Day 8 solution

README.md

@@ -19,6 +19,8 @@ After generating a new package update [`main.go`](main.go) to include a `<day>`
 
 ## My Solutions
 
+These solutions are based on my input values provided to me. The inputs I was provided are also included in this repo.
+
 ### Day 1
 
 ```sh
@@ -82,3 +84,12 @@ The solution for "seven" is:
 Used 357353 fuel to align
 Used 104822130 fuel to align
 ```
+
+### Day eight
+
+```sh
+$ ./aoc2021 --eight
+The solution for "eight" is:
+There were 476 instances of digits 1, 4, 7, or 8
+The sum of the decoded output values was 1011823
+```

eight/display.go

@@ -0,0 +1,195 @@
+package eight
+
+import (
+	"bufio"
+	"os"
+	"sort"
+	"strings"
+)
+
+const (
+	one   = 2
+	four  = 4
+	seven = 3
+	eight = 7
+)
+
+type output struct {
+	signals []string
+	outputs []string
+}
+
+type display struct {
+	outputs []output
+}
+
+func (d *display) load(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		o := output{}
+
+		insOuts := strings.Split(scanner.Text(), " | ")
+
+		o.signals = strings.Split(insOuts[0], " ")
+		o.outputs = strings.Split(insOuts[1], " ")
+
+		d.outputs = append(d.outputs, o)
+	}
+	return nil
+}
+
+func (d *display) uniqueOuputs() int {
+	count := 0
+	for _, o := range d.outputs {
+		for _, s := range o.outputs {
+			switch len(s) {
+			case one, four, seven, eight:
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+func (o *output) decode() (value int) {
+	decoded := make(map[string]int, 10)
+	twoThreeFive := []string{}
+	zeroSixNine := []string{}
+
+	sortedSignals := []string{}
+	for _, s := range o.signals {
+		segments := sort.StringSlice(strings.Split(s, ""))
+		sort.Sort(segments)
+		sortedSignals = append(sortedSignals, strings.Join(segments, ""))
+	}
+
+	// Find known digits
+	for _, s := range sortedSignals {
+		switch len(s) {
+		case one:
+			decoded[s] = 1
+		case four:
+			decoded[s] = 4
+		case seven:
+			decoded[s] = 7
+		case eight:
+			decoded[s] = 8
+		case 5:
+			twoThreeFive = append(twoThreeFive, s)
+		case 6:
+			zeroSixNine = append(zeroSixNine, s)
+		}
+	}
+
+	// Decode twoThreeFive
+	twoFive := []string{}
+	// Find 3 string
+	for s, v := range decoded {
+		if v == 1 {
+			for _, v := range twoThreeFive {
+				sharedSegments := 0
+				for _, segment := range s {
+					if strings.Contains(v, string(segment)) {
+						sharedSegments++
+					}
+				}
+				if sharedSegments == 2 {
+					decoded[v] = 3
+				} else {
+					twoFive = append(twoFive, v)
+				}
+			}
+		}
+	}
+	// Find 5 and 2 string
+	for s, v := range decoded {
+		if v == 4 {
+			for _, v := range twoFive {
+				sharedSegments := 0
+				for _, segment := range s {
+					if strings.Contains(v, string(segment)) {
+						sharedSegments++
+					}
+				}
+				if sharedSegments == 3 {
+					decoded[v] = 5
+				} else {
+					decoded[v] = 2
+				}
+			}
+		}
+	}
+
+	// Decode zeroSixNine
+	// Find 0 string
+	sixNine := []string{}
+	for s, v := range decoded {
+		if v == 5 {
+			for _, v := range zeroSixNine {
+				sharedSegments := 0
+				for _, segment := range s {
+					if strings.Contains(v, string(segment)) {
+						sharedSegments++
+					}
+				}
+				if sharedSegments != 5 {
+					decoded[v] = 0
+				} else {
+					sixNine = append(sixNine, v)
+				}
+			}
+		}
+	}
+
+	// Find the 9 and 6 strings
+	for s, v := range decoded {
+		if v == 1 {
+			for _, v := range sixNine {
+				sharedSegments := 0
+				for _, segment := range s {
+					if strings.Contains(v, string(segment)) {
+						sharedSegments++
+					}
+				}
+				if sharedSegments == 2 {
+					decoded[v] = 9
+				} else {
+					decoded[v] = 6
+				}
+			}
+		}
+	}
+
+	for i, signal := range o.outputs {
+		scale := 1
+		switch i {
+		case 0:
+			scale = 1000
+		case 1:
+			scale = 100
+		case 2:
+			scale = 10
+		}
+
+		segments := sort.StringSlice(strings.Split(signal, ""))
+		sort.Sort(segments)
+		sortedSignal := strings.Join(segments, "")
+
+		value += scale * decoded[sortedSignal]
+	}
+
+	return value
+}
+
+func (d *display) outputSum() (sum int) {
+	for _, o := range d.outputs {
+		sum += o.decode()
+	}
+	return sum
+}

