advent2022

commit 1fd84fa16914c0d363e9c86eb3c63c368b3e957b
parent 25b8bbe6203fa094f3e803a69779e4f87db9d6a3
Author: bsandro <email@bsandro.tech>
Date:   Sat,  3 Dec 2022 06:40:09 +0000

Day 03 part 2

Diffstat:
M
day03/main.go
 | 
58
+++++++++++++++++++++++++++++++++++++++++++---------------

1 file changed, 43 insertions(+), 15 deletions(-)
diff --git a/day03/main.go b/day03/main.go
@@ -25,33 +25,45 @@ func day03(input_file string) {
 	}
 	defer input.Close()
 	scanner := bufio.NewScanner(input)
-	var sum int32 = 0
+	var sum1 int32 = 0
+	var sum2 int32 = 0
+	var group []string
 	for scanner.Scan() {
-		same := findSame(scanner.Text())
-		// unicode rune to fantasy scoring
-		if same >= 97 { // lowercase
-			same -= 96
-		} else if same >= 65 { // uppercase
-			same -= 38
-		} else {
-			log.Fatal("Invalid rune")
+		rucksack := scanner.Text()
+		item1 := compareCompartments(rucksack)
+		sum1 += getItemScore(item1)
+		group = append(group, rucksack)
+		if len(group) == 3 {
+			item2 := compareRucksacks(group)
+			sum2 += getItemScore(item2)
+			group = nil
 		}
-		fmt.Printf("%v\n", same)
-		sum += same
 	}
-	fmt.Println("Part 1:", sum)
 	if err = scanner.Err(); err != nil {
 		log.Fatal(err)
 	}
+
+	fmt.Println("Part 1:", sum1)
+	fmt.Println("Part 2:", sum2)
+}
+
+func getItemScore(item int32) int32 {
+	// unicode rune to fantasy scoring
+	if item >= 97 { // lowercase
+		return item - 96
+	} else if item >= 65 { // uppercase
+		return item - 38
+	}
+	return 0
 }
 
-func findSame(in string) int32 {
+func compareCompartments(in string) int32 {
 	strLen := len(in)
-	if strLen % 2 != 0 {
+	if strLen%2 != 0 {
 		log.Fatal("invalid input string")
 	}
 
-	comp1 := in[0:strLen/2]
+	comp1 := in[0 : strLen/2]
 	comp2 := in[strLen/2:]
 
 	// only 1 misplaced item per rucksack
@@ -65,3 +77,19 @@ func findSame(in string) int32 {
 
 	return 0
 }
+
+func compareRucksacks(group []string) int32 {
+	if len(group) != 3 {
+		log.Fatal("Group size has to be 3")
+	}
+	for _, r1 := range group[0] {
+		for _, r2 := range group[1] {
+			for _, r3 := range group[2] {
+				if r1 == r2 && r2 == r3 {
+					return r1
+				}
+			}
+		}
+	}
+	return 0
+}