Pointers. The Rectangle Game. Robb T. Koether. Hampden-Sydney College. Mon, Jan 21, 2013

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1 Pointers The Rectangle Game Robb T. Koether Hampden-Sydney College Mon, Jan 21, 2013 Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

2 1 Introduction 2 The Game Board 3 The Move Class 4 Strategy 5 The solve_puzzle() Function 6 Other Functions Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

3 Outline 1 Introduction 2 The Game Board 3 The Move Class 4 Strategy 5 The solve_puzzle() Function 6 Other Functions Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

4 The Rectangle Puzzle The Rectangle Puzzle is like the Triangle Puzzle, but it is played on a rectangle. The game board is a rectangular array of holes. Every hole but one contains a peg. A legal move is to use one peg to jump an adjacent peg, vertically or horizontally, into an empty hole. The object of the game is to eliminate all but one peg. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

5 Example A 3 4 rectangle game Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

6 Example (0, 2) jumps (0, 1) into (0, 0) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

7 Example (2, 2) jumps (1, 2) into (0, 2) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

8 Example (0, 3) jumps (0, 2) into (0, 1) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

9 Example (0, 0) jumps (0, 1) into (0, 2) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

10 Example (2, 3) jumps (1, 3) into (0, 3) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

11 Example (1, 0) jumps (1, 1) into (1, 2) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

12 Example (2, 0) jumps (2, 1) into (2, 2) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

13 Example (0, 3) jumps (0, 2) into (0, 1) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

14 Example (2, 2) jumps (1, 2) into (0, 2) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

15 Example (0, 2) jumps (0, 1) into (0, 0) Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

16 Outline 1 Introduction 2 The Game Board 3 The Move Class 4 Strategy 5 The solve_puzzle() Function 6 Other Functions Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

17 The Game Board The user will enter the dimensions of the game board (number of rows and number of columns). The game board size is limited to 8 8. The game board is a two-dimensional array of bools, initialized to true, meaning there is a peg in each hole. bool board[8][8]; The user will enter the position of the empty hole. That element of the game board will be set to false, meaning no peg. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

18 Outline 1 Introduction 2 The Game Board 3 The Move Class 4 Strategy 5 The solve_puzzle() Function 6 Other Functions Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

19 The Move Class I will provide a Move class. A Move object is a triple of Point2D objects, representing a possible move. Point2D jmpr; Point2D jmpd; Point2D dest; For example, {(0, 0), (0, 1), (0, 2)} is a possible move. It is a legal move is board[0][0] and board[0][1] are true and board[0][2] is false. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

20 The Possible Moves On an r c game board, how many possible moves are there? I will provide a function that will create an array of all possible moves. Move poss_move[196]; Why 196? Given the dimensions of the game board, the function will initialize the array. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

21 Outline 1 Introduction 2 The Game Board 3 The Move Class 4 Strategy 5 The solve_puzzle() Function 6 Other Functions Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

22 Strategy The strategy is to scan the list of possible moves, from first to last. As soon as a legal move is found, take it. That is, update the game board. After taking the move, scan the list again, from first to last, for the next move, and so on. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

23 Outline 1 Introduction 2 The Game Board 3 The Move Class 4 Strategy 5 The solve_puzzle() Function 6 Other Functions Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

24 The solve_puzzle() Function To simplify the management of the moves, write a recursive function solve_puzzle(). bool solve_puzzle(bool board[][8], Move poss[], int size int num_moves); The function will scan the list for the next legal move. When it finds one, it Updates the game board, Increments num_moves, and Calls on solve_puzzle(). Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

25 The solve_puzzle() Function If num_moves equals the necessary number to solve the puzzle, then solve_puzzle() returns true. If the recursive call to solve_puzzle() returns false, then the function will scan the list for the next legal move and repeat the above procedure. If the function reaches the end of the list of possible moves, then it returns false. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

26 Outline 1 Introduction 2 The Game Board 3 The Move Class 4 Strategy 5 The solve_puzzle() Function 6 Other Functions Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

27 Other Functions I suggest that you write some helpful functions. bool is_legal(bool board[ ][8], Move m); void make_move(bool board[][8], Move m); void undo_move(bool board[][8], Move m); Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

28 The is_legal() Function The is_legal() function will return true if the specified move is legal, given the current game board. This function needs to test whether the jumper and jumped holes are occupied and whether the destination hole is open. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

29 The make_move() Function The make_move() function will update the game board by Setting the jumper and jumped positions to false, and Setting the destination position to true. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

30 The undo_move() Function The undo_move() function will do the reverse of the make_move() function. Set the jumper and jumped positions to true, and Set the destination position to false. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

31 Project 1 The project is due by midnight, Monday, January 28. Turn in only the files that contain your work. Name the folder Project 1 and drag it to the dropbox. Robb T. Koether (Hampden-Sydney College) Pointers Mon, Jan 21, / 21

Recursive Triangle Puzzle

Recursive Triangle Puzzle Lecture 36 Section 14.7 Robb T. Koether Hampden-Sydney College Fri, Dec 7, 2012 Robb T. Koether (Hampden-Sydney College) Recursive Triangle Puzzle Fri, Dec 7, 2012 1 / 17 1 The