44:["$","title",null,{"children":"Advent of Code 2017: Day 9 | Matt Cowan | Observable"}] 4c:Tac2,md` A large stream blocks your path. According to the locals, it's not safe to cross the stream at the moment because it's full of garbage. You look down at the stream; rather than water, you discover that it's a stream of characters. You sit for a while and record part of the stream (your puzzle input). The characters represent groups - sequences that begin with { and end with }. Within a group, there are zero or more other things, separated by commas: either another group or garbage. Since groups can contain other groups, a } only closes the most-recently-opened unclosed group - that is, they are nestable. Your puzzle input represents a single, large group which itself contains many smaller ones. Sometimes, instead of a group, you will find garbage. Garbage begins with < and ends with >. Between those angle brackets, almost any character can appear, including { and }. Within garbage, < has no special meaning. In a futile attempt to clean up the garbage, some program has canceled some of the characters within it using !: inside garbage, any character that comes after ! should be ignored, including <, >, and even another !. You don't see any characters that deviate from these rules. Outside garbage, you only find well-formed groups, and garbage always terminates according to the rules above. Here are some self-contained pieces of garbage: - <>, empty garbage. - , garbage containing random characters. - <<<<>, because the extra < are ignored. - <{!>}>, because the first > is canceled. - , because the second ! is canceled, allowing the > to terminate the garbage. - >, because the second ! and the first > are canceled. - <{o"i!a,<{i, which ends at the first >. Here are some examples of whole streams and the number of groups they contain: - {}, 1 group. - {{{}}}, 3 groups. - {{},{}}, also 3 groups. - {{{},{},{{}}}}, 6 groups. - {<{},{},{{}}>}, 1 group (which itself contains garbage). - {,,,}, 1 group. - {{},{},{},{}}, 5 groups. - {{},{},{},{}}, 2 groups (since all but the last > are canceled). Your goal is to find the total score for all groups in your input. Each group is assigned a score which is one more than the score of the group that immediately contains it. (The outermost group gets a score of 1.) - {}, score of 1. - {{{}}}, score of 1 + 2 + 3 = 6. - {{},{}}, score of 1 + 2 + 2 = 5. - {{{},{},{{}}}}, score of 1 + 2 + 3 + 3 + 3 + 4 = 16. - {,,,}, score of 1. - {{},{},{},{}}, score of 1 + 2 + 2 + 2 + 2 = 9. - {{},{},{},{}}, score of 1 + 2 + 2 + 2 + 2 = 9. - {{},{},{},{}}, score of 1 + 2 = 3. What is the total score for all groups in your input? `4d:T417b,input = `{{{{{{!!!!!!">},{!!