eight/display_test.go

@@ -0,0 +1,58 @@
+package eight
+
+import "testing"
+
+func Test_read(t *testing.T) {
+	d := display{}
+	if err := d.load("test_input.txt"); err != nil {
+		t.Log(err)
+		t.FailNow()
+	}
+
+	if len(d.outputs) != 10 {
+		t.Logf("Expected 10 input sets, found %d", len(d.outputs))
+		t.Fail()
+	}
+
+	if len(d.outputs[0].signals) != 10 {
+		t.Logf("Expected 10 inputs, found %d", len(d.outputs[0].signals))
+		t.Fail()
+	}
+
+	if len(d.outputs[0].outputs) != 4 {
+		t.Logf("Expected 4 outputs, found %d", len(d.outputs[0].outputs))
+		t.Fail()
+	}
+}
+
+func Test_uniqueOutputs(t *testing.T) {
+	d := display{}
+	d.load("test_input.txt")
+
+	if count := d.uniqueOuputs(); count != 26 {
+		t.Logf("Expected 26 unique output digits, found %d", count)
+		t.Fail()
+	}
+}
+
+func Test_decode(t *testing.T) {
+	d := display{}
+	d.load("test_input.txt")
+
+	o := d.outputs[0]
+
+	if decoded := o.decode(); decoded != 8394 {
+		t.Logf("Expected output of 8394, decoded %d", decoded)
+		t.Fail()
+	}
+}
+
+func Test_outputSum(t *testing.T) {
+	d := display{}
+	d.load("test_input.txt")
+
+	if sum := d.outputSum(); sum != 61229 {
+		t.Logf("Expected outputs to sum to 61229, calculated %d", sum)
+		t.Fail()
+	}
+}

