1 All variables, constants and other identifiers must have meaningful names. (a) Identify and give the data type and use of one array that you could have used for Task 1. Array … Data type … Use … [3] (b) Describe two validation checks that could be used when inputting the number of tickets to buy for Task 2. For each validation check give one example of normal data and one example of erroneous data. Validation check 1 … … … Normal data … Erroneous data … Validation check 2 … … … Normal data … Erroneous data … [6] (c) Write an algorithm for the part of Task 2 that inputs the tickets required, calculates the total price for the ticket(s) purchased by a passenger including a group discount (if applicable) and updates the data structures used for the totals. Use either pseudocode, programming statements or a flowchart. … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … [6] (d) Explain how your program completed Task 3. Include any programming statements that you have used and fully explain the purpose of each statement. … … … … … … … … … … … … … … … … … … … … … … … [5]

1(a) Array TrainUpPassengers // TrainUpPassengers[] Data type Integer/int Use storing the number of passengers on the train journeys up Many correct answers, this is an example. 3 1(b) One mark for description, one mark for normal data and one mark for erroneous data for two checks Validation check (type check) to check that the number entered is a whole number / integer Normal data 34 Erroneous data two // 1.5 Validation check (range check) to check that the value of the number entered is between 1 and 80 / 480 inclusive Normal data 34 Erroneous data 99 // 500 Validation check (presence check) to check that a value has been entered Normal data 34 // any data entered Erroneous data “” // blank // no data entered Validation check (length check) to check that a value has 3 digits or fewer // between 1 and 3 digits Normal data 345 Erroneous data 3456 Many correct answers, the data are examples only. 6 1(c) Any six from: MP1 Input number of tickets MP2 Input train up mountain and train down mountain MP3 Suitable prompts seen for inputs that are included MP4 Check that tickets are available on selected train(s) MP5 If available calculate price of tickets … MP6 … calculation includes discount if required MP7 Update total passengers / seats available for a train MP8 Update total passengers / seats available for up train and down train MP9 Update total cost for a train MP10 Update total cost for up train and down train Example answers OUTPUT "How many tickets" INPUT NoTickets OUTPUT "Which Train up the mountain? 1, 2, 3 or 4" INPUT UpNumber OUTPUT "Which Train down the mountain? 1, 2, 3 or 4" INPUT DownNumber IF (DownNumber = 4 AND TrainUp[UpNumber] + NoTickets <= 480 AND TrainDown[DownNumber] + NoTickets <= 640) OR (TrainUp[UpNumber] + NoTickets <= 480 AND TrainDown[DownNumber] + NoTickets <= 480) THEN Cost ← (NoTickets – NoTickets DIV 10) * 50 TrainUp[UpNumber] ← TrainUp[UpNumber] + NoTickets TrainDown[DownNumber] ← TrainUp[DownNumber] + NoTickets TrainUpTotal[UpNumber] ← TrainUpTotal[UpNumber] + Cost / 2 TrainDownTotal[DownNumber] ← TrainDownTotal[DownNumber] + Cost / 2 ENDIF 6 1(c) Yes Yes START OUTPUT "Tickets" INPUT Tickets Cost ← (NoTickets – NoTickets DIV 10) * 50 TrainUp[UpNo] ← TrainUp[UpNo] + NoTickets TrainDown[DownNo] ← TrainUp[DownNo] + NoTickets TrainUpTotal[UpNo] ← TrainUpTotal[UpNo] + Cost / 2 TrainDownTotal[DownNo] ← TrainDownTotal[DownNo] + Cost / 2 END Is Tickets <= UpTickets[UpNo] AND Tickets <= DownTickets[DownNo]? No OUTPUT "Up Train" INPUT UpNo OUTPUT "Down Train" INPUT DownNo 1(d) Explanation Any five from: MP1 How the program displayed the number of passengers for a journey ... MP2 … how completed for all trains MP3 How the program displayed the amount of money taken for a journey … MP4 … how completed for all trains MP5 How the program calculated the total number of passengers MP6 How the program calculated the total money taken MP7 How the program attempted to select the train journey with the most passengers MP8 How the program attempted to dealt with more than one train being the most popular MP9 How the program displayed the results with suitable messages Programming statements must be given with each explanation. 5

1 All variables, constants and other identifiers must have meaningful names. (a) (i) Identify one variable you could have used for Task 2 and state its use. Variable … Use … … … [2] (ii) Describe the arrays you could have used in Task 1. Include the name, data type, use and sample data for each array. … … … … … … … … … … … … [5] (b) Describe how you could validate the data entry for the input of the codes for the different stages of the journey in Task 2. … … … … … … [3] (c) Write an algorithm to show how your program carries out Task 3, using either pseudocode, programming statements or a flowchart. Assume Tasks 1 and 2 have already been completed. … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … … [6] (d) Explain how your program could be changed to count and store the number of bookings made by each passenger. Then, after ten bookings have been made by a passenger, apply an additional 10% discount to every future booking. Any programming statements used in your answer must be fully explained. … … … … … … … … … … … … … … … … … … … … … … … … … … … [4]

