Added code for day 21

2024/cmd/root.go

@@ -29,6 +29,7 @@ import (
 	"cpatino.com/advent-of-code/2024/day18"
 	"cpatino.com/advent-of-code/2024/day19"
 	"cpatino.com/advent-of-code/2024/day20"
+	"cpatino.com/advent-of-code/2024/day21"
 )
 
 var days = map[int]func(string) (interface{}, interface{}){
@@ -52,6 +53,7 @@ var days = map[int]func(string) (interface{}, interface{}){
 	18: day18.Run,
 	19: day19.Run,
 	20: day20.Run,
+	21: day21.Run,
 }
 
 var rootCmd = &cobra.Command{

2024/day21/day21.go

@@ -0,0 +1,259 @@
+package day21
+
+import (
+	"bufio"
+	"image"
+	"math"
+	"os"
+	"regexp"
+	"strconv"
+)
+
+type Keypad interface {
+	GetButtonPosition(button rune) image.Point
+}
+
+type NumericKeypad struct {
+	ButtonPositions map[rune]image.Point
+}
+
+func (k *NumericKeypad) GetButtonPosition(button rune) image.Point {
+	return k.ButtonPositions[button]
+}
+
+type DirectionalKeypad struct {
+	ButtonPositions map[rune]image.Point
+}
+
+func (k *DirectionalKeypad) GetButtonPosition(button rune) image.Point {
+	return k.ButtonPositions[button]
+}
+
+var numeric = NumericKeypad{
+	ButtonPositions: map[rune]image.Point{
+		'A': image.Point{2, 0},
+		'0': image.Point{1, 0},
+		'1': image.Point{0, 1},
+		'2': image.Point{1, 1},
+		'3': image.Point{2, 1},
+		'4': image.Point{0, 2},
+		'5': image.Point{1, 2},
+		'6': image.Point{2, 2},
+		'7': image.Point{0, 3},
+		'8': image.Point{1, 3},
+		'9': image.Point{2, 3},
+	},
+}
+
+var directional = DirectionalKeypad{
+	ButtonPositions: map[rune]image.Point{
+		'A': image.Point{2, 1},
+		'^': image.Point{1, 1},
+		'<': image.Point{0, 0},
+		'v': image.Point{1, 0},
+		'>': image.Point{2, 0},
+	},
+}
+
+func getDirectional(input string, start rune) string {
+	curr := directional.GetButtonPosition(start)
+	seq := []rune{}
+
+	for _, char := range input {
+		dest := directional.GetButtonPosition(char)
+		dx, dy := dest.X-curr.X, dest.Y-curr.Y
+
+		horiz, vert := []rune{}, []rune{}
+
+		for i := 0; i < int(math.Abs(float64(dx))); i++ {
+			if dx >= 0 {
+				horiz = append(horiz, '>')
+			} else {
+				horiz = append(horiz, '<')
+			}
+		}
+
+		for i := 0; i < int(math.Abs(float64(dy))); i++ {
+			if dy >= 0 {
+				vert = append(vert, '^')
+			} else {
+				vert = append(vert, 'v')
+			}
+		}
+
+		if curr.X == 0 && dest.Y == 1 {
+			seq = append(seq, horiz...)
+			seq = append(seq, vert...)
+		} else if curr.Y == 1 && dest.X == 0 {
+			seq = append(seq, vert...)
+			seq = append(seq, horiz...)
+		} else if dx < 0 {
+			seq = append(seq, horiz...)
+			seq = append(seq, vert...)
+		} else {
+			seq = append(seq, vert...)
+			seq = append(seq, horiz...)
+		}
+
+		curr = dest
+		seq = append(seq, 'A')
+	}
+
+	return string(seq)
+}
+
+func getNumeric(input string, start rune) string {
+	curr := numeric.GetButtonPosition(start)
+	seq := []rune{}
+
+	for _, char := range input {
+		dest := numeric.GetButtonPosition(char)
+		dx, dy := dest.X-curr.X, dest.Y-curr.Y
+
+		horiz, vert := []rune{}, []rune{}
+		for i := 0; i < int(math.Abs(float64(dx))); i++ {
+			if dx >= 0 {
+				horiz = append(horiz, '>')
+			} else {
+				horiz = append(horiz, '<')
+			}
+		}
+		for i := 0; i < int(math.Abs(float64(dy))); i++ {
+			if dy >= 0 {
+				vert = append(vert, '^')
+			} else {
+				vert = append(vert, 'v')
+			}
+		}
+
+		if curr.Y == 0 && dest.X == 0 {
+			seq = append(seq, vert...)
+			seq = append(seq, horiz...)
+		} else if curr.X == 0 && dest.Y == 0 {
+			seq = append(seq, horiz...)
+			seq = append(seq, vert...)
+		} else if dx < 0 {
+			seq = append(seq, horiz...)
+			seq = append(seq, vert...)
+		} else {
+			seq = append(seq, vert...)
+			seq = append(seq, horiz...)
+		}
+
+		curr = dest
+		seq = append(seq, 'A')
+	}
+
+	return string(seq)
+}
+
+func split(input string) []string {
+	var result []string
+	var current string
+
+	for _, char := range input {
+		current += string(char)
+		if char == 'A' {
+			result = append(result, current)
+			current = ""
+		}
+	}
+
+	return result
+}
+
+func count(input string, maxRobots, robot int) int {
+	if val, ok := cache[input]; ok && robot <= len(val) && val[robot-1] != 0 {
+		return val[robot-1]
+	}
+
+	seq := getDirectional(input, 'A')
+	if robot == maxRobots {
+		return len(seq)
+	}
+
+	if _, ok := cache[input]; !ok {
+		cache[input] = make([]int, maxRobots)
+	}
+
+	steps := split(seq)
+	total := 0
+	for _, step := range steps {
+		c := count(step, maxRobots, robot+1)
+		total += c
+	}
+
+	cache[input][robot-1] = total
+	return total
+}
+
+var cache map[string][]int
+
+func Part1(sequences []string) int {
+	cache = make(map[string][]int)
+	re := regexp.MustCompile(`\d+`)
+
+	complexity := 0
+	for _, sequence := range sequences {
+		numericCode := re.FindString(sequence)
+		value, err := strconv.Atoi(numericCode)
+		if err != nil {
+			panic(err)
+		}
+
+		moves := getNumeric(sequence, 'A')
+		length := count(moves, 2, 1)
+
+		complexity += length * value
+	}
+
+	return complexity
+}
+
+func Part2(sequences []string) int {
+	cache = make(map[string][]int)
+	re := regexp.MustCompile(`\d+`)
+
+	complexity := 0
+	for _, sequence := range sequences {
+		numericCode := re.FindString(sequence)
+		value, err := strconv.Atoi(numericCode)
+		if err != nil {
+			panic(err)
+		}
+
+		moves := getNumeric(sequence, 'A')
+		length := count(moves, 25, 1)
+
+		complexity += length * value
+	}
+
+	return complexity
+}
+
+func Run(filename string) (interface{}, interface{}) {
+	file, err := os.Open(filename)
+	if err != nil {
+		panic(err)
+	}
+	defer file.Close()
+
+	var sequences []string
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		if scanner.Text() == "" {
+			break
+		}
+		sequences = append(sequences, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+
+	part1 := Part1(sequences)
+	part2 := Part2(sequences)
+
+	return part1, part2
+}