eight/input.txt

@@ -0,0 +1,200 @@
+dbc gfecab afcdg dfebcag bd dgbe bcaeg dcefab ecgadb agcbd | acdgb gbcda gdecfba bacge
+bacdegf aefbdc ebf fdbcag edbfa gdaeb acfdb cdegbf face fe | ebf ecdabf fcbad afcdbg
+cabgde gd becgfd dgfe cebgf gfdeacb fdbac bcgaef bgdfc gdc | cbfad dg dgef ecfbdg
+adecgf egfdc cgeadb adbfce dafg bcfeg dge dg fadec dcbegaf | dg dcegf cdgafe gbacfed
+badeg gdbfcea acgef fgdc bgcaef cd ebcfda gadce edcgaf edc | dce efcga dbgea dc
+bgfec dbfgec ebgafc afegcdb fca af cgdabf aegf badce cfabe | caf ebacf bafgec cbfeag
+begacd bd cfadbeg fbecg begfd bgd cdfeag gbaedf fdba agefd | cbgfe fdab efbdg bd
+bg gfdebc beg gabd fcbae fgaeb afegd gafdce dacbfge efgbda | gdba dfgae dgba gb
+cfd edcfbg abfcg gfdcb gbcefda dgcbe defg df acebfd caedbg | agedcbf dgbfaec gbfecd cdf
+bdcag acgebfd eac ae bade abcdgf bdacge bcgea aedgcf efcbg | cfdagb degacb eac edab
+ga ebcadgf gdaf bga fgecb dfabcg adcfb gadecb fecdab gbacf | fgda gdaf agb gfda
+gbcdaf fabdceg gbe ebfgad bfdga eg cefabg fdge adegb cedba | ge fcaedbg ebg aecbdfg
+ab bdeag gbdefc cgafdb fgedb agb befa bagfdec ecgda agfedb | ab aefb abg ab
+fgceab fcgdb fdcebg cbf gafbd cegfd bced cb cadfge cbdgafe | ecbagf cbfdeg cb bc
+fgb eafdgcb cefg ebdgac fcbged fbade fg gbfed gbecd fcabdg | fg eadfcgb fgcbda gedcb
+ecgfda faebc cb fadeb adecbg edfgabc bfgc cab gecaf ecbfag | fcgb bca gbcf cgbf
+gfaed cg cgab abdcf fabcgd gcfda fgc fdgacbe cbdaef fcebdg | fgc cfdageb cbfgad degfa
+fbacd gedfac fadegbc gbf degb ecgdf gb bdecfg gcdbf efbcag | cgedfb gb bcdfa cfdagbe
+dceg deacbg acfbeg egdafbc ebfda dc bcd cgabe gbdafc dbace | cged fabegc febad ebgcfa
+gbdcae cfgade dc dgbface fdage cbgfa adc gdafc dcfe gbdaef | fedc adgcf fcde dgacbfe
+afdgbe cgfabe dcgeab aef feacb fbgcade bgace cgef bcafd fe | ebacf abfdegc dbfac facgeb
+fbeg dgfecba cfgabd eafcb gb edacg gecfab aebcdf ebcag gcb | cfadeb gecda bg gb
+bfcaeg gd fbagc fgad fgcaedb fdgbac cdaeb dgfecb cagdb bdg | cbfgda dg afcedgb egfacb
+gd dcafgb dacfbe edbgacf gfbdc fbceg dbg dfag bdfca begdac | aecfdb eagdcfb fdcbgea fgdbc
+gf dfgc ebfgac bfdace gabfd adgfbc acbfd ecfagbd bgf aedgb | dfgc fdcg gfb gbf
+gbdae ebadf dbcfag acfdb dfec feacdbg geafcb dcbafe fe fae | efa bdcfa eaf debacgf
+deafgc fbgedca gfd dcga dcgbef aecfg dg agfebc adgfe dfabe | dgf badgcef fgace cabefgd
+badcg bagdce bdafgce efgbc df cbgfda cfdbg edgfac fgd adbf | dfcbg df cgbdae bdfgc
+dgabe beagc gbd gfcbdae gd bdegfa bgfedc fbcdae bafde fagd | bcdfge bgd bcage dfga
+adgf adgfce aecfg cdega dbgaecf abcgfe egd egcdfb dg deabc | cdgae dafg dfag afdg
+fbadec afcbg begac be ebcgda dceag edgb efdcga ebdacgf cbe | adfcebg ecafbd debgac edcafg
+cbd dcga cagbf dcafb cd cdebfg dgafcb baefd cbfaeg cfdgeab | fcdab geacbf gfbdce dgcafb
+becd abfdc cgbaf efcda bd ebdcaf gdfaceb bdf bdgeaf cedfga | ebdc fbd bdf fbgdae
+gefacd adcg fedbc cdgfe egd dg dbfega cgbfeda aecfg bcefga | defbcga efcga afgced gdecf
+gfacbd fbcgde cefba efdcga bfgcead egcdf gfb gcfbe bg edgb | gb fdegc gfb fgb
+ag agfdcb egfad fag adefb fdgec bdfgcae acfegd gebfdc aecg | fga ag egafd fcgebd
+cadgbf cd gefbac cdfba fbead cedagb gdcf adc gacbf fgebcda | gcbafd bdcaf gfcd abdfe
+fgebda fd afceb fcdeb fcad cgbed gabfcde dcabfe def befagc | eacfb efd efagcb def
+beaf gfcaebd fdeag dae acdgeb gcdfa dgabef gbedf ea dcbgef | ae aed ae ade
+gb dgeca gecab gcdfaeb ceafb bgc fagb adfceb baegcf gebfdc | fgba bg fecgab bg