>}},{<},!,!!!>}e!!!>{!>{,i!!!>,<}>},{e'!!!>,!<'o'!!{au!{!>},<}!<>}},{{{!!!>!>!>,}}},{{{},{!>,},<}!!!>e>,{{,<,a,<'!o'!>!u{!!!>,<,!!!>>}}},{{{}{e!!o!!,o'{},{!!{a!!!><},{{<>}},{{{{<{!>},{{}}},{{},{<,!u!e!>},!!!>,!!!>!}}"{>}}},{}}}}}},{{{},<,!!}},{<'"!,!!!>},,oo">,<>},{{{},<''!>},,},},},{{},{,}},{{!!,!!iau!>""!>},e{i}>,<"!!>},{{<<}"!ou!!o,>}}}}},{{{{{'!!{!>,<>},},},"<,!!!>u'!>},a>},{{{<">},'e!>,<<{,!!a{!>},}}},{{{}},{{{},,>}},{{<"!"'!>,<!>},<>}}}},{{},!!i,!!ao!>,},<>}},{{{{},e",!i!>i,}!>!!!!!>!!!!!>>},{!!'!!!!!!!!!!!>,'i!!aau,!>!!>}}},{{},{<,!!!!,o!!!>},,},<",!!!>u!!'eou!>>,{{},{!"{},<}}>}}}}},{{{{{<>,},},},{{{<,!o!}>}},{{!!!>ui!>},,<',!o>},{},uiui"}!!}!!!>a}>}}},{{},o!>>},,!u>}}},{{{,,<,'e"{io!>!>ie>,},!!e!>!>,>},{{,},,<>},{}},{<>,,e{{}uu>}},{{{,<'!>,},e!!}!!!>}>},{,oo>}},{{{}},{!!!>'>,}},{{{<"!!!'!!,!>,<,!"!>},<{!!,}{!!}!>o!!u>},{{,},<,!!e}}},<>}},{{{{{{},{}},{<"!>,,,<{},},{}},{{<},},},}}}},{{{{{{{}},{}},{{},{{a!!i}}o!!!>!>,<<}a'!!!!!>},},},{!>,,},<<">}}}},{{{}},{<>,{}}}},{{'o},{{}}},{{<!!,,!!!!!>{"u!>}!a>}}},{{{},<'!>"}!>,>,{{},i}}},{{},{{},},},<<'!!i!!!!!o!!!>i},},}}},{{i{>,<{u,!!e!!{"'o!!!>,},,<>},{,<""!!!>!!!>!!!!e'!!!>!>},<}>,{{},{{<'e!!!}!!i}{a!!!>{!}!!!!!a>}}}},{,,<{>}}},{{<>},{{{<"!!!!,}}!!!{!>},,}}}}},{{,{},<"'>}},{{}},{{{{a!!a!!!>>,},i,}!!""!o!!!>>},<'!!}!>,<,i!{i!>,,<">}}},{{{{{},}}}},{,!!"<<>,<"!>},,},},{{{{}},ei!!'!>,<>},{}}}},{{{,<{!>},{}},{{{<'i>},!!o!}!!!>,<,a>}},{{},{{<{iu}"!>,}}}}},{{{!!!>!!!>,,,<"!!>},{}}}},{{{}},{{{},{}},{<'u!>},},,!!e>},{{{}},{,<"u!}a<}>,{{,{!!{!>,<},>},}}}},{{<'!>},},{,,}"{!!}>}}},{{{{{<}!u>},{oa{!!!!!>o{!!a!!!>!>,},<',!>{>}}}},{{{{{},<'"!!{,e>}},<<,!!!,!}i!!<',u>},{{{}},{!>},,!!!>!!!!!>!!!u!!>}},{{!>,,!!!>,e!><}!<>}}},{{},,{}}}}},{{,{}},{{},{uou""!>,},},}}}}}},{{{{{,!>},a!>},<"{eeu!a{!>,<>,>}}},{{{{>},<!,{'o!>},!!!>,},{{!>},},<}!!,!!a{ie{},{{{}},{{<>}}}}},{{<}i!!!>!>},<}"e!>,,{<'!>!!!>a!!{'oe}!!oo>}},{{,u!!!>!!!>},}},{<,}!!o!>,,!>},{,{!!o}>}},{{{!!!>!>a,,,!!oe,o!>!!'!!!>>,{<}"!!<"i!>,,}},{},<'>},{{<",!!!>!>,<,a!}<"}!>!!!>!>},,<>},,}},{{{{},{{{{},},<,o!!!>"!!!>!i>},{<<}oa!ae,},u!>!e"!!!!!>{u},,<>},{{},<>}},{{u},{!!!>,<{!>,},<u>,{}},<>},{{{{},{}},{!!!!!a!!!>!e,"!!!>>,{,},}},{{,<''!>,<,{<{!>,<u,e,!>!!!>},<>}}}},{},{{!!!>i{!!o!!iu,!!!>>},{{,<>}}}}},{{},},'!!i"uuu!>},<"{>}}},{{},{}},{{{}},{}},{{{{,<>}},{{{{{}},<>}}},{{,ai!!!