Computer Science · May / June 2024 · Paper 22 · Question 11
0478
As printed in the paper
The question as text
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. Start Grid[1,1] 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.
Read automatically from the paper; the printed page above is exact.
Show the answer and mark scheme
Data Structures required with names as given in the scenario:
Arrays or lists Grid
Requirements (techniques)
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))
R2 Input and check move – is it valid? (input, output, iteration and selection)
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).
Example 15-mark answer in pseudocode
// Set up game
FOR Row ← 1 TO 5
FOR Column ← 1 TO 5
Grid[Row, Column] ← ''// set grid cells to be empty
NEXT Column
NEXT Row
REPEAT // not in cell 1,1
XRow ← ROUND ((RANDOM() * 4) + 1, 0) // Random row position between 1 and 5 in GRID XColumn ← ROUND ((RANDOM() * 4) + 1, 0) // Random column position between 1 and 5 in GRID
UNTIL XRow <> 1 and XColumn <> 1 // not in cell 1,1
Grid [XRow, XColumn] ← 'X'
MaxMove ← 10
NumberMoves ← 0
PlayerRow ← 1
PlayerColumn ← 1
Win ← FALSE
// during game
WHILE NumberMoves < MaxMove AND NOT Win
MoveError ← FALSE
OUTPUT "Please enter your move, L – Left, R – Right, U – Up or D - Down"
INPUT UPPER(PlayerMove)
REPEAT
CASE OF PlayerMove
'L' : TempColumn ← PlayerColumn – 1
'R' : TempColumn ← PlayerColumn + 1
'U' : TempRow ← PlayerRow – 1
'D' : TempRow ← PlayerRow + 1
OTHERWISE MoveError ← TRUE
ENDCASE
// check for out-of-range moves
IF TempColumn < 1 or TempColumn > 5
THEN
MoveError ← TRUE
ELSE
PlayerColumn ← TempColumn
ENDIF
IF TempRow < 1 or TempRow > 5
THEN
MoveError ← TRUE
ELSE
PlayerRow ← TempRow
ENDIF
// check win if X Found
IF Grid [PlayerRow, PlayerColumn] = 'X'
THEN
OUTPUT "You Win"
Win ← TRUE
ELSE
IF NOT MoveError
THEN
NumberMoves ← NumberMoves + 1
ENDIF
ENDIF
UNTIL NOT MoveError
ENDWHILE
IF NOT Win
THEN
OUTPUT "You Lose"
ENDIF
AO2: Apply knowledge and understanding of the principles and concepts of computer science to a given context, including the analysis and design of computational or programming problems
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