+daf gbfda afcedg geadfb fbcdg fgaebc ad dbagefc dbae aebgf | aebd eadcbgf dfa beda
+dcbaef cabfd efgcba cbdgfa aedfg abecfdg ace cbde dfcae ce | cbefag ebcd cdabgf cbfda
+bcgefa bgfcead cd fcbadg bdcga dac gbaed gafdce cfbd bcagf | cbfag acd cfbd bdfc
+dgfcb aebgd gadefc bgfdec cbafgd cgbad egbdafc ac acbf cga | ca ac cabf abcf
+cgaed gafbdec fgaedc ba baegcd edfbg agcb bcdeaf ebdag bea | gfceda ecabfgd defgacb aeb
+cbfag cgdaf dcefab bac ba bdfceg cfgeb eagb cbfgea abcfdge | ba bac gabe cfbeda
+efcgd ecbafdg fgabed edb ebcg adcfb be efcdgb dfcgae dbefc | dcgef ebd becg gdfaebc
+fgedabc dafeb eg ged aegfbd afbecd fbgdc edfgb egaf dacegb | gaecdb cbegad fega fega
+bgfcdae fbcda df eafd gbcaed bdeca gfbac gfdbce bfadce bdf | afcbdeg gabfcde deaf cbeda
+fcgebda fcga bgfcd ebdfcg degba baf bafgd dfagbc bfcade af | afb agfc af cfegabd
+cbfg bfd eabfdg facbdg edfcgab bf fcabd aedcf ebgdac badcg | eafdc bdf bf fbcg
+fbdgce eagbfd dbacfeg dagb geabf cdeaf ebd bd fgbcae afebd | defac bed edb db
+aegcd bad gdaebcf cabfg db ecbd gafdce gcabd gbcade faebdg | dab dba dba cgfba
+ecdba bedacfg cdgeba dagcb bdge gdbfac fcadeg ced de acfeb | ed badfgc beacf bcgdafe
+fg abdeg fgebdca agdceb gfbd gdfae fga cdefa efagbc febgad | fg bgaefc gf bgafcde
+beadc gcbfed fdc bacf fc cbadefg feadc dgfea dcbefa dcgeba | cdf gefda dfc fbca
+bd bgcedf decafg gafcdb acgdf agbce bafd gaefbcd cdb acbdg | fcdga afbd cbfdeg cafdgb
+dabe bgcda egcdb fcdage dcebga bcfge dafgebc gdafcb ed ecd | ebad deba de gcbde
+ga gadcb ebcfdg egbcd agebdc eagb afcedg dbfca dfceagb dga | dabgc ga agd adbcg
+cbfagde ecdgf eabgfc fbd egbdf fageb edba dacbgf bdaegf bd | beda deab abgfe cegfd
+gcdfa gfea ef bdacfeg aedbc efc gfebdc adgbcf fecad aefcdg | feadc fe efc fgcad
+gdcae fga af acegfb fbda gfead edfgbc agdfecb dbgafe fdbge | fabd gfaed efgbd dagce
+afdebg febc cdbae abe eb dbfcea dabcfeg aecgdf dabgc dafce | cefb cedgaf eab acefd
+fgc dcabg gbdefac dfeg ecfdgb bfgcd gebcaf beafdc fg edbfc | cdfeb fcagbe fgbdace febdc
+aegfbd gacdeb fdeacgb dea dgcefb faeg bdfac dgefb ae debaf | debfg dea ea ead
+acgedb cfgae egfcbda fdeac eacbfd fd bdagfe dabec def fdcb | fed fd fcbd fde
+dba bgcfde da cdaf acfbgde fbgdc fgadeb dcbag agbec acgfdb | gacbdef adfgbe bgcad fcdabge
+acdfe cfgdab cdgea afgcebd dcgbae daf gfea fa egdfac bedfc | fa fad fa cedga
+caedg bafgde egcba dabegc agd fecdbga bcfeag fecdg ad abdc | gad cbeag dag cabd
+adfebg fedcagb fagdc gda eadc degcf gdafec ad cdbfge facbg | da aedc cbfgdea ad
+ecfdba dg dgafec gcabdfe fbadg fadcb gbdfca gfd bgefa dgbc | cgbd dbcaf cgdb dbgcfa
+ebacg eb begd dcebaf cdgea gafdce ecb cagfb bfadcge egcdba | bgdaecf bedacg dbeg cbdgae
+ebdagcf cgbea fe agefbc abgdf agfeb egafdc bcef feg deabcg | cegabd ecgafbd ef fe
+cd cgebdfa fgeabd cbd cabed gfbdec adcf abgce eafbd fcebad | efabcdg bcefgd baedc abfde
+acfg gbacfd edgfabc bdcaf dca caebdg dafbe gbcdf ac dfbgec | bgcfed cda dbgfc acd
+agdbefc abdc ecd gfcae aedbf gbcdef ebafdg ecadbf efadc cd | afdeb cde dbafce bfadge
+begad de fged gfbea dbe gbdac ebfgdac efgabd cadfbe fegabc | de dgfe cgfaeb gadbc
+gefdc gdfb gdbcaef deb ebfcd gcebad bd dacefg gdcbef fabce | gfedabc deb gcfade fdgb
+bdec dagcf cefbg bfgace bgedfc edacfbg fgdec fde adgefb de | dbfaegc cedb edfabcg fcdeg
+eaf gabed cabegdf fe ecbgaf fadeg gadfc fcdega cfde cbgafd | adgef fced cgdbafe fae
