110 lines
2.5 KiB
Go
110 lines
2.5 KiB
Go
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package main
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import (
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"os"
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"fmt"
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"strconv"
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"strings"
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)
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// data types
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type Path struct {
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start_x int
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start_y int
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end_x int
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end_y int
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}
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// general util
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func check(e error) {
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if e != nil { panic(e) }
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}
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func get_next_steps(field [][]byte, path *Path) []Path {
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paths := make([]Path, 0, 4)
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x := path.end_x
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y := path.end_y
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val := field[y][x]
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if y < len(field) - 1 {
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down := field[y + 1][x]
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if down == val + 1 {
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paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x, end_y: y + 1 })
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}
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}
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if y > 0 {
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up := field[y - 1][x]
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if up == val + 1 {
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paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x, end_y: y - 1 })
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}
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}
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if x < len(field[0]) - 1 {
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right := field[y][x + 1]
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if right == val + 1 {
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paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x + 1, end_y: y })
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}
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}
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if x > 0 {
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left := field[y][x - 1]
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if left == val + 1 {
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paths = append(paths, Path{ start_x: path.start_x, start_y: path.start_y, end_x: x - 1, end_y: y })
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}
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}
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return paths
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}
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func get_all_paths(field [][]byte) []Path {
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paths := make([]Path, 0)
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// init
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for _y, line := range field {
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for _x, val := range line {
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if val == 0 {
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paths = append(paths, Path{start_x: _x, end_x: _x, start_y: _y, end_y: _y})
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}
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}
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}
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// step by step
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for i := 0; i < 9; i++ {
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new_paths := make([]Path, 0, len(paths))
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for _, path := range paths {
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new_paths = append(new_paths, get_next_steps(field, &path)...)
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}
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paths = new_paths
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}
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return paths
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}
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// main loop
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func main() {
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// read in file
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dat, err := os.ReadFile("data.txt")
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check(err)
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dat_str := strings.TrimSpace(string(dat))
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// contruct input as byte matrix
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lines := strings.Split(dat_str, "\n")
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input := make([][]byte, 0, len(lines))
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for _, line := range lines {
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matrix_line := make([]byte, 0, len(line))
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for _, char := range []rune(line) {
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num, err := strconv.Atoi(string(char))
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check(err)
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matrix_line = append(matrix_line, byte(num))
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}
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input = append(input, matrix_line)
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}
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// calc scores
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m := make(map[Path]bool)
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for _, path := range get_all_paths(input) {
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m[path] = true
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}
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fmt.Println(len(m))
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}
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