feat: day 3

2024/3/3.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+func p1(data string) int {
+	mult, _ := matchMul(data)
+	sum := 0
+	for _, value := range mult {
+		sum += value
+	}
+	return sum
+}
+
+func p2(data string) int {
+	sum := 0
+	mulMult, mulIndexes := matchMul(data)
+
+	matchDos, _ := regexp.Compile(`do+\(\)`)
+	matchDonts, _ := regexp.Compile(`don't+\(\)`)
+	doIndex := matchDos.FindAllStringIndex(data, -1)
+	dontIndex := matchDonts.FindAllStringIndex(data, -1)
+	resolvedDos := sliceLast2dValue(doIndex)
+	resolvedDonts := sliceLast2dValue(dontIndex)
+	resolvedMul := sliceLast2dValue(mulIndexes)
+
+	for i, mulIndex := range resolvedMul {
+        lastControl := -1
+        lastWasDo := true
+
+        // find most recent control statement
+        for _, doIdx := range resolvedDos {
+            if doIdx < mulIndex && doIdx > lastControl {
+                lastControl = doIdx
+                lastWasDo = true
+            }
+        }
+        for _, dontIdx := range resolvedDonts {
+            if dontIdx < mulIndex && dontIdx > lastControl {
+                lastControl = dontIdx
+                lastWasDo = false
+            }
+        }
+
+        if lastWasDo {
+            sum += mulMult[i]
+        }
+	}
+
+	return sum
+}
+
+func main() {
+	data, err := os.ReadFile("input.txt")
+	if err != nil {
+		fmt.Println("File reading error", err)
+		return
+	}
+
+	fmt.Println("Part 1:", p1(string(data)))
+	fmt.Println("Part 2:", p2(string(data)))
+}
+
+func matchMul(data string) (mults []int, index [][]int) {
+	var multiplications []int
+	match, _ := regexp.Compile(`mul\(\d{1,3},\d{1,3}\)`)
+	resolved := match.FindAllString(data, -1)
+	resolvedIndex := match.FindAllStringIndex(data, -1)
+
+	numRegex, _ := regexp.Compile(`\d+,\d+`)
+	for _, resolves := range resolved {
+		num := strings.Split(numRegex.FindAllString(resolves, -1)[0], ",")
+		n0, _ := strconv.Atoi(num[0])
+		n1, _ := strconv.Atoi(num[1])
+		multiplications = append(multiplications, n0 * n1)
+	}
+	return multiplications, resolvedIndex
+}
+
+func sliceLast2dValue(array [][]int) []int {
+	var finalList []int
+	for _, value1 := range array {
+		finalList = append(finalList, value1[1])
+	}
+	return finalList
+}