>}>},},<'}e"<"''!>>}},{{{},,}},{{{{{},>}},!'!>o!io>}}},{{{!!!!ei}!>,<'!>,<,!>},<{!>!>},<{>}},{<{!>,!>,<>,,},<!>!>,,!!u!io>}}}}}}},{{<>},{{{<>}},{{,<,iea{>},{}}}}},{{<}<,},},<>,<}ii!!!>},<}},{{{!>,<,'!!<>,{{},<},<'a!!!>a!!>}},{,},<,a!!!!!>aau!>},},}},{{},i!!!>!!!>!!a!>,<}!!!>!!'!!>}},{{{{<,,oa!!!!!>u!!'ee!!!!!>""a{>},{}},{{,{},,,u"ou,{,>}}}}}},{{{,},e!>},'o!!!>!!{a!!!,>}},{{{{>}},{{},{{{,!!!!!>'i!!!!{,""!,iui!!!>>}},!!!>},},<"!>},,>}},{{{<<}u!{e>,{>}}}}},{},{}},{{>,{}}},{{<}>,{<},}},{{},{!e!>},,},},},<>}},{!>,<a!'!!o{!!,!>},},}}}},{{{{{!>,!><<"!u"!!!!!!{!!>},{}},{},{{o!!o",>,{!!!>},},{!>,<',!!!>ei!!!!>,{,,,<,i!!ei!>{!!!>}}}}},{{},{{},<>},{{<}!o!!!>u,u!>,,<>}}},{{{{{{{{i>}},{{!>},<,}},{<>,},<{>}},{{{{<"e!,<,!>},},{}},{{{{},<'!>,,{<{!><}a'!>,,<,!!!!,e!!i{<'!>,,{!>,<>}}},{,<}!!<",}}},<,{o!>!i!!oo"!>},},{{{},'{}!!!>,<{!!u,>},,},<{!>,<{!!i!>e>}},{{},{!e!>,},<>}},{{},{<{!"">}}},{{{{},},{}},{{{<>}},<""a"!>,!!}!>,>},{,{}}}},{{"e,<>}}},{}},{{{<"!>,},{}},{{{<">,{<>}},{!!<>}}},{!!!!!>ooa!!}!!!>,!>,}'!>},<>,,,u>}}}},{{{{},<,'i!>oe{!!!!}>},{{,<'!!!>!>},!!!>>,{!>!>},<>}}}}}},{{{},<,{'o!!o!>>},{},<>,{{{{{!!!>,},<}!>,!!,<'o!>},,}},{}}},{}}},{{{},<,<'u>}}},{{{},{},<}!!iau!!a}o!!!>,>},{{},'}!!{!!}i"'!a,!>},<}},{{},{{e>},{}}}},{{{},<>,},'o!{>},{{e!>,<,!!!>i!!!>{!{u'!>,<,"!>,},{{},{<,e!!{{!!u!>}!e!!i{ie}!>},}}},{{{},{},<'oe"o!>,<>}}}},{{},{}},{i!!{!>,,,<"{',{}}},{{,,},,,},},!>},,!!!>>},{},,o!!!!!>o},}}},{{{{<}!>,<}oi>},},},{{{>}}}},{{{},},<>,!!}!!!!!!{i!!a>},{}},{{},{{{,<{}}a!!!!!>iu!>!!ie,!!!>i!>,<{>}},{{{},<>},{,!!!>!!e}"!!>}}}},{{},{{o''"!>!ue}!>!!<"}!>!!!>!!{>}}}},{{{<"e>},{<'!i!>,,{},>}}},{<"<"}u,!>e!!u'{!>},},{}}},{{},<>},{}},{{{>}},{},{}i!>>,{!!!!eo}o,!}oia!!!>!!!>,}}}}},{{{{{<>},{}},{{{,!!},<>,<>},{{<}a!!!>",!>,!>,},},}},{},,>,{},,,}}}},{{{{,},,{,}}}},{,{}}},{{},{{<}uo!!{,'>},{,}}}},{{{<}<{>}},{{{<},!!u!>>},},<{"!>,},!>},,{e!>,<'oa!!!>u>},{{{},'ea'i>},ii!>},,},,},>}},{{},{o'!>!>""!i!!!!e!!!>!!!}i>,<},,,!!i{!}a!!!!!!!>>}}}}},{{{}},{{{}}},{{{},<<{e{i!>,,<,!u>},{{}}},{{},{{{{,!!!>!!{!},<,<","!!o>},{>}}},{{{<!>,},<{},<},{}}},{},,e'>,<"!!!>,,>}}},{{<"}!>!>},!>,!!'a!!!!!>"!!!!o!!{"!>},>,{!u!!!>!!{!>!aaa,>}},{<,ee!!i>},{{{}},{{},<{!!}!!!>,,,}!>,},<{,i",<>}},{{,},<!>},,!>,<>}}}}},{{{},{{{<'o"<',,e>}}},{{{"o!>},}},{{},u,!}!>,<>}}}}},{{{{,,<>}},{{,{}},{<,!!e!>},>}},{{{},<}>},<{a!>!ao!!!>},},{{,!>"'e{!!!>,<,!}au!>},},{{{<{',{}o!e!>,<>}}}}},{{{{}}},{{{{!<}>},{,!><,!>!!!>!!!>},<>}}},{{<{>},{,},'!>!!{!!!>}!!>}},{{<!',}e!"!!!>!!!>a!ie!!!!!!i>,{},>,{}}},},<,!>"'i>}},{{},{{},<"'aueu!!u>}}}},{{{{!