80 lines
1.3 KiB
Go
80 lines
1.3 KiB
Go
package dayfive
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import (
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"advent-of-code/internal/registry"
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"os"
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"strings"
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)
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func init() {
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registry.Register("2020D5", ParseInput, PartOne, PartTwo)
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}
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func calculateSeatID(pass string) int {
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if len(pass) < 10 {
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return -1
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}
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rowStr := pass[:7]
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columnStr := pass[7:10]
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row := 0
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for idx, char := range rowStr {
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if char == 'B' {
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row |= 1 << (6 - idx)
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}
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}
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column := 0
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for idx, char := range columnStr {
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if char == 'R' {
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column |= 1 << (2 - idx)
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}
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}
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return row*8 + column
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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 PartOne(data []string) int {
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maxSeatID := 0
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for _, pass := range data {
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seatID := calculateSeatID(pass)
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if seatID > maxSeatID {
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maxSeatID = seatID
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}
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}
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return maxSeatID
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}
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func PartTwo(data []string) int {
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seatIDs := make(map[int]bool)
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minSeatID := 1000
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maxSeatID := 0
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for _, pass := range data {
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if len(pass) < 10 {
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continue
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}
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seatID := calculateSeatID(pass)
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seatIDs[seatID] = true
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if seatID < minSeatID {
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minSeatID = seatID
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}
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if seatID > maxSeatID {
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maxSeatID = seatID
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}
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}
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for seatID := minSeatID + 1; seatID < maxSeatID; seatID++ {
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if !seatIDs[seatID] && seatIDs[seatID-1] && seatIDs[seatID+1] {
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return seatID
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}
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}
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return 0
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}
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