84 lines
1.8 KiB
Go
84 lines
1.8 KiB
Go
package dayfour
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import (
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"advent-of-code/internal/registry"
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"os"
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"regexp"
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"sort"
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"strconv"
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"strings"
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)
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func init() {
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registry.Register("2016D4", ParseInput, PartOne, PartTwo)
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}
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func ParseInput(filepath string) []string {
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content, _ := os.ReadFile(filepath)
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return strings.Split(string(content), "\n")
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}
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func isValidRoom(encryptedName string, expectedChecksum string) bool {
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letterFrequency := [26]int{}
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for _, character := range encryptedName {
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if character >= 'a' && character <= 'z' {
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letterFrequency[character-'a']++
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}
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}
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type letterFrequencyPair struct {
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letter rune
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count int
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}
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letterFrequencyPairs := make([]letterFrequencyPair, 0, 26)
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for index, frequency := range letterFrequency {
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if frequency > 0 {
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letterFrequencyPairs = append(letterFrequencyPairs, letterFrequencyPair{
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letter: rune('a' + index),
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count: frequency,
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})
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}
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}
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sort.Slice(letterFrequencyPairs, func(i, j int) bool {
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if letterFrequencyPairs[i].count != letterFrequencyPairs[j].count {
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return letterFrequencyPairs[i].count > letterFrequencyPairs[j].count
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}
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return letterFrequencyPairs[i].letter < letterFrequencyPairs[j].letter
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})
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if len(letterFrequencyPairs) < 5 {
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return false
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}
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for index := range 5 {
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if letterFrequencyPairs[index].letter != rune(expectedChecksum[index]) {
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return false
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}
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}
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return true
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}
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var roomPattern = regexp.MustCompile(`^(.+)-(\d+)\[([a-z]{5})\]$`)
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func PartOne(data []string) int {
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sum := 0
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for _, line := range data {
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matches := roomPattern.FindStringSubmatch(line)
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encryptedName := matches[1]
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sectorIdentifier, _ := strconv.Atoi(matches[2])
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actualChecksum := matches[3]
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if isValidRoom(encryptedName, actualChecksum) {
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sum += sectorIdentifier
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}
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}
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return sum
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}
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func PartTwo(data []string) int {
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return 0
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}
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