refactor: add common functions to internal package

It's time to add common functions to the internal 'common' package.

- Add the function that read the contents from a file to a list.
- Add the function that parses a list of integers from a string.

...and more to come later...

.forgejo/workflows/workflow.yaml

@@ -13,7 +13,7 @@ jobs:
     - name: Checkout Repository
       uses: https://code.forgejo.org/actions/checkout@v3
     - name: Setup Go
-      uses: https://code.forgejo.org/actions/setup-go@v3
+      uses: https://code.forgejo.org/actions/setup-go@v4
       with:
         go-version: '1.21'
     - name: Test

2023/day-1/README.asciidoc

@@ -1,69 +0,0 @@
-= Day 1: Trebuchet?!
-
-Original source: https://adventofcode.com/2023/day/1
-
-== Part One
-
-Something is wrong with global snow production, and you've been selected to take a look.
-The Elves have even given you a map; on it, they've used stars to mark the top fifty locations
-that are likely to be having problems.
-
-You've been doing this long enough to know that to restore snow operations,
-you need to check all **fifty stars** by 25th December 2023.
-
-Collect stars by solving puzzles.
-Two puzzles will be made available on each day in the Advent calendar;
-the second puzzle is unlocked when you complete the first.
-Each puzzle grants **one star**.
-Good luck!
-
-You try to ask why they can't just use a **weather machine** ("not powerful enough") and where they're
-even sending you ("the sky") and why your map looks mostly blank ("you sure ask a lot of questions")
-and hang on did you just say the sky ("of course, where do you think snow comes from") when you realize
-that the Elves are already loading you into a **trebuchet** ("please hold still, we need to strap you in").
-
-As they're making the final adjustments, they discover that their calibration document (your puzzle input)
-has been **amended** by a very young Elf who was apparently just excited to show off her art skills.
-Consequently, the Elves are having trouble reading the values on the document.
-
-The newly-improved calibration document consists of lines of text;
-each line originally contained a specific **calibration value** that the Elves now need to recover.
-On each line, the calibration value can be found by combining the **first digit** and the **last digit**
-(in that order) to form a single **two-digit number**.
-
-For example:
-
-----
-1abc2
-pqr3stu8vwx
-a1b2c3d4e5f
-treb7uchet
-----
-
-In this example, the calibration values of these four lines are
-`12`, `38`, `15`, and `77`. Adding these together produces `142`.
-
-Consider your entire calibration document. **What is the sum of all of the calibration values?**
-
-== Part Two
-
-Your calculation isn't quite right.
-It looks like some of the digits are actually spelled out with letters:
-`one`, `two`, `three`, `four`, `five`, `six`, `seven`, `eight`, and `nine` **also** count as valid "digits".
-
-Equipped with this new information, you now need to find the real first and last digit on each line. For example:
-
-----
-two1nine
-eightwothree
-abcone2threexyz
-xtwone3four
-4nineeightseven2
-zoneight234
-7pqrstsixteen
-----
-
-In this example, the calibration values are `29`, `83`, `13`, `24`, `42`, `14`, and `76`.
-Adding these together produces `281`.
-
-**What is the sum of all of the calibration values?**

2023/day-1/main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"codeflow.dananglin.me.uk/apollo/advent-of-code/internal/common"
+)
+
+func main() {
+	document, err := common.ReadFile("2023/day-1/files/input")
+	if err != nil {
+		log.Fatalf("Error: Unable to retrieve the calibration document; %v", err)
+	}
+
+	fmt.Printf("[Part 1] Total sum of calibration values: %d\n", partOneCalculateSumCalibrationValues(document))
+	fmt.Printf("[Part 2] Total sum of calibration values: %d\n", partTwoCalculateSumCalibrationValues(document))
+}

2023/day-1/main_test.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestDay1Trebuchet(t *testing.T) {
+	t.Logf("This is the test suite for Advent of Code - Day 1 - Trebuchet?!")
+	t.Run("Test the solution for Part 1", testPartOneCalculateSumCalibrationValues)
+	t.Run("Test the solution for Part 2", testPartTwoCalculateSumCalibrationValues)
+}
+
+func testPartOneCalculateSumCalibrationValues(t *testing.T) {
+	testStr := `
+1abc2
+pqr3stu8vwx
+a1b2c3d4e5f
+treb7uchet
+`
+
+	document := strings.Split(testStr, "\n")
+	got := partOneCalculateSumCalibrationValues(document)
+
+	want := 142
+
+	if want != got {
+		t.Errorf("Unexpected value returned from partOneCalculateSumCalibrationValues(); want %d, got %d", want, got)
+	}
+}
+
+func testPartTwoCalculateSumCalibrationValues(t *testing.T) {
+	testStr := `
+two1nine
+eightwothree
+abcone2threexyz
+xtwone3four
+4nineeightseven2
+zoneight234
+7pqrstsixteen
+`
+
+	document := strings.Split(testStr, "\n")
+	got := partTwoCalculateSumCalibrationValues(document)
+
+	want := 281
+
+	if want != got {
+		t.Errorf("Unexpected value returned from calculateSumCalibrationValues(); want %d, got %d", want, got)
+	}
+}

