Day 8 part 1 solution.

2018/day08-1.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+
+	"internal/day08"
+	"internal/util"
+)
+
+func main() {
+	data := util.ReadInputInts()
+	root := day08.BuildTree(data)
+	fmt.Println(sumMetadata(root))
+}
+
+func sumMetadata(node *day08.Node) int {
+	sum := 0
+	for _, v := range node.Metadata {
+		sum += v
+	}
+
+	for _, child := range node.Children {
+		sum += sumMetadata(child)
+	}
+
+	return sum
+}

2018/internal/day08/debug.go

@@ -0,0 +1,25 @@
+package day08
+
+import (
+	"fmt"
+)
+
+func DebugPrintTree(root *Node) {
+	debugPrintTreeR(root, 0)
+}
+
+func debugPrintTreeR(node *Node, indent int) {
+	for i := 0; i < indent; i++ {
+		fmt.Printf(" ")
+	}
+	fmt.Printf("Children: %d | Metadata: ", len(node.Children))
+
+	for _, md := range node.Metadata {
+		fmt.Printf("%d ", md)
+	}
+	fmt.Println()
+
+	for _, child := range node.Children {
+		debugPrintTreeR(child, indent+1)
+	}
+}

2018/internal/day08/tree.go

@@ -0,0 +1,30 @@
+package day08
+
+type Node struct {
+	Children []*Node
+	Metadata []int
+}
+
+func BuildTree(data []int) *Node {
+	root, _ := buildTreeR(data, 0)
+	return root
+}
+
+func buildTreeR(data []int, index int) (*Node, int) {
+	node := &Node{}
+	numChildren := data[index]
+	numMetadata := data[index+1]
+	index += 2
+
+	for i := 0; i < numChildren; i++ {
+		var child *Node
+		child, index = buildTreeR(data, index)
+		node.Children = append(node.Children, child)
+	}
+
+	for i := 0; i < numMetadata; i++ {
+		node.Metadata = append(node.Metadata, data[index+i])
+	}
+
+	return node, index + numMetadata
+}

2018/internal/util/input.go

@@ -5,6 +5,8 @@ import (
 	"bytes"
 	"io/ioutil"
 	"os"
+	"strconv"
+	"strings"
 )
 
 // ReadInput isn't here to make friends. It is highly specific to this domain.
@@ -25,7 +27,7 @@ func ReadInput() []string {
 	return lines
 }
 
-// ReadInputS is like ReadInput, but returns a byte array.
+// ReadInputBytes is like ReadInput, but returns a byte array.
 func ReadInputBytes() []byte {
 	rawData, err := ioutil.ReadFile(os.Args[1])
 
@@ -35,3 +37,26 @@ func ReadInputBytes() []byte {
 
 	return bytes.TrimRight(rawData, "\n")
 }
+
+// ReadInputInts is like ReadInput, but returns an array of ints. (space-separated in the input)
+func ReadInputInts() []int {
+	rawData, err := ioutil.ReadFile(os.Args[1])
+
+	if err != nil {
+		panic(err)
+	}
+
+	strData := strings.Split(strings.TrimSpace(string(rawData)), " ")
+	data := []int{}
+	for _, newIntStr := range strData {
+		newInt, err := strconv.Atoi(newIntStr)
+
+		if err != nil {
+			panic(err)
+		}
+
+		data = append(data, newInt)
+	}
+
+	return data
+}