day 6

06/input.txt

@@ -0,0 +1 @@
+3,4,3,1,2

06/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"strconv"
+	"strings"
+)
+
+const (
+	MaxDays     = 256
+	PartOneDays = 80
+	MaxTimer    = 8
+)
+
+func shiftArrayLeft(arr *[MaxTimer + 1]int64) {
+	for i := 1; i < len(arr)-1; i++ {
+		arr[i-1] = arr[i]
+		arr[i] = arr[i+1]
+	}
+}
+
+func calcSum(arr *[MaxTimer + 1]int64) (sum int64) {
+	for _, v := range arr {
+		sum += v
+	}
+	return
+}
+
+func main() {
+	file, err := ioutil.ReadFile("input.txt")
+	if err != nil {
+		log.Fatal(err)
+	}
+	inputStrs := strings.Split(strings.Trim(string(file), "\n"), ",")
+
+	var dayCounts [MaxTimer + 1]int64
+	for _, v := range inputStrs {
+		num, _ := strconv.Atoi(v)
+		dayCounts[num]++
+	}
+
+	for daysPassed := 0; daysPassed < MaxDays; daysPassed++ {
+		if daysPassed == PartOneDays {
+			fmt.Println(calcSum(&dayCounts))
+		}
+
+		newSpawn := dayCounts[0]
+		shiftArrayLeft(&dayCounts)
+		dayCounts[6] += newSpawn
+		dayCounts[8] = newSpawn
+	}
+
+	fmt.Println(calcSum(&dayCounts))
+}