Adjacent spaces

diff --git a/sliding_tile.go b/sliding_tile.go
index 32bccae239b9b0c9a1f8b989c5396c4bc527fe93..96e00dcc85645a6d997a878028adf06bf42e4af6 100644 (file)
--- 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 {

diff --git a/sliding_tile_test.go b/sliding_tile_test.go
index 28392eef4599c4b9cd9d0a7968b57a8325d1a16c..34f3fcc5ba46af1b78dd61b262c293b4efaf2189 100644 (file)
--- a/sliding_tile_test.go
+++ b/sliding_tile_test.go
@@ -1,5 +1,7 @@
 package main
 
+import "reflect"
+import "sort"
 import "testing"
 
 func Test_read_board_from_strings(t *testing.T) {
@@ -26,3 +28,43 @@ func Test_read_board_from_strings(t *testing.T) {
                t.Fail()
        }
 }
+
+// For sorting, for unordered equality testing
+type Spaces []Space
+
+func (s Spaces) Len() int           { return len(s) }
+func (s Spaces) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s Spaces) Less(i, j int) bool { return s[i] < s[j] }
+
+func Test_adjacent_spaces(t *testing.T) {
+       type TestCase struct {
+               s        Space
+               expected Spaces
+       }
+       cases := []TestCase{
+               {0, []Space{1, 4}},
+               {1, []Space{0, 2, 5}},
+               {2, []Space{1, 3, 6}},
+               {3, []Space{2, 7}},
+               {4, []Space{0, 5, 8}},
+               {5, []Space{1, 4, 6, 9}},
+               {6, []Space{2, 5, 7, 10}},
+               {7, []Space{3, 6, 11}},
+               {8, []Space{4, 9, 12}},
+               {9, []Space{5, 8, 10, 13}},
+               {10, []Space{6, 9, 11, 14}},
+               {11, []Space{7, 10, 15}},
+               {12, []Space{8, 13}},
+               {13, []Space{9, 12, 14}},
+               {14, []Space{10, 13, 15}},
+               {15, []Space{11, 14}},
+       }
+       for i, c := range cases {
+               var actual Spaces = adjacent_spaces(c.s)
+               sort.Sort(c.expected)
+               sort.Sort(actual)
+               if !reflect.DeepEqual(c.expected, actual) {
+                       t.Error(i, c.expected, actual)
+               }
+       }
+}