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126 lines
2.6 KiB
126 lines
2.6 KiB
package main
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import (
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"bufio"
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"fmt"
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"os"
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"reflect"
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"strings"
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)
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func main() {
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var scannedSeats, currentSeats [][]rune
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file, _ := os.Open("input.txt")
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defer file.Close()
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for scanner := bufio.NewScanner(file); scanner.Scan(); {
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row := []rune{}
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for _, r := range scanner.Text() {
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row = append(row, r)
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}
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scannedSeats = append(scannedSeats, row)
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}
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// Part 1
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currentSeats = scannedSeats
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rounds:
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for {
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newSeats := [][]rune{}
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for i := range currentSeats {
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row := []rune{}
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for j, r := range currentSeats[i] {
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newRune := r
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if os := occupiedAdjacent(currentSeats, position{i, j}); r == 'L' && os == 0 {
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newRune = '#'
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} else if r == '#' && os >= 4 {
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newRune = 'L'
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}
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row = append(row, newRune)
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}
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newSeats = append(newSeats, row)
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}
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if reflect.DeepEqual(currentSeats, newSeats) {
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break rounds
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}
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currentSeats = newSeats
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}
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fmt.Println("Part 1:", countOccupied(currentSeats))
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// Part 2
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currentSeats = scannedSeats
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rounds2:
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for {
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newSeats := [][]rune{}
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for i := range currentSeats {
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row := []rune{}
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for j, r := range currentSeats[i] {
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newRune := r
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if cs := canSeeAdjacent(currentSeats, position{i, j}); r == 'L' && cs == 0 {
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newRune = '#'
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} else if r == '#' && cs >= 5 {
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newRune = 'L'
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}
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row = append(row, newRune)
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}
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newSeats = append(newSeats, row)
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}
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if reflect.DeepEqual(currentSeats, newSeats) {
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break rounds2
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}
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currentSeats = newSeats
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}
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fmt.Println("Part 2:", countOccupied(currentSeats))
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}
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type position struct {
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row, pos int
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}
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var dirs = []position{
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{-1, -1}, {-1, 0}, {-1, 1}, {0, -1}, {0, 1}, {1, -1}, {1, 0}, {1, 1},
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}
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func direction(pos, dir position) position {
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return position{pos.row + dir.row, pos.pos + dir.pos}
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}
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func isSafe(seats [][]rune, p position) bool {
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return !(p.row < 0 || p.row >= len(seats) || p.pos < 0 || p.pos >= len(seats[p.row]))
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}
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func occupied(seats [][]rune, p position) bool {
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return isSafe(seats, p) && seats[p.row][p.pos] == '#'
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}
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func occupiedAdjacent(seats [][]rune, pos position) (o int) {
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for _, dir := range dirs {
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if occupied(seats, direction(pos, dir)) {
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o++
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}
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}
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return
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}
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func canSee(seats [][]rune, p, dir position) bool {
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return isSafe(seats, p) && seats[p.row][p.pos] != 'L' && (seats[p.row][p.pos] == '#' || canSee(seats, direction(p, dir), dir))
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}
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func canSeeAdjacent(seats [][]rune, pos position) (o int) {
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for _, dir := range dirs {
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if canSee(seats, direction(pos, dir), dir) {
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o++
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}
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}
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return
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}
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func countOccupied(seats [][]rune) (o int) {
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for _, ro := range seats {
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o += strings.Count(string(ro), "#")
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}
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return
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}
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