{!>u'e'!!e,iu>},{<','!>,},<}u"ue>}}},{{},,,!"i!!o!!{!>,,<}iu!{ou!u'"!!}!!<,!o"{>},{,<}!>a!!!>!>,,},<>,,'!!!a"'!!,<{!>,,},{{{{>}},{{},<}{}!!!>!!!!!>},e>},{<}u'<<",!e!>},,}},{{{},{}},{}}}},{{{,<"!!!>ea!>!!}!>oa!!!>,},},},<}!uii!!i!>},,,},{},{},<'u{u!!<'!!!>e}}},{{{{{{}},{!!},<'!!o>},{},{<}!!o!!!!u!!!"o{!!}!!{!>,,<'>}},{{<>},{{>},{},<>,{}},{{u!>},,},i!ou!>},<>},a!!!>}!!!!!!>}}},{}},{{<'u!oi}!!!>!>},},<>,},,},{{},},}},{{!!o"!!'i!>,e!>,<{!!!>"'o>,{}},{{},{<{}io}}!o!!!>},>}}},{{{<"!>{!!{!!!>!!!>{oa}'u!>},},<'!u!>!>u"'!e}!!!>'!!!!ee!!!!!!!!!!<>},{{,,<'<"o!!!>i!>!"!!i>,{}},{},},!!!>i!"u>}}}},{{{},{{!>,<{!!!>}>},{'!>,!!i!!!>,,<"!>a!>},<">}},{{u!!}>}}}}},{{{{{<!!!!>},{<>,},{{<>}}}},{{{}},{},,,,{,oa!>>}},{{!!!!{'<},e>}}}},{{{{{{},},},>},{{!>aa,<<}i!!e{a>,{,<},,<}a!>e!!!>!>,,<>}}},{{<'i{ea<<{>},{<{!!!>,>}}}},{{{{<{!>},,<<>},{,},!!<'!!oae<'>,{{,<">}}},{<},<>}}}}},{{{{{!>,},<}},!>,<<>},{!!},,!!{"!!!!"eo>}},{{{{,!!"{{u>}},{{<>,>}}}}},{{{a!>},!>,<{{!>},{>},{{{{,},<>},<>},{{!>!!i!>!>,<>},{<'<}}}}}},{{},{{<}},{<,">}},{{{!!!>{,!{,!!>},{{{{},e!>"}>},<,"!!{eu!!,>}},{}},{},{{{{{},>},<{{!>!!!"i!!e'!>},!!!>!!>},{{,<ii!!u!>,!>},},},{<{a!>},<>}},{{{!,<,!"e}}u>},{{{{<,>},{}},{{{{},<'>},,!>,,<,<,!!o!>}!!,!>},>}}}}},{{!o!>},'u>,},,'>},{{{{{{},<<"!>e!>,<,}u"!u{!>>},{<>}},{<'!>},<{""'{u,>}},{o!!!>,,"'!!!>},},,<}<>},{{{{{,,}},{,u!!a>,,!>!!>}},{{}},{}},{{{},<,},<,!!!>!!<>},{o"!>},<}!!!>!i"{!>},<,,!>!>,<>}}},{{'!!!>},ui{"{,a!!!,i!!u'!!>,{auo!!!>!>},,!>,<',<,o>}},{{{{,!!!>a>}},<},!!!>!!ae!!!e"!!}!!!>!!{!>,<>},{}},{{},}}}},{{},{{!!!>!>},},}}}}}}},{{{{{<}>,{<{!>!>,>}}},{{,<,>,{}}},{}},{{{<'!>},,!!{!>!>!>},u!{!>},<{<>}},{{io,>},}},{{!>o"!!"i<>},},,,<>}},{{{{}},},<,<<>},{{}},{{}}}}}}},{{<"!a!>},},}a<}uuo>},{{}},{{}}},{{'e'u!>!>},,<}!!!{!>,<>},{<"e'",e!e!o!!{>,{,}}},{{'u!!,u>},{!!}!!{!u}!>,},<>,{<,!!o{"!>,<}"a>}},{{"e!>{},i,}ue!!!>{{}!>>},<}i!>>}}},{}},{{{},{}},{{{!>,},},,},,<}},{{}}},{{,!aia!>},<{>,{<<,o!!}ao!>,,}},{<,!!!>!>},,},>},{,>,{<{!!"!i!e!!!u'!!e!>,<>}}},{{{{{,<{!!i!!o!a"ueo!}"!>a,}},{,{}}},{{!!!!!>aa!>},<>,{<>}}}},{o!>,},,{{},<}}{!o!e!!!},!>,<>},!!!!!>o}!>e!!>}},{},<{a{>}}},{{{,},!>!>},,>},{<{i,u!!!>,>,{}},{o!>},},}},{{},{<},{{{<,!}{!>,<}!!},<'>}},{{},!>,,<'!!!>,<,!>},<'{!!{}'>}}},{{{{{,,>}},{!>},>,{},},}}}},{}}},{{{<}'!!!!>,<<}'!!'{''!!>},{{{},!!!!!>u!!,e!"i!!!>>}},,!>},},{!>,<>},{!!{>,<"!!!>}},{{{{}},{{},{},>}},{{},{!>!>},<}u!>},<>,{{<}'{!>,}}}}}},{{{{}}},{{{},{<>}},{},{{}}},{}}}},{{{{{},,},{{<{!>,<},{{{{},{}}},{i!!a,!>,},a<{>,{}},{{{<>},,>},{<,o!!{,<}"u>}}},{{}}}},{{<>,<"',"<,!>},!!!>!!e}!!!