81 lines
1.4 KiB
Go
81 lines
1.4 KiB
Go
package main
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import (
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"bufio"
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"fmt"
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"io"
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"log"
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"math"
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"os"
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"strings"
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)
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type Seat string
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func half(chain string, size int, lower rune, upper rune) int {
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rowPart := chain[0:int(math.Log2(float64(size)))]
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half := size / 2
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row := 0
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for _, c := range rowPart {
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switch c {
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case lower:
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case upper:
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row += half
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default:
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panic("wrong letter")
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}
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half /= 2
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}
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return row
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}
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func (s Seat) Row() int {
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return half(string(s[0:7]), 128, 'F', 'B')
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}
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func (s Seat) Col() int {
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return half(string(s[7:10]), 8, 'L', 'R')
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}
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func (s Seat) ID() int {
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return (s.Row() * 8) + s.Col()
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}
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func (s Seat) String() string {
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return fmt.Sprintf("row %d, col %d, ID %d", s.Row(), s.Col(), s.ID())
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}
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func main() {
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// I'm lazy and need this done quick
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seats := map[int]Seat{}
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f, err := os.Open("input")
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if err != nil {
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panic(err)
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}
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r := bufio.NewReader(f)
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for {
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line, err := r.ReadString('\n')
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if err == io.EOF {
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break
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}
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if err != nil {
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panic(err)
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}
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line = strings.TrimSpace(line)
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seat := Seat(line)
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seatID := seat.ID()
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seats[seatID] = seat
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}
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// skip row 0 and row 127
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for seatID := 8; seatID < (128-1)*8; seatID++ {
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// has ID + 1 and ID - 1?
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if _, exists := seats[seatID]; !exists {
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if _, hasSeatIDPlus1 := seats[seatID+1]; hasSeatIDPlus1 {
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if _, hasSeatIDMinus1 := seats[seatID-1]; hasSeatIDMinus1 {
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log.Printf("Matching seat ID: %d", seatID)
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}
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}
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}
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}
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}
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