+fcbaedg gadce abcg ceb bgedf adfbec decagf bc dbceg eabdcg | ceb bgafecd cabg acefbd
+dagb cfgde acgfeb fbgac fcgdb bd dbf cbfagd fcbeda bcefgad | db fegdbca dbceafg aedbfc
+edagb da dab fbdge cgdfbe acegb adfe abdgfce dfgeab bfgcad | abd dab gfbead eagbc
+bdfega dcbgf efcgabd ce fec fcegd agce fegad daebfc efdcga | ec ecf dgacef bfecad
+cdabgef bgdfe aecgb gcfa fc acgebf dcaebf dcbgae cfgeb efc | fc fcga bfecga faecbdg
+dfeac gdfcea fcg acdebf cdge cgefa bdcgaf cg fegbdac bfage | cfg cfg gfeca fegac
+bfad bcf bedcga cadeb bf bceafd bcegfd dbaegfc ecfga cfbae | efacdb afbd bcf fb
+aegfcd bcdeg abcefg gcfea bcgafed bga afbe bagec ab fbdgac | gceba gacbe gbacef gab
+dca ebda bdfaceg acgdb gbcdea begcd efbdcg efacgd bfagc ad | adcbeg ad cbfga cfbgeda
+fadebc gcfbea becgf gf fgc abfg ecgbd dfecabg fcedag eafcb | ebfgc gaedfc bgcef gedabfc
+fadg eafgb gbead bdaec ecagbf dg gdb agfebd aedcgfb cfgbde | bfecdag bgd badce gd
+egcd efadb gacbfd bcaeg ecadgb adc bacegf adecb dc agedcfb | fcgabe degc acd cd
+bedfcag gc fagdec gfabce bfgec acgb befac gfc bgdef aecfbd | cg ebfdg cfg gc
+aegbdf gfabced fadebc gfde ed bcaeg fbgda eadbg fgbacd bde | dbcefag bed afcbged aegdb
+agd fagec cfbgda bfceagd fgeacb cdae gdbef dagef da efcdga | edbgf gda gedaf cdgfaeb
+fgaec eb fcgbd agfdeb cedb fabcdeg egb febcg dfbgec cdfgab | fgbcde dbeafg egcfdba gcbfd
+gfe fdbae ge bfgdc dgfaec cgeb dcfgbe dabfgc fdegb eabgcdf | gebc gceb defbcag afbcedg
+dfce cgbed fbcagd bcdgf ged bdfgae ed bdfceg agebc fabdegc | fcde gde gecdbf de
+dba dcafbg gcdefb fbged dgeab bfegad gaecd ba aebf egafdcb | beadg cfdbage bgafde acdge
+bcgdef cbdgeaf ae fbdace afbde gcdabe gdbfa edbcf fcea bea | dgafb adbfce ea fbdecga
+afdg fgebc fdeacbg fd gadcb fdcgb gfacbd gbeacd acdfeb dfc | fd bdcafeg caefbd dafg
+dfebag defa bdgfa beafg agbcfd eab cbagefd cfgbe ea acbgde | abdcge abe ae fecbg
+ef bgfdeac bdcefg cfdba ecf dgecba gfae abgefc ecbga acefb | debcag afge efag fe
+cg gbfc gabcd bgade dgc gbecafd egdfac dfbac abdcfe gabfdc | gcbad degfabc cgafbd adbgcf
+edbcgf acgbf fbaedc cbfae gfc agcdb dagecfb fg fcgbea eagf | fg adcbef fbeac fadcgeb
+deacg daeb dagbce ecdbgf edc ed bgaefc gecba dagcf abdgecf | cdaeg abcge dec ecd
+fcgadb caged bedc cdabeg dfaecbg befag db dgb eagbd gacdef | fecagdb begad dgb db
+fbcdga fgcad fecdg gcedab bfca adc ac bfdga dbfega eafbcdg | adc cbgade fgcadb ceabgd
+cefdbg gde bgfeac ed begcd cbefg bfde aedcgf cbafegd gacbd | fegbdac gcbefd cbgef bgedc
+bfdagc afdc bagcf gbfdc begcd begdaf beafgc dbefgac gfd fd | fcda df dfac dcbfg
+gcbfe bfeacg cedbf ge bfcga gfe gfecda ecbgdfa bgfadc bage | feg eagb gef abfgc
+bgfec bac abecdfg ab gdcea ebgcfa fagb aebcg caebfd gfcbed | ab ab cba acgbe
+gdbcf cbedg ce ceg abcgde adbeg efgcab bdfegac adec adfbeg | gaecdfb bedga cge cead
+eafcb cfdbe aeb acfeg ab dcgbfe adfb fgacedb ecabgd fdbcae | fbcde aedfcbg bea edcbf
+ebdca egc cgabe fbge cgbfda ge bacfg geacbf afdgec gebacfd | badce cge bgfcea ge
+gdfecb bdge gdf dgbcaf aefbgc bfecg fgdec dg ecdbfga deacf | dgf fedcagb gd gcedf
+agdeb cfdbag gcabd ed dacegbf gebfa eagbdc acde efcgbd edb | ed eagdb de de
+feag cfgbed feacbdg cfgade efcdg fcgdab afd dfeac af abedc | cbagfde dbagfc faeg dgabcf
+cdg efgbcd decgfa dcegb dgbf gd ebdcfga adebc gbcfe cefagb | bfecg dgbf gdbf dg
+gab dfceag gdcb bg gbead agdefbc gcabef acged efdba agdceb | gdcb bgdc edbfa bag
