Solve 2024 day 3 in go

2024/go/day-03/main.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"regexp"
+	"strconv"
+)
+
+func readInput() (string, error) {
+	content, err := os.ReadFile("input")
+	if err != nil {
+		return "", err
+	}
+
+	return string(content), nil
+}
+
+func instructionsResult(memory string) (int, int) {
+	regex := regexp.MustCompile(`mul\((\d{1,3}),(\d{1,3})\)|do\(\)|don't\(\)`)
+	matches := regex.FindAllStringSubmatch(memory, -1)
+	var totalSum, conditionalSum int
+
+	do := true
+	for _, match := range matches {
+		switch match[0] {
+		case "do()":
+			do = true
+		case "don't()":
+			do = false
+		default:
+			num1, _ := strconv.Atoi(match[1])
+			num2, _ := strconv.Atoi(match[2])
+
+			totalSum += num1 * num2
+			if do {
+				conditionalSum += num1 * num2
+			}
+		}
+	}
+
+	return totalSum, conditionalSum
+}
+
+func main() {
+	memory, err := readInput()
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	totalSum, conditionalSum := instructionsResult(memory)
+
+	// Part one
+	fmt.Println("Sum of the instructions:", totalSum)
+	// Part two
+	fmt.Println("Sum of the instructions but with conditionals:", conditionalSum)
+}