Day 03

2024/gareth/day03/day03.go

@@ -0,0 +1,49 @@
+package day03
+
+import (
+	"regexp"
+	"strconv"
+)
+
+func Part1(input string) int {
+	total := 0
+
+	regex := regexp.MustCompile(`mul\((\d+),(\d+)\)`)
+	matches := regex.FindAllStringSubmatch(input, -1)
+
+	for _, match := range matches {
+		if len(match) == 3 {
+			x, _ := strconv.Atoi(match[1])
+			y, _ := strconv.Atoi(match[2])
+			total += x * y
+		}
+	}
+	return total
+}
+
+func Part2(input string) int {
+	total := 0
+	isEnabled := true
+
+	mulRegex := regexp.MustCompile(`mul\((\d+),(\d+)\)`)
+	doRegex := regexp.MustCompile(`do\(\)`)
+	dontRegex := regexp.MustCompile(`don't\(\)`)
+
+	tokenizeRegex := regexp.MustCompile(`(mul\(\d+,\d+\)|do\(\)|don't\(\))`)
+	tokens := tokenizeRegex.FindAllString(input, -1)
+
+	for _, token := range tokens {
+		if doRegex.MatchString(token) {
+			isEnabled = true
+		} else if dontRegex.MatchString(token) {
+			isEnabled = false
+		} else if mulRegex.MatchString(token) && isEnabled {
+			mulMatch := mulRegex.FindStringSubmatch(token)
+			x, _ := strconv.Atoi(mulMatch[1])
+			y, _ := strconv.Atoi(mulMatch[2])
+			total += x * y
+		}
+	}
+
+	return total
+}