2023/day-1/part-1/main.go

@@ -1,49 +0,0 @@
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"io"
-	"log"
-	"os"
-)
-
-func main() {
-	file, err := os.Open("2023/day-1/files/input")
-	if err != nil {
-		log.Fatalf("Error: %v", err)
-	}
-	defer file.Close()
-
-	fmt.Printf("Sum total: %d\n", calculateSumCalibrationValues(file))
-
-}
-
-func calculateSumCalibrationValues(r io.Reader) int {
-	scanner := bufio.NewScanner(r)
-
-	sum := 0
-
-	for scanner.Scan() {
-		line := scanner.Text()
-		sum = sum + calibrationValue(line)
-	}
-
-	return sum
-}
-
-func calibrationValue(line string) int {
-	var digits []int
-
-	for _, r := range []rune(line) {
-		if (r >= '0') && (r <= '9') {
-			digits = append(digits, int(r-'0'))
-		}
-	}
-
-	if len(digits) == 0 {
-		return 0
-	}
-
-	return (10 * digits[0]) + digits[len(digits)-1]
-}

2023/day-1/part-1/main_test.go

@@ -1,24 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"testing"
-)
-
-func TestCalculateSumCalibrationValues(t *testing.T) {
-	testStr := `
-1abc2
-pqr3stu8vwx
-a1b2c3d4e5f
-treb7uchet
-`
-
-	buf := bytes.NewBuffer([]byte(testStr))
-
-	want := 142
-	got := calculateSumCalibrationValues(buf)
-
-	if want != got {
-		t.Errorf("Unexpected value returned from calculateSumCalibrationValues(); want %d, got %d", want, got)
-	}
-}

2023/day-1/part-2/main_test.go

@@ -1,27 +0,0 @@
-package main
-
-import (
-	"bytes"
-	"testing"
-)
-
-func TestCalculateSumCalibrationValues(t *testing.T) {
-	testStr := `
-two1nine
-eightwothree
-abcone2threexyz
-xtwone3four
-4nineeightseven2
-zoneight234
-7pqrstsixteen
-`
-
-	buf := bytes.NewBuffer([]byte(testStr))
-
-	want := 281
-	got := calculateSumCalibrationValues(buf)
-
-	if want != got {
-		t.Errorf("Unexpected value returned from calculateSumCalibrationValues(); want %d, got %d", want, got)
-	}
-}

2023/day-1/part_one.go

@@ -0,0 +1,27 @@
+package main
+
+func partOneCalculateSumCalibrationValues(document []string) int {
+	sum := 0
+
+	for _, line := range document {
+		sum = sum + calibrationValue(line)
+	}
+
+	return sum
+}
+
+func calibrationValue(line string) int {
+	var digits []int
+
+	for _, r := range []rune(line) {
+		if (r >= '0') && (r <= '9') {
+			digits = append(digits, int(r-'0'))
+		}
+	}
+
+	if len(digits) == 0 {
+		return 0
+	}
+
+	return (10 * digits[0]) + digits[len(digits)-1]
+}

2023/day-1/part_two.go

@@ -1,11 +1,6 @@
 package main
 
 import (
-	"bufio"
-	"fmt"
-	"io"
-	"log"
-	"os"
 	"strings"
 )
 
@@ -21,76 +16,62 @@ const (
 	nine  = "nine"
 )
 
-func main() {
+func partTwoCalculateSumCalibrationValues(document []string) int {
-	file, err := os.Open("2023/day-1/files/input")
+	sum := 0
-	if err != nil {
-		log.Fatalf("ERROR: %v\n", err)
-	}
-	defer file.Close()
 