>>},{!>},<"u!!!>>,,>},{{<"e{!e!>!>,!>},<,!>"'!!!!i!>!!'>}}},{{{{{{},{{<{e!!!>!>>}}},{{}}},{{},{<>}},{{},<'a!!!}{!!!>o,!ui!},,<'!>,<">},{<'}!>},<<>}}},{<"!>u!u},{{},},eu!',!!aui!!"<>},{{,,,!!"{o>},{<"!>,,<}u}!>},<>}}}},{{{<{{"!!!>!!!>!>,},<'uu!>!!!}{u,a!>,},<>},{{{},{{},{{!a'{u!!!!!u!!,!>,}}}}}},{{<},,!!!!!>!>},o!!!>!>},<''e!!<>}},{{!>},},{{{<{},!>},},<"!!!!'ou!!!>eu>}},{!>},<'!>},,{i>,{<{{{'!>ai'!!!>iie!<}!!!>!!!!!>},<}!!>}}},{{{{},},"i!>!!!!,!>,,u,,>},{}o{o!''o!!!>>}},{{!>>},}!!!>}},{}}}},{{{,<'u!i>}},{<>,<,}!>,<a''e!u}e!>},>},{}}}}},{{{{{},!!}u!>,<{,!!!>e!!},},},{{<'!!a!!,o'o!>,}},{<>,{{!>,e!!!>!!}i!!!{!!"!,,<>},{<>,{{}}}}}},{{i!!'>},{},{!}}!>a!a!>},<{!!!!!!,u!u>,{{<}'!!u!!!>',,!>,},<,<,io>}}},{{{{,!>,!!}!>,,},}},!ue}>},{<,!>},,,,<'>}}},{{{{,,},<{'a!!}!>,},<<>}}}},{{{{{{<"!!!>!!ue'"<'!>!>},,,<}>},},,}},{{<}oa>,<}},{{{{<"!!!!!>e,!!"!!!{!},,<{!!{>},{}}}},{}},{{{{{<,o!!!>!u!!!!iei!>},}},{<'{ai}ui!!u!>},<,}},{{{,},>},,,}!!!>{!>!>,{!>,<'e}>}}}},{{{{{},{{,!>,,},<<"!!!!!!!!!!!>{<>}}}},{{u!!i"!!u!!!>{a}oa{!a!>},<>}},{{{{},<"!!!>},<""a'!!o"ioa"}'>}},{}},{{}},{{},},}}}},{{{{,<>},{{},{{<>}}}},{{}},{{},{{},{{!'!!!>}{!>},}}}}},{{{},,!!a!!!o!>!>,},},,>},{{<,}!,e!>,,u<"!"!!>}}},{,}!!ea!,!>,!>,},},!>,,<>,<>},{{,!"e'<>},{},{<"{{iu,!>e!!!!,!>},!!!!!>,>}}},{{{}}},{{<>},{{}}}},{{{,,!!}}'",i!>{,<>},{!!ae,",},<>}}}},{{{{},{},<}o"!!!!!o!>,<,iu!!!!"!!'}}},{{{{}},{<<"}!!!>,},>}},{{{},},!!>!i!!'>},{},<}ee!uuu!!,!>},}}},{,<>,{!!!>,!>,<,,!!!>'!o"!<>}}},{{{}}}},{{{{{{<'o!!!>},<>,{}}},{},{{},}}}},{{{<}!o!!{"!'!!!>},aa"!!!>ieao>}}}},{{{{},uia!!!>!>,,u''io{>,{}},{,},o}!!iaa!>},<>}},{{,},<{ea!>!!!!!>>}},{{{},{ee!!i!!!>i!!!>,,!>,<>},{{<}u}',iai!>,<',!!au!>>},!>},!>,}},{{<>,},<,'!>",{o!!!>,}},{!>,<",oi}!!,<'>,{,},<{i!!,"!!e}!>!!!aao>,<}!!'>}}},{{!i!e},o,!>,,<,!i!>"<>,<"u}>},{{{{u!!!>e!!!,{{{}},{},<'{!a!>ue!!!>!>,<>}}}},,}!!!!!>,}},{{}}}},{{{<"u}!!!>!!!>o{!!!!{io!!!>e!,{,},<}"!!<"''e!!ao>}},!o!i!>,e!o>},{e!'o'<>,{iui!>!!o!>,},<>}},{{,},!!!!!>},},<'!>,,{!e',!",>}},{{{{>,,},},},},},{o!!!!!!o!!e>}},{{<>}}},{{{},},<"!o!!!>i!!!>!!e!!!>,!!!!!>ia<<'>}}},{},{{{},{{,!>,<,}}},{{{{}},{}}}},{{{{{<'!>a!!!!!>"!!!!!>},!!!>>}},{}},{,<,!>,<"!!!>u!!!!!>!!!>!>!<{>,<"!!!>,,<}'!!e!!'!!!!!>u!>"u>},{{},{},},!!!>},<>}}},{{{{{}},!!>},{{<,,o!!'!>},<>,{e>}}}},{,!>,<>,}},{{,a!>,,,a'!>,,<>}},{{{,,},<>,<"i}{!!!o'{,i!!,!>"u>}},{{,!!!>ea},}}}}}},{{{{}},{{{{}},{{{{,},<'>}},<}o}},{},,{}}},{{},{{{,'a!!!>'!!!!!>!>},<>}},<"e!>,},o!>},,>},{{,},<'},},,{}},{,!>},<>}}}},{{{{<}!>},!!>}},{{},,a!!>}},{{{i}'eeu!!!>!>'>}},{,<"!!!>,,},,{<{!i{e!>,ue!