+bgafde afdgc gcafed efgdc ceda gdcebfa gdbacf de gbcef edg | edg gde eadfcbg cade
+gdb egcfadb gdef abcfd dg ebfag gadbef abdgf aefbgc cbgaed | fedgba dbegfac bfeagd gefcdba
+gad bdcag becdg gceabd dceafbg fgdeca fcgab ad baed dfcbge | cfaegdb gda ad gaedcfb
+dafbeg eadgbfc fgd bagcf gedb abdfce gafdb fcdgea gd efbda | gebd fdg gaefcd deagcf
+cdbe adefb ecfgbad bfcgad bacdf agcefd efd cdeafb aegfb de | gacebdf bdce fbcagd dcefab
+cb acdgbe bce cdegabf bgdefa aegdb cdbg acbde fcebga fdace | ebc abfdecg ceb gbacdfe
+cg fcedg edfbag ceag fdbec gdc faedcg bdcefag gbafcd dfeag | geca dgfacb cgd cg
+bcafde defac dcage dgfbce gafc cgaedf cgd cg fgcedab gdeab | cdg ebadg aedgcf fagc
+bdec dagbf ecagfb decbfa aefdc aeb dcegfa adefcbg ebadf be | cdbe gfadb eadfc dcbe
+bcgeda fc badfe gbfdaec fcge cfd bedfc cedbg adfgbc dcgebf | cf ebacgfd fgce fdbceag
+gd fgbdea dbg badce gdcab fcagedb fbacg beacfg cgfd dcafbg | fcdg gdcbfa dbg gdfc
+cag cdfa cgade edgcbf fcebga begfcad gfdcae egabd defgc ac | ca agc fgbace gac
+ecabf geacfb eabdcf dec cd bgecfda gfdbce edcba cdaf adgeb | ced aedfgbc dc gbeda
+fbdac ea cadefg fae beag facbe bfgeacd cfdegb bgfec gfecba | agbe ea bafce egbdcf
+bdc dbega abcdg gbcfa dc gcde cgbaefd cdfbae eagdbf ebgadc | adefcb agcfb cdb gced
+ceb ce debfca abgdfe bdaeg cabegd caeg dbgec dcbfg bdecgfa | ce abegd gdfcb fcbdgae
+cafedgb dgf bcfd cgdfbe acedfg gbfed agedb aecgfb bfgec fd | fdgbec feacdg df bgcfe
+ef abgfc cagfeb gdebfc fbae bcadfg defgabc feg gefac gceda | degac gfbac gabfc gfcea
+bfdeca bd eabfgc degbcfa cgdb gefbc dbf ecfbgd gaedf edgfb | dbfge bdf egbfca db
+fac cbdfg eacfbg gaecfdb bacfd bfeda acgd ac gbfecd cgfadb | dagc ac dcga bedfa
+egfbca aegcf gdcfab fdc adce fcedg cd cfgead fdebg cedagbf | dcgfe fdgbcea aedc cfebga
+da bfged afedcb gcebdf gefda fedbga edgbfca gdba eagfc eda | ead dcfebg defcgb efgbcd
+adefgb ecgf gcedb fedacb bec fbecdg cdfaebg gedfb gcbad ce | dcbfeag cfbged efgbad bcdfage
+dfec gcd agdbe bdafgc afcbge bgecfad bgcde bgfce bgedfc cd | fbecag beagdfc cgd cedf
+edbc agcfbe adefg cd defca gfabdc cad dgabefc dfebac bceaf | dbce ebdc febcdga cdgbefa
+ecdb eb acgebdf ebf dcfebg bgdefa fcgbd gcdbaf feacg cfebg | bef ecfbg egdcbfa cdgfb
+ebfcgd aefcb bfadge efd ed adfcgb fbgdc bfedagc fcebd dcge | gced fbcgd edgc ed
+beagf cefbag ebafc gfce gdfeab fcaedbg ec dfcba ecb gbadec | ce acfdb dbgcafe ec
+abegfc fbcged bgfea fecabdg gef ge abdgf gaec afecb cfbdea | cbfaedg bface gfe efabgc
+bdg bacd edagb fbegac fgaed bdgcae cgbea dfbegc ecgafdb bd | gdeaf cfdgbe gbcaed bd
+fbce fdegca egafb aef egdcfba eabgc fe ecdabg agfbd ecgbaf | fadgb cbage bcgdea abfgec
+dbafge fedgcab efgdbc bc fbac fbdea gceda bfceda bdcea ebc | eadcb fcdeab cafb bdecgf
+cbgae fec aefgcb acfeg fe efgcbd bgceafd fbea cagbed dcfga | edbagfc acefg gbdface ecf
+cbfdga bae ebdf fbadge afdgb gfeac acbdge bdacfeg eb agfeb | edbf bea efdcbag aeb
+efdcgab bedgaf aecbgf cgfe gfaeb cbgea ecbfad ec gdcab ecb | cgfe eabfg eabgf ec
+bdefa dfebgca bfe eadfcb dcbage bfgad debca cgebaf ef cdfe | gacdbe eagcfbd afcgebd dfgbace
+gca ebdcfa fdcgea acedb bdcgf eabg gbacde bcgdeaf ga gacdb | ebag abge gac aecdb
+abcgf afgcbe baeg gbc ecdbgf gafce facbd cfgade bg egabdfc | aegb cgb bcdgef abcgf
+ecagbf bdfgca ecgfd gbe fecgb dafgecb bacfg bgadec efba eb | geb cadfebg beaf be
+agcdb bgcaf bf fadebgc daecbf gbdf fbc ebgcda afegc bgcafd | facgdeb dbfg fb bf
