AoC2020/day19/day19.go
Karl Spickermann b315cdff0e Day19
2020-12-20 00:49:34 +01:00

75 lines
1.6 KiB
Go

package main
import (
"AoC2020/helper"
"fmt"
"os"
"regexp"
"strings"
)
func main() {
lineBreak := "\n"
args := os.Args[1:]
input, err := helper.GetFile(args[0])
if err != nil {
fmt.Println(err)
}
parsedInput := strings.Split(input, lineBreak+lineBreak)
rulesInput := strings.Split(parsedInput[0], lineBreak)
messagesInput := strings.Split(parsedInput[1], lineBreak)
var rules = make(map[string]string)
for _, val := range rulesInput {
cleanS := strings.Replace(val, "\"","",-1)
parsedRule := strings.Split(cleanS,": ")
rules[parsedRule[0]] = parsedRule[1]
}
regex := getSummedRule(rules,"0")
fmt.Println(regex)
count := getValidMessages(regex, messagesInput)
fmt.Println(count)
rules["8"] = rules["8"] + " +"
newRule11 := rules["11"]
for i:= 0; i< 10; i++{
newRule11 = "42 " + newRule11 + " 31"
rules["11"] = rules["11"] + " | " + newRule11
}
regex = getSummedRule(rules,"0")
fmt.Println(regex)
count = getValidMessages(regex, messagesInput)
fmt.Println(count)
}
func getValidMessages(regex string, messagesInput []string) int {
r, _ := regexp.Compile("^" + regex + "$")
count := 0
for _, val := range messagesInput {
if r.MatchString(val) {
count++
}
}
return count
}
func getSummedRule(rules map[string]string, rule string) string{
r, _ := regexp.Compile("[0-9]")
if rule == "+"{
return rule
}
number := r.FindString(rules[rule])
if number == "" {
return rules[rule]
}
stringParts := strings.Split(rules[rule],"|")
newRule := ""
for _, val := range stringParts {
newRule += "|"
for _, s := range strings.Fields(val) {
newRule += getSummedRule(rules,s)
}
}
return "(" + newRule[1:] + ")"
}