-	fmt.Printf("Sum total: %d\n", calculateSumCalibrationValues(file))
+	for _, line := range document {
-}
+		sum = sum + partTwoCalibrationValue(line)
-
-func calculateSumCalibrationValues(r io.Reader) int {
-	scanner := bufio.NewScanner(r)
-
-	var (
-		digits []int
-		sum    int
-	)
-
-	for scanner.Scan() {
-		line := scanner.Text()
-		sum = sum + calibrationValue(line, digits)
 	}
 
 	return sum
 }
 
-func calibrationValue(line string, digits []int) int {
+func partTwoCalibrationValue(line string) int {
-	if len(line) > 0 {
+	var digits []int
+
+	for len(line) > 0 {
 		switch {
 		case (line[0] >= '0') && (line[0] <= '9'):
 			digits = append(digits, int(line[0]-'0'))
-			return calibrationValue(line[1:], digits)
+			line = line[1:]
 		case strings.HasPrefix(line, one):
 			digits = append(digits, 1)
 			trimLength := len(one) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, two):
 			digits = append(digits, 2)
 			trimLength := len(two) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, three):
 			digits = append(digits, 3)
 			trimLength := len(three) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, four):
 			digits = append(digits, 4)
 			trimLength := len(four) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, five):
 			digits = append(digits, 5)
 			trimLength := len(five) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, six):
 			digits = append(digits, 6)
 			trimLength := len(six) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, seven):
 			digits = append(digits, 7)
 			trimLength := len(seven) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, eight):
 			digits = append(digits, 8)
 			trimLength := len(eight) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		case strings.HasPrefix(line, nine):
 			digits = append(digits, 9)
 			trimLength := len(nine) - 1
-			return calibrationValue(line[trimLength:], digits)
+			line = line[trimLength:]
 		default:
-			return calibrationValue(line[1:], digits)
+			line = line[1:]
 		}
 	}
 

2023/day-2/game.go

@@ -80,7 +80,7 @@ func parseSets(str string) ([]Set, error) {
 					return nil, fmt.Errorf("unable to run strconv.Atoi() on %s; %w", i, err)
 				}
 				set.Green = value
-			case strings.HasSuffix(i, "blue"):
+			case strings.HasSuffix(i, blue):
 				value, err := strconv.Atoi(strings.TrimSuffix(i, blue))
 				if err != nil {
 					return nil, fmt.Errorf("unable to run strconv.Atoi() on %s; %w", i, err)

2023/day-2/game_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 )
 
-func TestParseGame(t *testing.T) {
+func testParseGame(t *testing.T) {
 	table := []struct {
 		testGame string
 		want     Game

2023/day-2/main.go

@@ -1,16 +1,16 @@
 package main
 
 import (
-	"bufio"
 	"fmt"
 	"log"
-	"os"
+
+	"codeflow.dananglin.me.uk/apollo/advent-of-code/internal/common"
 )
 
 func main() {
 	filename := "2023/day-2/files/input"
 
-	games, err := readFile(filename)
+	games, err := common.ReadFile(filename)
 	if err != nil {
 		log.Fatalf("ERROR: unable to read from %s, %v\n", filename, err)
 	}
@@ -115,21 +115,3 @@ func fewestSet(sets []Set) Set {
 
 	return result
 }
-
-func readFile(filename string) ([]string, error) {
-	file, err := os.Open(filename)
-	if err != nil {
-		return nil, fmt.Errorf("unable to open %s, %w", filename, err)
-	}
-
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	var content []string
-
-	for scanner.Scan() {
-		content = append(content, scanner.Text())
-	}
-
-	return content, nil
-}

2023/day-2/main_test.go

@@ -5,7 +5,10 @@ import (
 	"testing"
 )
 
-var testStr = `
+func TestDay2CubeConundrum(t *testing.T) {
+	t.Logf("This is the test suite for Advent of Code - Day 2 - Cube Conundrum")
+
+	testGames := `
 Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
 Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
 Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
@@ -13,32 +16,39 @@ Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
 Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
 `
 
-func TestSumOfGameIDs(t *testing.T) {
+	games := strings.Split(testGames, "\n")
-	games := strings.Split(testStr, "\n")
 
-	got, err := sumOfGameIDs(games)
+	t.Run("Test the game parsing functionality", testParseGame)
-	if err != nil {
+	t.Run("Test calculating the sum of Game IDs", testSumOfGameIDs(games))
-		t.Fatalf("Received an error after running sumOfGameIDs(); %v\n", err)
+	t.Run("Test calculating the sum of the Power of Cubes", testSumOfThePowerOfTheCubes(games))
-	}
+}
 
-	want := 8
+func testSumOfGameIDs(games []string) func(t *testing.T) {
+	return func(t *testing.T) {
+		got, err := sumOfGameIDs(games)
+		if err != nil {
+			t.Fatalf("Received an error after running sumOfGameIDs(); %v\n", err)
+		}
 
