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| 1 | +package main |
| 2 | + |
| 3 | +import ( |
| 4 | + "fmt" |
| 5 | + "os" |
| 6 | + "strconv" |
| 7 | + "strings" |
| 8 | +) |
| 9 | + |
| 10 | +type Node struct { |
| 11 | + id int |
| 12 | + children []*Node |
| 13 | + metadata []int |
| 14 | + value int |
| 15 | +} |
| 16 | + |
| 17 | +func main() { |
| 18 | + f, _ := os.ReadFile("input.txt") |
| 19 | + numbers := toInt(strings.Fields(strings.TrimSpace(string(f)))) |
| 20 | + root := Node{0, []*Node{}, []int{}, 0} |
| 21 | + createTree(&root, 0, 0, numbers) |
| 22 | + // printTree(&root) // Debug purposes. |
| 23 | + fmt.Printf("Part 1 | Sum of the metadata: %d\n", addMetadata(&root)) |
| 24 | + fmt.Printf("Part 2 | Value of the root node: %d\n", addMetadataWithChildren(&root)) |
| 25 | +} |
| 26 | + |
| 27 | +func addMetadata(root *Node) int { |
| 28 | + s := 0 |
| 29 | + if root != nil { |
| 30 | + s += root.value |
| 31 | + for _, children := range root.children { |
| 32 | + s += addMetadata(children) |
| 33 | + } |
| 34 | + } |
| 35 | + return s |
| 36 | +} |
| 37 | + |
| 38 | +func addMetadataWithChildren(root *Node) int { |
| 39 | + s := 0 |
| 40 | + if root != nil { |
| 41 | + if len(root.children) > 0 { |
| 42 | + for _, childNumber := range root.metadata { |
| 43 | + if childNumber >= 1 && childNumber <= len(root.children) { |
| 44 | + s += addMetadataWithChildren(root.children[childNumber-1]) |
| 45 | + } |
| 46 | + } |
| 47 | + } else { |
| 48 | + s = root.value |
| 49 | + } |
| 50 | + } |
| 51 | + return s |
| 52 | +} |
| 53 | + |
| 54 | +func createTree(root *Node, index int, id int, numbers []int) (*Node, int) { |
| 55 | + if index >= len(numbers) { |
| 56 | + return nil, 0 |
| 57 | + } |
| 58 | + root.id = id |
| 59 | + children := numbers[index] |
| 60 | + metadata := numbers[index+1] |
| 61 | + index += 2 |
| 62 | + // Index will always point to the number of children. |
| 63 | + for i := range children { |
| 64 | + child, j := createTree(&Node{}, index, id+1+i, numbers) |
| 65 | + root.children = append(root.children, child) |
| 66 | + index = j |
| 67 | + } |
| 68 | + sum := 0 |
| 69 | + for range metadata { |
| 70 | + sum += numbers[index] |
| 71 | + root.metadata = append(root.metadata, numbers[index]) |
| 72 | + index++ |
| 73 | + } |
| 74 | + root.value = sum // This helps in readability to sum the metadata. |
| 75 | + return root, index |
| 76 | +} |
| 77 | + |
| 78 | +func printTree(root *Node) { |
| 79 | + if root != nil { |
| 80 | + fmt.Printf("Node: +%v\n", root) |
| 81 | + for _, node := range root.children { |
| 82 | + printTree(node) |
| 83 | + } |
| 84 | + } |
| 85 | +} |
| 86 | + |
| 87 | +func toInt(numbers []string) []int { |
| 88 | + n := make([]int, len(numbers)) |
| 89 | + for i, number := range numbers { |
| 90 | + val, _ := strconv.Atoi(number) |
| 91 | + n[i] = val |
| 92 | + } |
| 93 | + return n |
| 94 | +} |
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