644
index 0000000..b1518d9
--- /dev/null
+++ b/day10.test.txt
@@ -0,0 +1,10 @@
+[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]
diff --git a/day10.txt b/day10.txt
new file mode 100644
index 0000000..6b0ede5
--- /dev/null
+++ b/day10.txt
@@ -0,0 +1,98 @@
+{<{[<((<[<({<{(){}}(()())>[<<><>>((){})]}(<<{}{}>(<><>)>))(<[(<>{}){()()}]{{{}[]}(()())}>[
+((<{[<([<<{[<(()())([]())>)<<<{}{}>{[][]}>{<<>>(()[])}>}<(((()[])[{}<>])[<[]{}>{{}[]}])[[({}{})
+({(<[([((<(<[(<>{}){()[]}]<[[]<>]<(){}]>><{(<>())[<>{}]}{(<>[])(<>{})}>)([(<(){}>[(){}]){{()[]}{<>{}}}][<<[]
+{{{[(([{{{[{[(()())[<>[]]]{([]{}){()<>}}}]{{{((){})[[][]]}[[{}{}]<[]()>]}(<(<>()){{}{}>>([{}()
+[<{{{[[(<[(([<{}[]>{()()}][[<>{}]]))]([<<{{}[]}>>([(<>[])<(){}>][[{}{}](()())])]{[{[<><>]}((<>{})[
+{<[<[[<<(<<<<(<>[])(<>[])>{([]())}>[{{[]()}}<({}())[<>()]>]>{[((<>{})[[]<>])([()<>]{<>()})](((<>()
+([({({[{(([<[<[]>]>]<<({[]()}<[]<>>)[[()[]]{[]{}}]>>))((<<{<<><>>}{(<>{})<[]()>}>([[<>{}]<<>{}>
+{(<([{{{{(((({{}[]}))){[(({}<>))({<><>}<[][]])][<<[]{}>[{}{}]>{<[]>{[]{}}}]})({[{([]<>)([]<>)}
+{([{{{(([<[[[<(){}>{()[]}][([]<>)<[]{}>]]<{(<>())[[]()]}[{(){}}[()<>]]>]([({[]{}}{()[])){{<>()}{()[]}}])>[<[
+[([{<{(<({<{[[<>{}][<>[]]]<{{}<>}<{}{}>>}[({()[]])[[<>()]({}<>)]]>{<([{}<>]<[]<>>)[{[]()}{{}[]}]>[[{[][]
+{{<(<{(<[<(((<[]<>><{}[]>))({(<>{}){[][]}}([[]()]({}<>))>)>[((((()<>)<<>[]>){(<>{}){<>{}}})(<({}(
+{{[{<{<([{[<{[{}{}]{(){}}}{{[]<>}<()[]>}>]<[({[][]}<{}<>>)(<{}{}><[]()>)]<[{<>{}}(()())]([[]{}]<[]<>>)>>>[{[{
+<(([<<{{<(([(({}{})[[]{}])[<{}>(<>{})]]<([{}{}]{()[]})>))({(<(()<>)<<><>>>(([]<>)))}<<<[()
+<<<(({{([{({({()()}<<>[]>)<{()[]}[<>()>>}){[<[<>{}][<><>]>[{()[]}[<><>]]]<<[<>[]]{<>()}>>}}[(<[[(){}](()
+<<[[{{([(([([[<>{}][(){}]])]{({{()}(<>{})}{{{}<>}{<><>}})(([<><>])({{}[]}<<><>>))})([{({()<>}<[][]>)}]))
+[(<<<<<{[<({[{{}[]}<()<>>]<[{}[]][[]<>]>})>[<<{(()())({}<>)}{({}())(<>[]]}><<<{}<>>([]<>)><[
+<<({({{([(<([[{}()]<[]{}>]<<<>()>>)><{(<{}<>><{}()>)<{(){}}[<>]>}{([[]{}][[]<>])<({}()){{}[
+{<{([[[[[{<<[[{}{}]([]<>)]{{{}()}[<><>]}><[<()()>[{}{}]](((){})<()>>>>}]<{({{([]()){{}<>}}<{<>{}}({}{}
+{[{[[<[((<(<<{<>}{()[]}>><{<<>[]>[()[]]}{{()()}[()[]]}>)(({[[]](<>[])}{({}())<{}()>})([[{}[]]<[]()>][{
