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@@ -0,0 +1,92 @@
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+package main
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+
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+import (
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+ "bufio"
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+ "fmt"
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+ "log"
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+ "os"
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+ "strings"
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+)
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+
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+type kind byte
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+
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+const (
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+ op kind = iota
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+ val
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+)
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+
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+type monkey struct {
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+ name string
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+ spec kind
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+ left string
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+ right string
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+ op byte
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+ value int
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+}
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+
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+func readInput(file *os.File) map[string]monkey {
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+ scanner := bufio.NewScanner(file)
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+ monkeys := make(map[string]monkey)
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+
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+ for scanner.Scan() {
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+ line := scanner.Text()
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+ if line == "" {
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+ continue
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+ }
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+
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+ var current monkey
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+ if strings.ContainsAny(line, "+-/*") {
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+ current.spec = op
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+ n, err := fmt.Sscanf(line, "%s %s %c %s", ¤t.name, ¤t.left, ¤t.op, ¤t.right)
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+ if n != 4 || err != nil {
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+ log.Fatal("Can't parse (op): ", line, err)
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+ }
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+ } else {
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+ current.spec = val
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+ n, err := fmt.Sscanf(line, "%s %d", ¤t.name, ¤t.value)
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+ if n != 2 || err != nil {
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+ log.Fatal("Can't parse: ", line, err)
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+ }
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+ }
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+
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+ current.name = strings.TrimRight(current.name, ":")
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+ monkeys[current.name] = current
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+ }
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+
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+ return monkeys
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+}
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+
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+func processMonkey(being monkey, monkeys map[string]monkey) int {
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+ if being.spec == val {
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+ return being.value
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+ }
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+
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+ switch being.op {
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+ case '+':
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+ return processMonkey(monkeys[being.left], monkeys) + processMonkey(monkeys[being.right], monkeys)
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+ case '-':
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+ return processMonkey(monkeys[being.left], monkeys) - processMonkey(monkeys[being.right], monkeys)
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+ case '*':
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+ return processMonkey(monkeys[being.left], monkeys) * processMonkey(monkeys[being.right], monkeys)
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+ case '/':
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+ return processMonkey(monkeys[being.left], monkeys) / processMonkey(monkeys[being.right], monkeys)
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+ }
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+
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+ return 0
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+}
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+
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+func main() {
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+ if len(os.Args) < 2 {
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+ log.Fatal("You need to specify a file!")
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+ }
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+
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+ filePath := os.Args[1]
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+ file, err := os.Open(filePath)
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+ if err != nil {
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+ log.Fatalf("Failed to open %s!\n", filePath)
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+
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+ }
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+
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+ monkeys := readInput(file)
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+ fmt.Println("Part1:", processMonkey(monkeys["root"], monkeys))
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+}
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