-	if got != want {
+		want := 8
-		t.Errorf("unexpected result received from sumOfGameIDs(); want %d, got %d\n", want, got)
+
+		if got != want {
+			t.Errorf("unexpected result received from sumOfGameIDs(); want %d, got %d\n", want, got)
+		}
 	}
 }
 
-func TestSumOfThePowerOfTheCubes(t *testing.T) {
+func testSumOfThePowerOfTheCubes(games []string) func(t *testing.T) {
-	games := strings.Split(testStr, "\n")
+	return func(t *testing.T) {
+		got, err := sumOfThePowerOfTheCubes(games)
+		if err != nil {
+			t.Fatalf("Received an error after running sumOfThePowerOfTheCubes(); %v\n", err)
+		}
 
-	got, err := sumOfThePowerOfTheCubes(games)
+		want := 2286
-	if err != nil {
-		t.Fatalf("Received an error after running sumOfThePowerOfTheCubes(); %v\n", err)
-	}
 
-	want := 2286
+		if got != want {
-
+			t.Errorf("unexpected result received from sumOfThePowerOfTheCubes(); want %d; got %d", want, got)
-	if got != want {
+		}
-		t.Errorf("unexpected result received from sumOfThePowerOfTheCubes(); want %d; got %d", want, got)
 	}
 }