+[{[(({[{{([[[<()()>{{}{}}]{([]<>){<><>}}]](<<<(){}>(()())>{[[]]{<>{}}>>))<[<((<>{}){(){}}){[{}<>]}>([[<><
+<{<(<([(<[({<<[]()>[[]{}]>(<{}<>>)}(<[{}[]][{}[]]>{<{}[]>[(){}]}))[<(<[]<>>{{}<>}]([[][]]<()<>>)>{({{}<>}[<>[
+{({({{<({[{[{<<>()>[[]{}]}](([{}<>]{()()})[([]()){[]()}})}[[((()())[()<>])(<<>{}><{}>)]]]<([{([]
+(<[([{({<([<(([]<>)<()[]>){{<>{}}[()()]}>])(([({[]()}<{}{}>)][<{{}[]}({})>[[<><>][<><>]]])<[({()[]}[[]{
+{{{<{{[[{[[<({[]()}{()[]})<[<>()][()()]>>(({{}{}}))][({[(){}](()[]]}){{<<>()>({})}{<{}[]>[{}<>]}}]]{[<
+{<([((<{<<<{(({}{})<<>[]>)(((){}){[]})}{({[]<>}[[]{}])<[{}[]][()()]>}}[{([<>()][<>{}]){(<>
+{([([(({[<[[[(())(<>[])]{[()()][<>]}]]>([{[(<><>)(<>())]<(()<>)[<><>]>}({{<>{}}({})}([{}][
+([[[({[{{<{{{[{}()]{(){}}}[{()}({}[])]}[{[[]<>>(()[])}<{[][]}{[]}>]}>}}]}{[<[[[[(({}{}){{}[]}
+<[{<([<({((([[<>{}]([]())]<[()[]]<()<>>>){<<{}{}>[<><>]>[((){}){{}<>}]}))}({[({[()())(<>[])}{({}())}){([()[]
+{([[{[<<[[<{([<>()][{}{}])<([]{})(()[])>}{{{()()}{[][]}}<[[]{}]<<>{}>>}>(({<()()>({}())}[{<>[]}({}<>)])([[<
+({[<{{[<{{(((([]<>){<>()})([()<>]([]{})))){{<{()()}[{}<>]>}({<{}[]>}{([]<>)<{}[]>})}}<<([{{}()}[{}[]]]<{(
+<({{([{[({<([({}())[()[]]]{([]{})})(([[]{}]{{}[]})([{}()><()<>>))>(<(({}{})<{}{}>)[{<><>}{[]
+[{[{<{([[[<[[{[][]}(<>{})]{{[]<>}[{}{}]}]><{({{}()}<[]()})}>]{{(<[[][]]{[]()}>{(()())(<>[])})(
+(<{(<[[<{[[<<([]<>)<{}{}>>({{}[]}({}()))>]({([[]<>]([]())){[<>{}]<{}()>}}[{({}())[(){}]}(({}{})[[]]
+<[<<([{[{<{{<[[][]]<<>[]>>({<>{}}[<><>])}([[{}<>]<()()>][<[][]>(()[])])}[({[()()][[]()]}[{{}()}<[]<>>])]>{<
+<(([[{(([[([[{{}()}{[]}]]<((<><>}({}[]))((()())[()[]])>)[{{<[]<>>((){})}}<(<(){}>{{}[]})({()}{{}<>})>]]<[(<{
+[{<(((<(<({(({{}()}{<><>})[{[][]}{(){}}])({{[]{}}[<>{}]>)})>((([<(<><>){{}<>}><[<>{}]>]([[<>[]][{}{}
+[<{{({([({({{{()<>}([][])>}((({}<>)(()[]))<(<>()){{}<>}>)){[([()()](<>[]))]{({[]}[[]{}])([[]<>
+{({[<{(<<([[[<{}{}>[{}{}]](<<>>(()))]{[([]<>)<{}{}>]<[<><>]>}]<[[{{}<>}<<>{}>][([]<>)<(){}
+([{{{[[(<<[<[[<>]{[]}]((<>{})({}[]))>({{()[]}<<><>>}{{<>{}}({})})]{{{{[][]}<{}()>}}<[[<><>][{}<>]]<