>},<{!>},<,!>,,{<,>}}},{{,<'!>},<}>}}},{{{{{<!!!>a!!ao!!!>,<>}}},{{,<>}},{{},},},,!>},!!'!>},,}}}},{{{{},},{{},<>},'{,!>,<<>}},{{{}},{{>}},{{<,i'o!!>},{,}}},{{i>},{>,{{u!!{!!{!>,!!>},{},}}},{{{{}},{{e!>},}},{{}}},{},{{!!a!>,,<{!!!>!!,!>',>}}}}}}}`4e:T41a,{ let groupScore = 0; let depth = 0; let state = []; let i = 0; while (i < input.length) { const char = input[i]; switch (state[state.length - 1]) { case 'group': if (char === '{') { state.push('group'); depth++; } else if (char === '}') { state.pop(); groupScore += depth; depth--; } else if (char === '<') { state.push('garbage'); } else if (char === '!') { state.push('ignore'); } break; case 'garbage': // swallow chars until we hit a closing > if (char === '>') { state.pop(); } else if (char === '!') { state.push('ignore'); } break; case 'ignore': // last character was a ! // swallow this char and pop this state off the stack state.pop(); break default: if (char === '{') { state.push('group'); depth++; } } i++; } return groupScore; }4f:[] 48:{"id":"f610131399aef1f6","slug":"advent-of-code-2017-day-9","title":"Advent of Code 2017: Day 9","thumbnail":"131848217b93e169d9171ea1335d848c8c6eb4944be57e213c08b24c1037b220","access_level":"public","create_time":"$D2018-12-08T18:40:05.086Z","update_time":"$D2018-12-08T20:10:20.610Z","view_time":null,"first_public_time":"$D2018-12-08T20:10:45.633Z","has_unpublished_edits":null,"fork":false,"stars":0,"starred":false,"owner":{"type":"team","id":"150d072324233635","login":"mpcowan","name":"Matt Cowan","avatar_url":"https://avatars-next.observableusercontent.com/e2099947d874f59a033405d9b14644227c3f8d11863e2bc35ca7b69242c72fd5","tier":"starter_2024","bio":"","followed_by_you":false,"follows_you":false},"version":40,"publish_version":40,"role":null,"authored":false,"authors":[{"type":"individual","id":"0d1ab105ae1b9374","login":"mpcowan","name":"Matt Cowan","avatar_url":"https://avatars-next.observableusercontent.com/e2099947d874f59a033405d9b14644227c3f8d11863e2bc35ca7b69242c72fd5","tier":null,"bio":"","followed_by_you":false,"follows_you":false}],"members":[{"type":"individual","id":"0d1ab105ae1b9374","login":"mpcowan","name":"Matt Cowan","avatar_url":"https://avatars-next.observableusercontent.com/e2099947d874f59a033405d9b14644227c3f8d11863e2bc35ca7b69242c72fd5","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":0,"collection":{"id":"b982a7315f3f2787","slug":"advent-of-code-2017","title":"Advent of Code 2017","owner":{"id":"150d072324233635","login":"mpcowan","name":"Matt