2023/day-3/files/input

@@ -0,0 +1,140 @@
+..172..............................454..46.......507..........809......923.778..................793..............137.............238........
+............*.........712........=.......*................515.*...........*.......690.........../..........658.........=.........*..........
+.........823.835........%.........710.....749........134..%............................#812...&.....925.../..........276.......386..........
+519..................13......341.................481....=.....$............-.......211.......92.......*.....................................
+............832*105..@........$..................*.........797.....535..932.........*....152...........123.........678.540...........-...6..
+....&..948..........................271....-....228..79.26.........................733...=...715............27.586........*.......883...*...
+..172.......=..+.............88&....%....340.55.....+.............465..398......=..................585.......*....*812...347................
+...........374.462.......166..................*...........786........*....*910..675.................*.....149................653*....+80....
+.......*............680.....*......876.........864..................259.................124.169....799............608..*.........98......951
+....615.......*....%.....151.........*....#802........$.......680......................../...............857........-.901...............*...
+..............3.................637..493...........926....636..*.....350........881.........699......886.../.458...........#..474*409...246.
+...&...336......922............*..........370..............$..581....*.....335.*.......608$..*..11.......$....-..........928................
+...50..*.........*...........978...453.....*.......-..22..........298.......*...711.........794...*...267............44*.......460....*.....
+...................................*........534..797....-.............61....272.....@874..........892.....707.............230....*..72.537..
+....................405............309..........................221./..*....................872%.......75..*......237.....*.................
+..208.176..239.........*172.............795.............670.......*..9..504......*.717..641........908*....975.....*......130...............
+.....*....*.......711$....................*..54.....494..../.333.882...........282....@.......927*....../.......555..983*...........479.....
+.915......670.524................866...862..@.........*../....*...................................72.901..................995..........&....
+...*..%.......*.....71.............*..................33.350.796.....612.............#..463..............*399.....=.......*......309........
+....8..951.886......@......41*......606.680...787................605*.....892.......219.*........972..846.........377....644................
+..............................718........*.......*.......355*688............*.145...................*.......576.............................
+..........867.*.....................+...974...148..........................87.#........500&...534..986..269...*.....576....302....+.........
+........@......504.......-........652.........................104....@502......................*...............691.*.........*.423..706..402
+.286..218.882........-....579......................320.....=...-..........48.393.....202......758.....242..951..............................
+....*.....*.....$..943.............928.....*......*......310......&........*....*...*......=..............*......295*133....................
+..698...331...859.......91.........#....815....822..............39..........833....749...591...........455....*..........&30....*...........
+............*............+..............................117............................%........727........256.439...19.......478...........
+......67.595...599.........442...997..187.................@.596..276..141.597*792...780.........*......*.............@..............#.......
+266@.............-..713.....*....*.......=..783...564*.......*.......@.........................839......255.............636......749..%.....
+........+............*.....963.926.39../......&.......274...228..../.....812.........487@.24.............................*..*..........348..
+...618...364.936.....708...........*....63..&.......................212....-..191..............798................*....591..906.............
+......./.....@...............591...127.......491...141..*.....+...............*......339.@483........204*......871.465..................%...
+....890..................997*............723........$..675..465..............372.875*.........%..........534.............209.......*.....648
+..............+................139*..........273..................../7.....-..............854.920...968%..........384......%.......830......
+......+632...273.......132*........793.........................207..........952..../..66..*........................#...........@............
+.......................................162..................35.*.................22..*....234..........468...................#.750..........
+.....15...161.....................93....@...818..-580........*.449...................125...........129....*................723......365.....
+.....-....*.......678.........&21...=....../..............547.......$.........701....................#.....845.........................#....
+743........634...*.................................................679...........*176......979....................928.......$..848..........
+...............107....296....845.....*..........@...........................69..............$..442.........960/...........311.*.............
+.........................*............519.....58..............248.......582*........403.......*........929..............-......486.......151
+....-390....396.........279.......718............449.....794..#..............+......*......251...980....../.../...328..476..................
+.............*.....................-......../...*...........*...292.........188...&..112............*315.....529............................
+713..........860......114.743&.......368.776...195.........850.=................943............543...................483*625................
+......889........=.../.................*.............916.............201............-...............426&....627..............284............
+.452...........579...........786.961.15.......488.......*373.....830*......947.645.189........367.................$..../551.................
+....*.....99*........388.793...*...*....578..../...........................*...%.......-497.........@221..720...885.........588....692......
+....................*........903..81.......*.......*........=./....615.....202...355........997-..........*................$.........*......
+...........780.@....259.439.................483....596...490..415....*............-........................683........*371...&644..964......
+.......796......161.......*..#884....................................458.247.500........145.895.62.742.267..........16......................
+......+............../.998...........173..511............552*847...%.....&.........+651..*.....*........*.....108........+..............*975
+.444.....560.297...149..............*....*......*...................173...................365............986.$............271...182...26....
+....*84....*......................#..471.696.736.107....974...-614............................../...%930..........................+......364
+............800...-155..235......446...................*....................286.......822../...199............670-....................%.....
+....882.................*.................521....*20.282.............641.......*..703*.....887......513*271....................+819..100....
+.99..*........933*...649.......407............922...............-......*....681.............................*....#426...204.................
+.....112................../.....*...819.94......................689...652...........182.933.858.............711...............610.....*437..
+.540..........#.........740...500....*...$....184.......................................*....#.......386...........................668......
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+425....120.............*....401........................*....75..2..551.....*...719....................44..141...+..............+............
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2023/day-3/main.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"strconv"
+	"unicode"
+
+	"codeflow.dananglin.me.uk/apollo/advent-of-code/internal/common"
+)
+
+const (
+	dot           = '.'
+	potentialGear = '*'
+)
+
+type solution struct {
+	sumOfValidEnginePartNumbers int
+	sumOfGearRatios             int
+}
+
+func main() {
+	schematic, err := common.ReadFile("2023/day-3/files/input")
+	if err != nil {
+		log.Fatalf("ERROR: Unable to retrieve the engine schematic; %v\n", err)
+	}
+
+	answer, err := fixTheGondola(schematic)
+	if err != nil {
+		log.Fatalf("ERROR: Unable to calculate the sum of all valid engine part numbers; %v\n", err)
+	}
+
+	fmt.Printf("[Part 1] The sum of all valid engine part numbers: %d\n", answer.sumOfValidEnginePartNumbers)
+	fmt.Printf("[Part 2] The sum of all Gear Ratios: %d\n", answer.sumOfGearRatios)
+}
+
+func fixTheGondola(schematic []string) (solution, error) {
+	var (
+		partNumSum          = 0
+		partNum             = ""
+		validPartNum        = false
+		maxY                = len(schematic) - 1
+		maxX                = len(schematic[0]) - 1
+		mapOfPotentialGears = make(map[string][]int)
+		potentialGearPos    = ""
+	)
+
+	for y := range schematic {
+		for x, v := range schematic[y] {
+			if unicode.IsDigit(v) {
+				partNum = partNum + string(v)
+				if !validPartNum {
+					switch {
+					// check above left
+					case ((y - 1) >= 0) && ((x - 1) >= 0) && isSymbol(rune(schematic[y-1][x-1])):
+						validPartNum = true
+						if schematic[y-1][x-1] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y-1, x-1)
+						}
+					// check straight above
+					case ((y - 1) >= 0) && isSymbol(rune(schematic[y-1][x])):
+						validPartNum = true
+						if schematic[y-1][x] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y-1, x)
+						}
+					// check above right
+					case ((y - 1) >= 0) && ((x + 1) <= maxX) && isSymbol(rune(schematic[y-1][x+1])):
+						validPartNum = true
+						if schematic[y-1][x+1] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y-1, x+1)
+						}
+					// check left
+					case ((x - 1) >= 0) && isSymbol(rune(schematic[y][x-1])):
+						validPartNum = true
+						if schematic[y][x-1] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y, x-1)
+						}
+					// check right
+					case ((x + 1) <= maxX) && isSymbol(rune(schematic[y][x+1])):
+						validPartNum = true
+						if schematic[y][x+1] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y, x+1)
+						}
+					// check below left
+					case ((y + 1) <= maxY) && ((x - 1) >= 0) && isSymbol(rune(schematic[y+1][x-1])):
+						validPartNum = true
+						if schematic[y+1][x-1] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y+1, x-1)
+						}
+					// check straight below
+					case ((y + 1) <= maxY) && isSymbol(rune(schematic[y+1][x])):
+						validPartNum = true
+						if schematic[y+1][x] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y+1, x)
+						}
+					// check below right
+					case ((y + 1) <= maxY) && ((x + 1) <= maxX) && isSymbol(rune(schematic[y+1][x+1])):
+						validPartNum = true
+						if schematic[y+1][x+1] == potentialGear {
+							potentialGearPos = fmt.Sprintf("%d-%d", y+1, x+1)
+						}
+					}
+				}
+			} else {
+				if validPartNum {
+					value, err := strconv.Atoi(partNum)
+					if err != nil {
+						return solution{}, fmt.Errorf("unable to convert %q to int; %w", partNum, err)
+					}
+					partNumSum = partNumSum + value
+
+					if len(potentialGearPos) > 0 {
+						mapOfPotentialGears[potentialGearPos] = append(mapOfPotentialGears[potentialGearPos], value)
+					}
+				}
+
+				partNum = ""
+				validPartNum = false
+				potentialGearPos = ""
+			}
+		}
+	}
+
+	// Calculate the sum of all gear ratios
+	sumGearRatios := 0
+
+	for _, v := range mapOfPotentialGears {
+		if len(v) == 2 {
+			sumGearRatios = sumGearRatios + (v[0] * v[1])
+		}
+	}
+
+	answer := solution{
+		sumOfValidEnginePartNumbers: partNumSum,
+		sumOfGearRatios:             sumGearRatios,
+	}
+
+	return answer, nil
+}
+
+func isSymbol(r rune) bool {
+	return !unicode.IsDigit(r) && (r != dot)
+}