+[<{<{<[{{[([(([]<>))[{<>()}<{}{}>]]{[<<>{}>[(){}]){<[][]>[<><>]}})](([<([]{})[{}()]>(({}())(<>{}))]
+[<[<{(<(([{<{([]{}){[][]}}><{[{}[]]([]<>)}[[()[]]<()()>]>}][{(<[(){}]{()<>}><<[]()>[[]()]>){[[<>[]](()[])
+<(<<<([[<([[({[]<>}<[]()>){{<>[]}[{}{}]}]([[[][]]<[]()>])]<{{(<><>){<>[]}}}{(<[][])(()[]))[([]{})[[
+(([{<{{([<<{({[]{}}[()[]])[<()()><()[]>]}[(<()>[()()])[[<>[]]]]>>{{{{<[]()>[()<>]}}{{<()[]>[()[]]}<[[][]]
+(<<[([[{{({<[([][])<{}()]][<()()>(()())]>})}<([[{(()<>)<[]()>}((()[])[<>{}])]]([<{(){}}({}<>)>][<
+[<<((<[<<{(((({}()))({<>{}}([]<>))){{<()<>><{}[]>}{(()())}}){({([]<>)<<>{}>})}}<{{<[()][<><>]>{{[]
+<{[<[((([{<{{{<>[]}[[]()]}([<><>])}>((<<<>()>({}<>)><[{}[]]<()[]>>)[{{[][]}{()<>}}[{()<>}(()[])]])}(([<{{
+{<{<[(({([<[<[[][])([]{})>[{(){}}[[]<>]]][(<{}<>>{()<>}){[<><>]{{}[]}}]>([[<[][]>{[]<>}]({[][]}(()()))]{
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+<<[(<([<(({[{({}{})}<{()<>}{<>{}}>][([[]()](()<>))]}[[({{}()}<[]{}>)[<[]()>[()()]]]((<{}{}
+<<{[{[<{{{([<<<>{}>{()[]}>({{}[]}<<>{}>)][[<()[]>[{}[]]]({()<>}(()()))])[<<<<>()>{[]{}}>><{{[]{}}<()<>>}(<<>[
+[{{<({[([({{{(()())[<><>]}{[()()][(){}]}}}{[([<>[]])[{[]()}((){})]]([<[]{}>(()<>)]{[<>]})})(<
+<<<{{(({<{<[<<<>{}>>(<<>[]>{()()})]<([()<>])>>[(<({}[]){{}[]}>{[{}{}][[]()]})[<[<>[]]<()[]>>(<
+[([<<<(<[[[[[([]{}){{}()}}<<[]()>{[]}>][([<>[]]({}))[(()<>){()()}]]]]]>{[([[<([]())<{}<>>>({<>()}
+[([{{[[(({[<{[{}[]]{[][]]}<{<>()}[<>[]]>>(<{<>()}<[]()>>)]}))<<<<<{{()[]}{{}[]}}[<<>{}>]><{[{}<>]{(
+[{{{<((([{([{[[]()][<>()]}([[]()]{{}()})]{([{}{}](<>{}))({()<>}(<>{}))})<[({(){}}[()<>])}>}(
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+<[[[[({([[{<[{{}()}]{(()<>)<[]()>}>{[{<>{}}(()[])][{()[]}<()()>]}}]]<{[(({<>{}}{<>()})<[[]()]<<>{}>>)<((()[])
+({{{<{[({[[[<{()<>}<<>[]>>{[[]<>][<>()]}]([(()<>)[[]()]]({{}[]}(()[]))]]][{{{<<>>({}<>)}<<<>{}
+[{[((<{<([[{<<()[]>[[][]]>}<{({})}[<{}[]>[[][]}]>]]<<{(([]<>)[[]()])}<{<{}()>{[]}}{[()[]]({})}>>
+[{([[{[({<[<(<<>{}>({}[]))([{}<>]{(){}})}({<[][]>}{[()()]<{}[]>})]<<[<(){}>[<>{}]][<<>{}>({}{
+[<([{<<[((([<[<>()]({}())><([]{})<{}[]>>]))[{[[[[]()]]]}{{[{[]()}([][])]{<[][]>{{}()}}}}])<(({{(<>()){
