[2024] Solution for Day 3

Author: kfarnung

2024/day01/main_test.go

@@ -15,6 +15,7 @@ var input = strings.Join([]string{
 	"1   3",
 	"3   9",
 	"3   3",
+	"",
 }, "\n")
 
 func TestPart1(t *testing.T) {

2024/day02/main_test.go

@@ -15,6 +15,7 @@ var input = strings.Join([]string{
 	"1 3 2 4 5",
 	"8 6 4 4 1",
 	"1 3 6 7 9",
+	"",
 }, "\n")
 
 func TestPart1(t *testing.T) {

2024/day03/main.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"regexp"
+
+	"github.com/kfarnung/advent-of-code/2024/lib"
+)
+
+var mulRegex = regexp.MustCompile(`mul\((\d+),(\d+)\)|do\(\)|don't\(\)`)
+
+func part1(input string) int64 {
+	matches := mulRegex.FindAllStringSubmatch(input, -1)
+
+	sum := int64(0)
+	for _, match := range matches {
+		if match[0] == "do()" || match[0] == "don't()" {
+			continue
+		}
+
+		first, err := lib.ParseInt[int64](match[1])
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		second, err := lib.ParseInt[int64](match[2])
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		sum += first * second
+	}
+
+	return sum
+}
+
+func part2(input string) int64 {
+	matches := mulRegex.FindAllStringSubmatch(input, -1)
+
+	enabled := true
+	sum := int64(0)
+	for _, match := range matches {
+		if match[0] == "do()" {
+			enabled = true
+		} else if match[0] == "don't()" {
+			enabled = false
+		} else if enabled {
+
+			first, err := lib.ParseInt[int64](match[1])
+			if err != nil {
+				log.Fatal(err)
+			}
+
+			second, err := lib.ParseInt[int64](match[2])
+			if err != nil {
+				log.Fatal(err)
+			}
+
+			sum += first * second
+		}
+	}
+
+	return sum
+}
+
+func main() {
+	name := os.Args[1]
+	content, err := lib.LoadFileContent(name)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Part 1: %d\n", part1(content))
+	fmt.Printf("Part 2: %d\n", part2(content))
+}

2024/day03/main_test.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/kfarnung/advent-of-code/2024/lib"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPart1(t *testing.T) {
+	input := strings.Join([]string{
+		"xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))",
+		"",
+	}, "\n")
+	assert.Equal(t, int64(161), part1(input))
+
+	inputContent, err := lib.GetInputContent()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	assert.Equal(t, int64(187833789), part1(inputContent))
+}
+
+func TestPart2(t *testing.T) {
+	input := strings.Join([]string{
+		"xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))",
+		"",
+	}, "\n")
+	assert.Equal(t, int64(48), part2(input))
+
+	inputContent, err := lib.GetInputContent()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	assert.Equal(t, int64(94455185), part2(inputContent))
+}