2023/day-3/main_test.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestDay3GearRatios(t *testing.T) {
+	t.Logf("This is the test suite for Advent of Code - Day 3 - Gear Ratio")
+
+	testEngineSchematic := `
+467..114..
+...*......
+..35..633.
+......#...
+617*......
+.....+.58.
+..592.....
+......755.
+...$.*....
+.664.598..
+`
+	schematic := strings.Split(testEngineSchematic, "\n")
+
+	// remove the first and last lines of the test schematic as they are blank.
+	schematic = schematic[1 : len(schematic)-1]
+
+	t.Run("Test the fix to the Gondola issue", testFixTheGondola(schematic))
+}
+
+func testFixTheGondola(schematic []string) func(t *testing.T) {
+	return func(t *testing.T) {
+		got, err := fixTheGondola(schematic)
+		if err != nil {
+			t.Fatalf("Received an error after running sumOfValidEnginePartNumbers(); %v\n", err)
+		}
+
+		want := solution{
+			sumOfValidEnginePartNumbers: 4361,
+			sumOfGearRatios:             467835,
+		}
+
+		if !reflect.DeepEqual(want, got) {
+			t.Errorf("unexpected result received from sumOfValidEnginePartNumbers(); want %d, got %d\n", want, got)
+		}
+	}
+}

2023/day-4/files/input

@@ -0,0 +1,192 @@
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2023/day-4/main.go