Cowan"}},"type":"notebook","body":{"titling":"auto","title":"Advent of Code 2017: Day 9","cells":[{"id":0,"value":"md`# Advent of Code 2017: Day 9`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":2,"value":"md`## [Stream Processing](https://adventofcode.com/2017/day/9)`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":5,"value":"md`---\n## Part 1`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":7,"value":"$4c","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":10,"value":"$4d","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":12,"value":"md`---\n### Solution`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":17,"value":"md`Let's try to walk through the string with a state machine...`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":13,"value":"$4e","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":25,"value":"md`---\n## Part 2`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":26,"value":"md`\nNow, you're ready to remove the garbage.\n\nTo prove you've removed it, you need to count all of the characters within the garbage. The leading and trailing < and > don't count, nor do any canceled characters or the ! doing the canceling.\n\n - <>, 0 characters.\n - , 17 characters.\n - <<<<>, 3 characters.\n - <{!>}>, 2 characters.\n - , 0 characters.\n - >, 0 characters.\n - <{o\"i!a,<{i, 10 characters.\n\nHow many non-canceled characters are within the garbage in your puzzle input?\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":28,"value":"md`---\n### Solution`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":32,"value":"{\n let count = 0;\n let state = [];\n \n let i = 0;\n while (i < input.length) {\n const char = input[i];\n switch (state[state.length - 1]) {\n case 'group':\n if (char === '{') {\n state.push('group');\n } else if (char === '}') {\n state.pop();\n } else if (char === '<') {\n state.push('garbage');\n } else if (char === '!') {\n state.push('ignore');\n }\n break;\n case 'garbage':\n // swallow chars until we hit a closing >\n if (char === '>') {\n state.pop();\n } else if (char === '!') {\n state.push('ignore');\n } else {\n count++;\n }\n break;\n case 'ignore':\n // last character was a !\n // swallow this char and pop this state off the stack\n state.pop();\n break\n default:\n if (char === '{') {\n state.push('group');\n }\n }\n i++;\n }\n \n return count;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","tool":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W4f","stdlib":"1"}} 24:null