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+<<{[(([{<((({([][]){[]<>}}{({}())}))({[<<>{}><<>>]}{<[<>{}](()())><<{}[]>{()<>}>)))({[<(<>[
+<[<((<<[[<[((([]<>)<(){}>)[<(){}>])({<{}{}>{<><>}}<(()())<[]{}>>)]{{({(){}}(()[]))}<({<><>}({}()))>}
+[<{(<([{[({[{({}{})<{}()>}[{[]<>}({}<>)]]})[<[([{}[]][()[]])((<>()){{}<>})][[[(){}][[][]]][<
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+{<{{(<{{<[[({<<>>}<[(){}]({}())>)[<{()<>}[{}()]>[({}[])<()()>]]]]{<[({<>{}}{[][]})]{[(<>{})({}())]}
+[<[<{<<({[[(((<>())[{}<>]))<(({}[])(()[])){{{}{}}[[]<>]}>]<[(<{}{}]{{}{}})<(()<>)>][[{<>{}}<[
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+[[{[<<<[{[[<({<>()}((){})){{<>[]}<(){}>}>[<(()<>)({}<>)>{<[]()>(<>)}]]]{<<{[<>[]]>>(<<{}()>(<>())>(
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+{(<(<{<<([<<<[{}{}]<{}{}>>><[{<><>}{{}<>}]([[]<>]{{}()})>>])>>{{[{{{<<<>()>[{}()]>{<[]()>[<>{}]}}}}<(<[(
+{<[{<<({[({(([[]<>](<><>)))[[[{}()]<()[]>]<{<>{}}[()<>]>]})([<([(){}]{<>[]})<<<>()><(){}>>><([<>[]>([][]))(<<
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+{<{(<[<(<<<{<[()<>]>{{()[]}}}<<([]<>)[()<>]>>>[{[<<><>>[{}<>]][<<><>>{(){}}]}[{[[]()]{<>()}}
+<[[<{<<[{{[[(([][])[[][]])<({}<>){{}[]}>]](<<({}[])[[][]]>((<><>))>[([()[]]((){}))])}}{[([((<>())
+{(<{[[((<<<{<{<>{}}([]{})><{()}>}[{(()<>)[[][]]}{<{}{}><{}{}>}]]<[[<{}()>]<([]{})>]{{[<>()]{{}{
+<{<{<{[{(((<(<[]{}>)([{}{}]({}{}))>([{[]<>}[[]{}]]<([]()){[]<>}>))<[(<[]{}>[()[]])]>)<{{[{{
+{{<([<{[(([(({[]<>}{()[]})<(()){(){}}>)[{({}<>)<[]<>>}<{{}()}<<><>>>>][{<({}<>)[()()]><<()<>>>
+[[[<([<<[[[{<<[][]>{()()}>[[(){}][<><>]]}{[{<>[]}[[]{}]]}]{<<({}<>)[[]]>[(<>[])]><<[()[]]<[]>>[{[]<>}({}{})]>
+{{{[{(<<{({{<{<>[]}>[{<><>}[()[]]]}[({()()})([<><>]<<>[]>)]}({[{{}[]}{{}[]}]}[(<[]()>[<>[]])({<><>}[(){}])]
+(<<[{[{[({<[{{(){}}<(){}>}{{()[]}[<>{}]}]{{(<>{})<{}>}{((){})}}>[{([<>()](<>{}))<{{}[]}[[]{}]>}{(<[][
+(<[[{<<{({<([<<>()>[<>()]]{{()<>}[<>[]]))>({<<<>()><()<>>>}({{[]<>}{{}()}}{<(){}><<>{}>}))})}<([<({[[]]{{}<
+([((<[((([{<((()<>))[([])]>({(()<>)([]{})}([{}<>](()<>)))}{<[[[]()]([]{})]>}]({([{[]{}}][{(){}}{(){}
+(({{<[<{<{([<([]<>){()}><([]<>)<[][]>>]<<[()<>][[]<>]><{()()}>>)[(<[[]{}](<>())>{{{}()}{[]()}}