2024: day 11. part 2. golang

Author: Tsovak

src/2024/day11/2/data.txt

@@ -0,0 +1 @@
+4022724 951333 0 21633 5857 97 702 6

src/2024/day11/2/main.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	_ "embed"
+	"strconv"
+	"strings"
+)
+
+//go:embed data.txt
+var fileContents string
+
+func split(number uint64) []uint64 {
+	if number == 0 {
+		return []uint64{1}
+	}
+
+	numberStr := strconv.FormatUint(number, 10)
+	if len(numberStr)%2 == 0 {
+		half := len(numberStr) / 2
+		return []uint64{
+			mustParseUint(numberStr[:half]),
+			mustParseUint(numberStr[half:]),
+		}
+	}
+	return []uint64{number * 2024}
+}
+
+func mustParseUint(s string) uint64 {
+	num, err := strconv.ParseUint(s, 10, 64)
+	if err != nil {
+		panic(err)
+	}
+	return num
+}
+
+func blinking(numbers []uint64, until int) int {
+	stones := make(map[uint64]int)
+	for _, n := range numbers {
+		stones[n]++
+	}
+
+	for i := 0; i < until; i++ {
+		newStones := make(map[uint64]int)
+
+		for n, count := range stones {
+			splits := split(n)
+			for _, split := range splits {
+				newStones[split] += count
+			}
+		}
+
+		stones = newStones
+	}
+	total := 0
+	for _, count := range stones {
+		total += count
+	}
+	return total
+
+}
+
+func main() {
+	line := strings.TrimSpace(strings.Split(fileContents, "\n")[0])
+	numbers := make([]uint64, 0)
+	for _, numStr := range strings.Fields(line) {
+		num := mustParseUint(numStr)
+		numbers = append(numbers, num)
+	}
+
+	total := blinking(numbers, 75)
+	println(total)
+}