A distance metric

[slidingtile] / sliding_tile_lib.h

diff --git a/sliding_tile_lib.h b/sliding_tile_lib.h
index d144789187c7e91170b46658e37c72a53c01c5e4..c5d0a8bc66c99b7480d06a1c2b96811de9bbe6b6 100644 (file)
--- a/sliding_tile_lib.h
+++ b/sliding_tile_lib.h
@@ -7,10 +7,17 @@
 const int BOARD_DIM = 4;
 const int BOARD_SIZE = BOARD_DIM * BOARD_DIM;
 
+struct InvertedBoard {
+  signed char pos[BOARD_SIZE];
+};
+
 struct Board {
   signed char board[BOARD_SIZE];
   bool is_valid() const;
   signed char hole() const;
+  InvertedBoard invert() const;
+  int distance(const Board& o) const;
+  int distance(const InvertedBoard& invo) const;
 };
 std::istream& operator>>(std::istream& is, Board& board);
 std::ostream& operator<<(std::ostream& os, const Board& board);