X-Git-Url: http://git.scottworley.com/slidingtile/blobdiff_plain/212a5629d44cb0aa108057fe5a6d0c67bb479d54..2c35054f652f2d4bbf09867a871096f48e5c7af8:/sliding_tile.go

diff --git a/sliding_tile.go b/sliding_tile.go
index 32bccae..96e00dc 100644
--- a/sliding_tile.go
+++ b/sliding_tile.go
@@ -5,11 +5,19 @@ import "os"
 import "strconv"
 
 const HOLE = 0
-const BOARD_SIZE = 16
+const BOARD_DIM = 4
+const BOARD_SIZE = BOARD_DIM * BOARD_DIM
 
 type Space int8
 type Board [BOARD_SIZE]Space
 
+const (
+	LEFT  = -1
+	RIGHT = +1
+	UP    = -BOARD_DIM
+	DOWN  = +BOARD_DIM
+)
+
 func read_board_from_strings(in []string) (*Board, error) {
 	if len(in) != BOARD_SIZE {
 		return nil, fmt.Errorf("Please provide %d values", BOARD_SIZE)
@@ -25,6 +33,26 @@ func read_board_from_strings(in []string) (*Board, error) {
 	return &b, nil
 }
 
+func adjacent_spaces(s Space) []Space {
+	if s < 0 || s >= BOARD_SIZE {
+		panic("Invalid space")
+	}
+	var adjacent []Space
+	if s >= BOARD_DIM {
+		adjacent = append(adjacent, s+UP)
+	}
+	if s < BOARD_SIZE-BOARD_DIM {
+		adjacent = append(adjacent, s+DOWN)
+	}
+	if s%BOARD_DIM != 0 {
+		adjacent = append(adjacent, s+LEFT)
+	}
+	if s%BOARD_DIM != BOARD_DIM-1 {
+		adjacent = append(adjacent, s+RIGHT)
+	}
+	return adjacent
+}
+
 func main() {
 	start, err := read_board_from_strings(os.Args[1:])
 	if err != nil {