@@ -0,0 +1,151 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"strings"
+	"unicode"
+
+	"codeflow.dananglin.me.uk/apollo/advent-of-code/internal/common"
+)
+
+type cardResult struct {
+	numMatches int
+	cardScore  int
+}
+
+type solution struct {
+	sumUniqueScratchcardScores int
+	totalNumberOfScratchcards  int
+}
+
+func main() {
+	cards, err := common.ReadFile("2023/day-4/files/input")
+	if err != nil {
+		log.Fatalf("ERROR: Unable to retrieve the pack of scratchcards; %v\n", err)
+	}
+
+	answer, err := solveScratchCardWinnings(cards)
+	if err != nil {
+		log.Fatalf("ERROR: Unable to calculate the sum of all scratchcard points; %v\n", err)
+	}
+
+	fmt.Printf("[Part 1] The sum of all individual scratchcard scores: %d\n", answer.sumUniqueScratchcardScores)
+	fmt.Printf("[Part 2] The total number of scratchcards: %d\n", answer.totalNumberOfScratchcards)
+}
+
+func solveScratchCardWinnings(scratchcards []string) (solution, error) {
+	sumCardScores := 0
+	results := make([]cardResult, len(scratchcards))
+
+	var err error
+
+	// Calculate the total sum of the scores of each unique scratchcard.
+	for i, card := range scratchcards {
+		results[i], err = cardScore(card)
+		if err != nil {
+			return solution{}, fmt.Errorf("unable to calculate the card score for %q, %w", card, err)
+		}
+
+		sumCardScores = sumCardScores + results[i].cardScore
+	}
+
+	// Calculate the total number of unique and duplicated scratchcards.
+	cardCopies := make(map[int]int, len(scratchcards))
+	sumCardCopies := 0
+
+	for i := 0; i < len(scratchcards); i++ {
+		cardCopies[i] = 1
+	}
+
+	for i := 0; i < len(scratchcards); i++ {
+		for j := i + 1; j <= i+results[i].numMatches; j++ {
+			cardCopies[j] = cardCopies[j] + cardCopies[i]
+		}
+		sumCardCopies = sumCardCopies + cardCopies[i]
+	}
+
+	answer := solution{
+		sumUniqueScratchcardScores: sumCardScores,
+		totalNumberOfScratchcards:  sumCardCopies,
+	}
+
+	return answer, nil
+}
+
+func cardScore(card string) (cardResult, error) {
+	colonIndex := strings.Index(card, ":")
+	if colonIndex == -1 {
+		return cardResult{}, fmt.Errorf("unable to find the colon (:) in %q", card)
+	}
+
+	pipeIndex := strings.Index(card, "|")
+	if pipeIndex == -1 {
+		return cardResult{}, fmt.Errorf("unable to find the pipe (|) in %q", card)
+	}
+
+	winningNumbers := card[colonIndex+1 : pipeIndex]
+	playedNumbers := card[pipeIndex+1:]
+
+	// create a map of all winning numbers
+	winnningDigit := ""
+	cardMap := make(map[string]int)
+
+	for _, d := range winningNumbers {
+		if unicode.IsDigit(d) {
+			winnningDigit = winnningDigit + string(d)
+		} else {
+			if len(winnningDigit) > 0 {
+				cardMap[winnningDigit] = 0
+			}
+
+			winnningDigit = ""
+		}
+	}
+
+	// record the matching cards to the card map
+	playedDigit := ""
+
+	updateCardMap := func(digit string) {
+		if len(digit) > 0 {
+			if _, ok := cardMap[digit]; ok {
+				cardMap[digit] = cardMap[digit] + 1
+			}
+		}
+	}
+
+	for i, d := range playedNumbers {
+		if unicode.IsDigit(d) {
+			playedDigit = playedDigit + string(d)
+			if i == len(playedNumbers)-1 {
+				updateCardMap(playedDigit)
+			}
+		} else {
+			updateCardMap(playedDigit)
+			playedDigit = ""
+		}
+	}
+
+	// count the matches
+	matches := 0
+
+	for _, v := range cardMap {
+		if v == 1 {
+			matches++
+		}
+	}
+
+	// calculate the score
+	score := 0
+
+	if matches > 0 {
+		score = 1 << (matches - 1)
+	}
+
+	result := cardResult{
+		numMatches: matches,
+		cardScore:  score,
+	}
+
+	return result, nil
+}

2023/day-4/main_test.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestDay4Scratchcards(t *testing.T) {
+	t.Log("This is the test suite for Advent of Code - Day 4 - Scratchcards")
+
+	testScratchcard := `
+Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53
+Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
+Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1
+Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83
+Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
+Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11
+`
+
+	scratchcards := strings.Split(testScratchcard, "\n")
+
+	// remove the first and last lines of the test card pack as they are blank lines
+	scratchcards = scratchcards[1 : len(scratchcards)-1]
+
+	t.Run("Test the solution of the scratch card winnings", testSolveScratchCardWinnings(scratchcards))
+}
+
+func testSolveScratchCardWinnings(scratchcards []string) func(t *testing.T) {
+	return func(t *testing.T) {
+		got, err := solveScratchCardWinnings(scratchcards)
+		if err != nil {
+			t.Fatalf("Received an error after running solveScratchCardWinnings(); %v\n", err)
+		}
+
+		want := solution{
+			sumUniqueScratchcardScores: 13,
+			totalNumberOfScratchcards:  30,
+		}
+
+		if !reflect.DeepEqual(want, got) {
+			t.Errorf("unexpected result received from solveScratchCardWinnings(); want %d, got %d\n", want, got)
+		}
+	}
+}

README.asciidoc

@@ -1,8 +1,37 @@
 = Advent of Code
 
-My solutions to the https://adventofcode.com[Advent of Code] challenges.
+My solutions to the https://adventofcode.com[Advent of Code] challenges in Go.
 