+fdbeag cgd bdefcag afegd eacgdf dc dgefc ebcagd gfebc facd | geadf dc dc cdg
+adcgfe cgebf acdbf abcedf dgfbaec edba cabef ea afe dfagcb | bfgec bfeca ae deba
+adegb bgcd cbdfgea dc cedba cagefd dcbgae gebdaf faebc ced | egadb ced dcbg dc
+fdeg gd fdbaec bfacg dgcfa ecfdga fadcegb fdcea dceabg gda | efgd eacdfb bcfadeg dag
+af ebgfda ecagdb febgc afe dabce cfda febcda baecf becafdg | fa dbfega fa bfeagd
+debagfc cbdgfe dcb fdbeg cegb fbced fcead cbdfga bc fabdeg | dcb efadgb dgcfeab ebafdg
+cgfdae bdef becfg gcbefa ed abcdg gedcb cgbdef bdcgefa ecd | cde dec bfed bfcgdea
+dcfegab becdg gcaedb egd bcdaef gcfdb eg eafcdg cdeab ageb | ged cegafbd egd eg
+ba eafcd fcbegda acfgbd bedcgf ebgcfa fabdc dcgfb bagd baf | ba cafed efdbcag efdac
+aebcdgf cd efbgac bfcgd cbfga gbefd bfdcga bcad geafcd dgc | fabcged fgaceb cbda dc
+cgbaedf fbceg eafbcd degcf gfdcae gdcfa dbagcf dgae edf ed | fcgeb efd ed gdea
+ac agfdcbe gcea dgecf fgdca efgcad dfbeac fca fdgba gcebfd | agbdf ca ac gbdfa
+gbedaf dbgfc cbg abdfgc geadbc fecbd ebcgafd cafg gc dafbg | cdbfg gcfbad gcbdea fadcegb
+bagfec efg bfcdga egac abfecdg afdbge dbefc ge cgbfe acfbg | fbdeag eg eg cbdfe
+edbgcf dgbac bdceag dbagf cgd ecagb bceagf cd adce cgbafed | aecd egdbca gacbe gcd
+bgfdc gdfbe afdbgc gc fbdac bacg gbafdec cdg cbdefa defagc | egdfb gcabdef cdbfa dgacfb
+adgcfb gcd dfecgb cgebfa bgcaf adgcf cdbafeg dg ecafd adbg | bcgaf fadcgeb gd cgbaedf
+bafgd cfaebg cefa cfbgead bcf bgcea defgcb bgacf ebcgda cf | fcbgae adfbg cdfgeb adgbf
+becfa bcgdf gbceadf gebcfa defa adbcge de dec cebdf bdefac | faed fdcagbe edc bfacge
+ebfgd gabd gd gfbcaed abgfec faegb dge aefdbg agdfec cfebd | faecdg cgaedf baefgd dcfeb
+ecabd ged aebgfc ecagd dg fdcegb afgce dgaf dcaegf cedbgaf | edcga gfda gd dge
+dfg fg eafdb aegdc faged gfba debafg ebgfcad gfbdce acedbf | fedagb edbfac gf fgd
+dbgca fedca bfgcad adgcf agdecb dgf cefdgba bgaedf fcgb gf | acefdgb beafdg gfd cfbg
+edgacf adegcb fd dbacgfe fabd dfbce egcfb edfbac cbeda fde | dafb bafd acefbd fd
+bcefa gbfd eadcgb bgfdae gedcfa abefd efd df gedba fbdgeac | bfdae fgeacdb bacfe gdceba
+bdcefg aefgcd gadcb gfb decbfag dfecg bfdgc defb cefagb fb | defb fbcged dbfegac egfdc
+fe cedgab cbfe dacbfge cedba fed gafcd dfaec edbfac efdgab | abgedf efcb bedac gefbad
+afcgbe cf fbc cegadb bfcdea fcgabed aebdc adfgb cedf cfadb | dafbc bfeagc bcf deacbgf
+ebcafdg ecfbg bae dgcabf bcaedg dfbeca ae ebcag gdacb dage | cadbeg gbacd bfdegca eba
+cadbe efgbc feacbg dgfecb bgd dg bgfcad ebdgc dgef gbdefca | aefcgb gd bfagced dgb
+edgcfa dgbecfa bgedac dfbaec acgdf dg abfgc egdf adcef gdc | cgd cbgfa eacgdb gcafd
+cad cfbead abceg edfa fadbcg becad edgfcb bgfaedc cdbfe da | egcab afde dcabfe ecfabd
+fgbdc be egb bcdefag ceba gedbac egcda dcfgae debcg gbdaef | ceba edgac eadcfg bcdaeg
+cg adcfgbe edbcga gbead cbdfa cga bgedaf faecdg dbacg cebg | gcdabfe fdacge cga bcgad
+gacf gf bgeafd gef gefbc efbagc bdceag fdebc acfbedg gbaec | bcgaedf egf gcefb cafdegb
+fgbadce cdbag agcfd faec acfegd fa fag cfged fdabeg dbfcge | agf bagefd edgfc gdbacef
+agcdb gcadfb dgfcb gfdbec adebg adc ac cfab beagdcf daecfg | ac ca bedga ca
+dfa abdcfg agbf cfabd dacgb dcebf eadgcb fa gbdafce ecfgad | af fa bcdaf bgaf
+ebdfc cgbaed eg edabfc gefb adfgc gdfec deg ebdfgc debgcaf | abfcde bfge gde dge
+dabfegc dfegb cbgf cf fdebgc dcbaef gcfed adecg fbdgea fce | cf gbfc fgcb begcadf