1(a)(i) One mark per point • Variable PassengerID// StartStage • Use Storing the unique ID number of the passenger// Storing/inputting the start stage of the journey 2 1(a)(ii) One mark per point MP1 Name of array MP2 Data type of array MP3 Sample data for array MP4 Use of array MP5 At least two complete arrays with all of the above Array name Data type Sample data Use JourneyStage1 string C1 to store the code for the home to start station PriceStage1 real 1.50 to store the price of first stage of the journey 5 1(b) One mark per bullet point MP1 Use of validation check, e.g. range check, type check, presence check, length check, format check MP2 Use of conditional statement to check if the validation fails ... MP3 … a re-entry is requested MP4 Use of loop to repeat the process until an acceptable answer is input MP5 More than one appropriate validation check used / described. 3 1(c) Any six from: MP1 Conditional statement to check departure time against 10:00 MP2 … calculate 40% discount // calculate 60% of the original price MP3 … calculate discounted total price MP4 Output the discounted total price MP5 Output the booking details with suitable messages MP6 Input with prompt for passenger confirmation … MP7 … attempt at action following the confirmation input MP8 Repeating booking data entry if incorrect MP9 Re-checking journey details for correctness 6 1(c) Example answer // Tasks 1 and 2 completed IF CollectedTime[Index] > 10:00 THEN JourneyCost[Index] ← JouneyCost[Index] * 0.6 ENDIF PRINT "Your journey cost is: ", JourneyCost[Index] PRINT "Your journey details are: ", PassengerID[Index], JourneyTime[Index], JourneyCodes[Index], JourneyID[Index] PRINT "Are these details correct? (Y or N)" INPUT Correct IF Correct = "N" THEN WHILE Correct = "N" PRINT "Re-enter your journey details" PRINT "Correct passenger ID " INPUT PassengerID[Index] PRINT "Correct journey time " INPUT JourneyTime[Index] PRINT "Correct journey codes " INPUT JourneyCodes[Index] PRINT "Your revised journey details are: ", PassengerID[Index], JourneyTime[Index], JourneyCodes[Index] PRINT "Are these details correct? (Y or N)" INPUT Correct ENDWHILE ENDIF //Program continues 1(d) Explanation of how each of the following could be done Any four from: MP1 Declaring/using a counter to store the number of bookings for each passenger MP2 Updating the counter for the number of bookings made by each passenger MP3 Attempt to check the number of bookings … MP4 … for the correct condition e.g. if the number of bookings is more than 10 / equal to 10 MP5 Apply the extra discount to the total price of future journeys 4

2 (a) Write an algorithm in pseudocode to input 500 positive whole numbers. Each number input must be less than 1000. Find and output the largest number input, the smallest number input and the range (difference between the largest number and smallest number). … … … … … … … … … … … … … … … … … … … … … … … … … [6] (b) Describe how the algorithm could be changed to make testing less time-consuming. … … … … [2]

2(a) Any six from: MP1 Initialisation of large and small variables e.g. Large ← 0 Small ← 1000 MP2 Use of a loop for 500 entries // or 499 if initialisation done on first correct entry MP3 Input with prompt MP4 Attempt at checking the range of 1 to 999 for input MP5 … working range check MP6 Checking for a whole number MP7 Selecting largest number MP8 Selecting smallest number MP9 Calculating the range MP10 Outputting the largest, smallest and range with message Large ← 0 Small ← 1000 FOR Count ← 1 TO 500 REPEAT OUTPUT "Enter a whole number between 1 and 999" INPUT Number UNTIL Number >= 1 AND Number Large THEN Large ← Number ENDIF NEXT Range ← Large – Small OUTPUT "Largest number is ", Large, " Smallest number is ", Small, " Range of numbers is ", Range 6 2(b) One mark for action required and one mark for method used Reduce the amount of numbers entered By decreasing the final value of the loop or Remove the need to input values By using random numbers / a previously populated array 2

2 Tick (3) one box in each row to identify if the statement is about validation, verification or neither. Statement Validation (3) Verification (3) Neither (3) a check where data is re-entered to make sure no errors have been introduced during data entry an automatic check to make sure the data entered has the correct number of characters a check to make sure the data entered is sensible a check to make sure the data entered is correct [3]

2 One mark for two correct rows Two marks for three correct rows Three marks for four correct rows. Statement Validation () Verification () Neither () a check where data is re-entered to make sure no errors have been introduced during data entry  an automatic check to make sure the data entered has the correct number of characters  a check to make sure the data entered is sensible  a check to make sure the data entered is correct  3

3 (a) Draw the most appropriate flowchart symbol for each pseudocode statement. Pseudocode statement Flowchart symbol IF Number = 20 PRINT Number Number ← Number + 1 [3] (b) State the type of each pseudocode statement. For example, X ← X + Y is totalling. IF Number = 20 … PRINT Number … Number ← Number + 1 … [3]

3(a) Pseudocode statement Flowchart symbol IF Number = 20 PRINT Number Number ← Number + 1 3 3(b) IF Number = 20 selection PRINT Number output Number ← Number + 1 counting 3

Cambridge O Level Computer Science · 2210

O-Level Computer Science (2210) Algorithm design and problem-solving past paper questions

Revise O-Level Computer Science (2210) — Algorithm design and problem-solving with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

93 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Algorithm design and problem-solving in O-Level Computer Science 2210 exams, 2020–2025

Across 2020–2025, Algorithm design and problem-solving accounted for 118 questions worth 978 marks in Cambridge O Level Computer Science (2210) papers.