89 lines
1.9 KiB
Go
89 lines
1.9 KiB
Go
package dayfour
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import (
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"os"
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"regexp"
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"slices"
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"strconv"
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"strings"
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"time"
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"advent-of-code/internal/registry"
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)
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var guardRegex = regexp.MustCompile(`Guard #(\d+) begins shift`)
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func init() {
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registry.Register("2018D4", 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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type record struct {
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timestamp time.Time
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action string
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guardID int
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}
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func PartOne(data []string) int {
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records := make([]record, 0, len(data))
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timeLayout := "2006-01-02 15:04"
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for _, line := range data {
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timeStr, action, _ := strings.Cut(line[1:], "] ")
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timestamp, _ := time.Parse(timeLayout, timeStr)
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guardID := -1
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if matches := guardRegex.FindStringSubmatch(action); matches != nil {
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guardID, _ = strconv.Atoi(matches[1])
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}
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records = append(records, record{timestamp, action, guardID})
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}
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slices.SortFunc(records, func(a, b record) int {
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return a.timestamp.Compare(b.timestamp)
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})
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guardSleepMinutes := make(map[int]int)
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guardMinuteCount := make(map[int]map[int]int)
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currentGuard := -1
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for i := range records {
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if records[i].guardID != -1 {
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currentGuard = records[i].guardID
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if guardMinuteCount[currentGuard] == nil {
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guardMinuteCount[currentGuard] = make(map[int]int)
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}
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}
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if records[i].action == "falls asleep" && i+1 < len(records) {
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start, end := records[i].timestamp.Minute(), records[i+1].timestamp.Minute()
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guardSleepMinutes[currentGuard] += end - start
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for m := start; m < end; m++ {
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guardMinuteCount[currentGuard][m]++
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}
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}
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}
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maxGuard, maxMinutes := -1, 0
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for id, minutes := range guardSleepMinutes {
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if minutes > maxMinutes {
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maxGuard, maxMinutes = id, minutes
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}
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}
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maxMinute, maxCount := -1, 0
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for m, count := range guardMinuteCount[maxGuard] {
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if count > maxCount {
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maxMinute, maxCount = m, count
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}
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}
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return maxGuard * maxMinute
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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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