advent-of-code/2018/08/main.go

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package main
import (
"fmt"
"io/ioutil"
"strconv"
"strings"
)
type Node struct {
Metadata []int
Children []Node
}
func parseNode(input []int, start int) (parsed Node, end int) {
numChildren := input[start]
numMeta := input[start+1]
start += 2
for i := 0; i < numChildren; i++ {
var child Node
child, start = parseNode(input, start)
parsed.Children = append(parsed.Children, child)
}
for i := 0; i < numMeta; i++ {
parsed.Metadata = append(parsed.Metadata, input[start])
start++
}
return parsed, start
}
func metaSum(root Node) (sum int) {
for _, c := range root.Children {
sum += metaSum(c)
}
for _, m := range root.Metadata {
sum += m
}
return sum
}
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func specialSum(root Node) (sum int) {
if len(root.Children) == 0 {
return metaSum(root)
}
for _, m := range root.Metadata {
if m == 0 {
continue
}
if len(root.Children) >= m {
sum += specialSum(root.Children[m-1])
}
}
return sum
}
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func main() {
inFile, _ := ioutil.ReadFile("input")
rawInput := strings.Split(string(inFile), " ")
input := make([]int, len(rawInput))
for i, s := range rawInput {
input[i], _ = strconv.Atoi(s)
}
root, _ := parseNode(input, 0)
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// part 1
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fmt.Println(metaSum(root))
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// part 2
fmt.Println(specialSum(root))
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}