package main import ( "bufio" "fmt" "log" "os" ) func readInput(file *os.File) [][]byte { scanner := bufio.NewScanner(file) var platform [][]byte for scanner.Scan() { line := scanner.Text() if line == "" { break } var row []byte for i := range line { row = append(row, line[i]) } platform = append(platform, row) } return platform } func tiltNorth(platform [][]byte, y int, x int, height int, width int) { for { prevY := y - 1 if prevY < 0 || platform[prevY][x] == '#' || platform[prevY][x] == 'O' { break } platform[y][x] = '.' platform[prevY][x] = 'O' y-- } } func tiltSouth(platform [][]byte, y int, x int, height int, width int) { for { nextY := y + 1 if nextY >= height || platform[nextY][x] == '#' || platform[nextY][x] == 'O' { break } platform[y][x] = '.' platform[nextY][x] = 'O' y++ } } func tiltEast(platform [][]byte, y int, x int, height int, width int) { for { nextX := x + 1 if nextX >= width || platform[y][nextX] == '#' || platform[y][nextX] == 'O' { break } platform[y][x] = '.' platform[y][nextX] = 'O' x++ } } func tiltWest(platform [][]byte, y int, x int, height int, width int) { for { nextX := x - 1 if nextX < 0 || platform[y][nextX] == '#' || platform[y][nextX] == 'O' { break } platform[y][x] = '.' platform[y][nextX] = 'O' x-- } } func tiltPlatform(platform [][]byte, direction func([][]byte, int, int, int, int), height int, width int) { for y := range platform { for x := range platform[y] { if platform[y][x] == 'O' { direction(platform, y, x, height, width) } } } } func tiltPlatformFromBottom(platform [][]byte, direction func([][]byte, int, int, int, int), height int, width int) { for y := height - 1; y >= 0; y-- { for x := range platform[y] { if platform[y][x] == 'O' { direction(platform, y, x, height, width) } } } } func tiltPlatformFromRight(platform [][]byte, direction func([][]byte, int, int, int, int), height int, width int) { for y := range platform { for x := width - 1; x >= 0; x-- { if platform[y][x] == 'O' { direction(platform, y, x, height, width) } } } } func calculate(platform [][]byte, height int) int { var result int for y := range platform { for x := range platform[y] { if platform[y][x] == 'O' { result += height - y } } } return result } func part1(platform [][]byte) int { height := len(platform) width := len(platform[0]) tiltPlatform(platform, tiltNorth, height, width) return calculate(platform, height) } func copyPlatform(platform [][]byte) [][]byte { var newPlatform [][]byte for y := range platform { newPlatform = append(newPlatform, platform[y]) } return newPlatform } func part2(platform [][]byte, cycles int) int { height := len(platform) width := len(platform[0]) for i := 0; i < cycles; i++ { tiltPlatform(platform, tiltNorth, height, width) tiltPlatform(platform, tiltWest, height, width) tiltPlatformFromBottom(platform, tiltSouth, height, width) tiltPlatformFromRight(platform, tiltEast, height, width) } return calculate(platform, height) } func main() { if len(os.Args) < 2 { log.Fatal("You need to specify a file!") } filePath := os.Args[1] file, err := os.Open(filePath) if err != nil { log.Fatalf("Failed to open %s!\n", filePath) } platform := readInput(file) platformCopy := copyPlatform(platform) fmt.Println("Part1:", part1(platform)) fmt.Println("Part2:", part2(platformCopy, 1000)) }