eight/main.go

@@ -0,0 +1,26 @@
+package eight
+
+import "fmt"
+
+type Eight struct {
+	display display
+}
+
+func Init(filepath string) *Eight {
+	eight := &Eight{
+		display: display{},
+	}
+
+	eight.display.load(filepath)
+	return eight
+}
+
+func (d *Eight) Answer() string {
+	count := d.display.uniqueOuputs()
+	return fmt.Sprintf("There were %d instances of digits 1, 4, 7, or 8", count)
+}
+
+func (d *Eight) FollowUp() string {
+	outputSum := d.display.outputSum()
+	return fmt.Sprintf("The sum of the decoded output values was %d", outputSum)
+}

eight/test_input.txt

@@ -0,0 +1,10 @@
+be cfbegad cbdgef fgaecd cgeb fdcge agebfd fecdb fabcd edb | fdgacbe cefdb cefbgd gcbe
+edbfga begcd cbg gc gcadebf fbgde acbgfd abcde gfcbed gfec | fcgedb cgb dgebacf gc
+fgaebd cg bdaec gdafb agbcfd gdcbef bgcad gfac gcb cdgabef | cg cg fdcagb cbg
+fbegcd cbd adcefb dageb afcb bc aefdc ecdab fgdeca fcdbega | efabcd cedba gadfec cb
+aecbfdg fbg gf bafeg dbefa fcge gcbea fcaegb dgceab fcbdga | gecf egdcabf bgf bfgea
+fgeab ca afcebg bdacfeg cfaedg gcfdb baec bfadeg bafgc acf | gebdcfa ecba ca fadegcb
+dbcfg fgd bdegcaf fgec aegbdf ecdfab fbedc dacgb gdcebf gf | cefg dcbef fcge gbcadfe
+bdfegc cbegaf gecbf dfcage bdacg ed bedf ced adcbefg gebcd | ed bcgafe cdgba cbgef
+egadfb cdbfeg cegd fecab cgb gbdefca cg fgcdab egfdb bfceg | gbdfcae bgc cg cgb
+gcafb gcf dcaebfg ecagb gf abcdeg gaef cafbge fdbac fegbdc | fgae cfgab fg bagce

main.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"strings"
 
+	"unsupervised.ca/aoc2021/eight"
 	"unsupervised.ca/aoc2021/five"
 	"unsupervised.ca/aoc2021/four"
 	"unsupervised.ca/aoc2021/one"
@@ -43,6 +44,8 @@ func main() {
 		day = six.Init("six/input.txt")
 	case "seven":
 		day = seven.Init("seven/input.txt")
+	case "eight":
+		day = eight.Init("eight/input.txt")
 	default:
 		fmt.Printf("%q does not have a solution.\n", flagParts[1])
 		help()