2024/day21/day21_test.go

@@ -0,0 +1,34 @@
+package day21
+
+import (
+	"os"
+	"testing"
+)
+
+type TestCase struct {
+	FileName string
+	Part1    interface{}
+	Part2    interface{}
+}
+
+func TestDay21(t *testing.T) {
+	tests := []TestCase{
+		{"test.txt", 126384, 154115708116294},
+		{"input.txt", 176452, 218309335714068},
+	}
+
+	for _, test := range tests {
+		if _, err := os.Stat(test.FileName); os.IsNotExist(err) {
+			t.Fatalf("test file does not exist: %v", test.FileName)
+		}
+
+		part1, part2 := Run(test.FileName)
+		if test.Part1 != nil && part1 != test.Part1 {
+			t.Fatalf("%s: unexpected part1:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part1, part1)
+		}
+
+		if test.Part2 != nil && part2 != test.Part2 {
+			t.Fatalf("%s: unexpected part2:\nwant:\t%v\ngot:\t%v", test.FileName, test.Part2, part2)
+		}
+	}
+}

2024/day21/input.txt

@@ -0,0 +1,5 @@
+480A
+682A
+140A
+246A
+938A

2024/day21/test.txt

@@ -0,0 +1,5 @@
+029A
+980A
+179A
+456A
+379A