A distance metric

[slidingtile] / sliding_tile_lib.h

diff --git a/sliding_tile_lib.h b/sliding_tile_lib.h
index 84d422e2faaf09d44c663a253c1cc02c94418cb1..c5d0a8bc66c99b7480d06a1c2b96811de9bbe6b6 100644 (file)
--- a/sliding_tile_lib.h
+++ b/sliding_tile_lib.h
@@ -2,16 +2,25 @@
 #define _SLIDING_TILE_LIB_H
 
 #include <istream>
+#include <ostream>
 
 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();
-  signed char hole();
+  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);
 
 extern signed char adjacent[BOARD_SIZE][5];