A one-player game uses the two-dimensional (2D) array Grid[] to store the location of a secret cell to be found by the player in 10 moves. Each row and column has 5 cells. [Figure showing a 5x5 grid with 'Start Grid[1,1]' label] At the start of the game: • The program places an 'X' in a random cell (not in Grid[1,1]) and empties all the other cells in the grid. • The player starts at the top left of the grid. • The player has 10 moves. During the game: • The player can move left, right, up or down by one cell and the move must be within the grid. • "You Win" is displayed if the player moves to the cell with 'X' and has played 10 moves or less. • "You Lose” is displayed if the player has made 10 moves without finding the 'X'. Write a program that meets these requirements. You must use pseudocode or program code and add comments to explain how your code works. You do not need to declare any arrays or variables; you may assume that this has already been done. All inputs and outputs must contain suitable messages.

Mark scheme

Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.

1. Data Structures required with names as given in the scenario: Arrays or lists Grid
2. Requirements (techniques)
3. R1 Set up game – generate random cell, clear all other cells in array, set player start position and start player moves counter (iteration, use of arrays and library routines (round and random))
4. R2 Input and check move is it valid? (input, output, iteration and selection)
5. R3 Decide outcome – has move found the X? If so, give appropriate output. If not increment counter and continue. If 10 moves exceeded, give appropriate output (use of arrays, iteration, selection and output).
6. Example 15-mark answer in pseudocode
7. // Set up game
8. FOR Row ← 1 TO 5
9. FOR Column ← 1 TO 5
10. Grid[Row, Column] ← ''// set grid cells to be empty
11. NEXT Column
12. NEXT Row
13. REPEAT // not in cell 1,1
14. XRow ← ROUND ((RANDOM() * 4) + 1,0) // Random row position between 1 and 5 in GRID
15. XColumn ← ROUND ((RANDOM() * 4) + 1,0) // Random column position between 1 and 5 in GRID
16. UNTIL XRow <> 1 and XColumn <> 1 // not in cell 1,1
17. Grid [XRow, XColumn] ← 'X'
18. MaxMove ← 10
19. NumberMoves ← 0
20. PlayerRow ← 1
21. PlayerColumn ← 1
22. Win ← FALSE
23. // during game
24. WHILE NumberMoves < MaxMove AND NOT Win
25. MoveError ← FALSE
26. OUTPUT "Please enter your move, L - Left, R - Right, U - Up or D - Down"
27. INPUT UPPER(PlayerMove)
28. REPEAT
29. CASE OF PlayerMove
30. 'L' : TempColumn ← PlayerColumn - 1
31. 'R' : TempColumn ← PlayerColumn + 1
32. 'U' : TempRow ← PlayerRow - 1
33. 'D' : TempRow ← PlayerRow + 1
34. OTHERWISE MoveError ← TRUE
35. ENDCASE
36. // check for out-of-range moves
37. IF TempColumn < 1 or TempColumn > 5
38. THEN
39. MoveError ← TRUE
40. ELSE
41. PlayerColumn ← TempColumn
42. ENDIF
43. IF TempRow < 1 or TempRow > 5
44. THEN
45. MoveError ← TRUE
46. ELSE
47. PlayerRow ← TempRow
48. ENDIF
49. // check win if X Found
50. IF Grid [PlayerRow, PlayerColumn] = 'X'
51. THEN
52. OUTPUT "You Win"
53. Win ← TRUE
54. ELSE
55. IF NOT MoveError
56. THEN
57. NumberMoves ← NumberMoves + 1
58. ENDIF
59. ENDIF
60. UNTIL NOT MoveError
61. ENDWHILE
62. IF NOT Win
63. THEN
64. OUTPUT "You Lose"
65. ENDIF