 == Mirrors
 
 - **Code Flow (Forgejo)**: https://codeflow.dananglin.me.uk/apollo/advent-of-code
 - **GitHub**: https://github.com/dananglin/advent-of-code
+
+== How to run the solutions
+
+1. Download and install Go if you don't have it installed already.
+
+2. The provided bash script can be used to run the solution to an AoC challenge.
++
+....
+$ ./solve --help
+USAGE:
+  ./solve [options]
+
+SUMMARY:
+  Run the solution for the specified Advent of Code challenge
+
+OPTIONS:
+  -h, --help:
+    print this help message
+
+  -y, --year:
+    specify the year
+
+  -d, --day:
+    specify the day of the advent calendar
+....
+
+3. Run the script specifying the year and the day of the advent calendar to view the result of that day's challenge.
+
+    ./solve --year 2023 --day 1

internal/common/common.go

@@ -0,0 +1,65 @@
+package common
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"unicode"
+)
+
+func ReadFile(filename string) ([]string, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, fmt.Errorf("unable to open %q; %w", filename, err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	var lines []string
+
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("error scanning %q; %w", filename, err)
+	}
+
+	return lines, nil
+}
+
+func ParseIntList(line string) ([]int, error) {
+	var values []int
+	digitString := ""
+
+	addValue := func(digit string) error {
+		if len(digit) > 0 {
+			value, err := strconv.Atoi(digit)
+			if err != nil {
+				return fmt.Errorf("unable to parse %q to int; %w", digit, err)
+			}
+			values = append(values, value)
+		}
+
+		return nil
+	}
+
+	for i, v := range line {
+		if unicode.IsDigit(v) {
+			digitString = digitString + string(v)
+			if i == len(line)-1 {
+				if err := addValue(digitString); err != nil {
+					return nil, fmt.Errorf("unable to add %q to the list of ints; %w", digitString, err)
+				}
+			}
+		} else {
+			if err := addValue(digitString); err != nil {
+				return nil, fmt.Errorf("unable to add %q to the list of ints; %w", digitString, err)
+			}
+			digitString = ""
+		}
+	}
+
+	return values, nil
+}

internal/common/common_test.go

@@ -0,0 +1,33 @@
+package common
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestParseIntList(t *testing.T) {
+	table := []struct {
+		list string
+		want []int
+	}{
+		{
+			list: "87 2 435 89 100 1 0 16534",
+			want: []int{87, 2, 435, 89, 100, 1, 0, 16534},
+		},
+		{
+			list: "145, 834, 66, 2, 90, 123",
+			want: []int{145, 834, 66, 2, 90, 123},
+		},
+	}
+
+	for i := range table {
+		got, err := ParseIntList(table[i].list)
+		if err != nil {
+			t.Fatalf("received an error after running ParseIntList(); %v", err)
+		}
+
+		if !reflect.DeepEqual(got, table[i].want) {
+			t.Errorf("unexpected result received from ParseIntList(); want %v, got %v", table[i].want, got)
+		}
+	}
+}

solve

@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+function usage {
+    echo "USAGE:"
+    echo "  $0 [options]"
+    echo ""
+    echo "SUMMARY:"
+    echo "  Run the solution for the specified Advent of Code challenge"
+    echo ""
+    echo "OPTIONS:"
+    echo "  -h, --help:"
+    echo "    print this help message"
+    echo ""
+    echo "  -y, --year:"
+    echo "    specify the year"
+    echo ""
+    echo "  -d, --day:"
+    echo "    specify the day of the advent calendar"
+}
+
+while [[ $# -gt 0 ]]; do
+    arg="$1"
+    case $arg in
+        -h|--help)
+            usage
+            exit 0
+            ;;
+        -y|--year)
+            YEAR=$2
+            shift
+            shift
+            ;;
+        -d|--day)
+            DAY=$2
+            shift
+            shift
+            ;;
+        *)
+            shift
+            ;;
+    esac
+done
+
+if [[ -z "${YEAR+x}" ]]; then
+    echo "ERROR: please specify the year."
+    echo ""
+    usage
+    exit 1
+fi
+
+if [[ -z "${DAY+x}" ]]; then
+    echo "ERROR: please specify the day."
+    echo ""
+    usage
+    exit 1
+fi
+
+go run "./${YEAR}/day-${DAY}"