Algorithm design and problem-solving Banker

1. (a) Name the validation check described by each statement.(i) Checks that a value is between a lower and an upper limit.(ii) Checks that data has been entered and the field is not left empty.(iii) Checks that the data is a whole number and not text.(iv) Checks that data follows a set pattern, such as two letters followed by four digits. [4]

1. (a) Explain the difference between validation and verification. [2]
2. (b) Describe two methods of verification that could be used when a new customer's details are typed into a shop's computer. [2]

1. (a) A program asks the user to enter a month number. The month must be a whole number from 1 to 12. Write pseudocode that repeatedly asks for the month until a valid value is entered, and outputs a suitable message each time an invalid value is entered. [4]

1. (a) A warehouse uses 4-digit product codes followed by a check digit. The check digit is calculated as follows:- multiply the 1st, 2nd, 3rd and 4th digits by 4, 3, 2 and 1 respectively- add the results- the check digit is the remainder when the total is divided by 10.Calculate the check digit for the code 3706. Show your working. [2]
2. (b) A worker types the code 52816. Show whether this code is valid. [2]
3. (c) The worker meant to type 52186. Explain how the check digit detects this kind of error. [1]

1. (a) A games website requires a username that:- is not empty- is between 6 and 12 characters long (inclusive)- starts with an upper-case letter A to Z.Write pseudocode that inputs a username and keeps asking until it meets all three rules. Output a message saying which rule was broken each time the username is rejected. Use the functions LENGTH() and SUBSTRING(). [6]

1. (a) An online form for a college in Peshawar collects these fields. For each field, identify one suitable validation check and explain why it is suitable.(i) Date of birth(ii) National identity card number, written as 5 digits, a hyphen, 7 digits, a hyphen and 1 digit(iii) Mobile phone number(iv) Applicant's family name [4]
2. (b) An applicant enters a date of birth that passes every validation check but is still wrong. Explain how this is possible. [1]

Total ← 0Count ← 0INPUT NumWHILE Num <> -1 DO IF Num > 10 THEN Total ← Total + Num Count ← Count + 1 ENDIF INPUT NumENDWHILEOUTPUT Total, " ", Count

1. (a) Complete a trace table for the algorithm using the input data 12, 5, 30, 10, 18, -1. Use the columns Num, Total, Count and OUTPUT. [4]
2. (b) State the purpose of the algorithm. [2]

FOR Index ← 1 TO 4 IF Data[Index] > Data[Index + 1] THEN Temp ← Data[Index] Data[Index] ← Data[Index + 1] Data[Index + 1] ← Temp ENDIFNEXT Index

1. (a) The array Data contains 27, 14, 35, 9, 20 in elements 1 to 5. Complete a trace table for the algorithm with the columns Index, Temp, Data[1], Data[2], Data[3], Data[4], Data[5]. [4]
2. (b) State the name of the standard method this algorithm is part of, and explain why it must be repeated to finish the task. [2]

DECLARE Number, Sum, Digits : INTEGERINPUT NumberSum ← 0Digits ← 0REPEAT Sum ← Sum + MOD(Number, 10) Number ← DIV(Number, 10) Digits ← Digits + 1UNTIL Number = 0OUTPUT Digits, " ", Sum

1. (a) Complete a trace table for the algorithm when the input is 40725. Use the columns Number, Sum, Digits and OUTPUT. [4]
2. (b) Explain what the functions MOD and DIV do in this algorithm. [2]

Run ← 0Longest ← 0FOR Day ← 1 TO 8 IF Rain[Day] > 0 THEN Run ← Run + 1 IF Run > Longest THEN Longest ← Run ENDIF ELSE Run ← 0 ENDIFNEXT DayOUTPUT Longest

1. (a) The array Rain[1:8] holds the daily rainfall in mm for one week and a day in Murree: 0, 4, 7, 0, 2, 3, 5, 0. Complete a trace table with the columns Day, Run, Longest and OUTPUT. [4]
2. (b) State the purpose of the algorithm. [1]
3. (c) Explain what would happen if the line Run ← 0 inside the ELSE were removed. [2]

REPEAT Swapped ← FALSE FOR Index ← 1 TO 3 IF Data[Index] > Data[Index + 1] THEN Temp ← Data[Index] Data[Index] ← Data[Index + 1] Data[Index + 1] ← Temp Swapped ← TRUE ENDIF NEXT IndexUNTIL Swapped = FALSE

1. (a) The array Data holds 8, 3, 6, 1 in elements 1 to 4. Complete a trace table for the algorithm with the columns Swapped, Index, Temp, Data[1], Data[2], Data[3], Data[4]. Show each value of Swapped when it is set. [5]
2. (b) State how many times the REPEAT loop is executed for this data. [1]

1. (a) State the purpose of each flowchart symbol.(i) A rounded rectangle (terminator)(ii) A rectangle(iii) A diamond(iv) A parallelogram [4]

This algorithm inputs five temperatures in degrees Celsius and outputs each one converted to degrees Fahrenheit using F = C × 9 ÷ 5 + 32.DECLARE Celsius, Fahrenheit : REALDECLARE Count : INTEGERFOR Count ← 1 TO 5 OUTPUT "Enter temperature in Celsius" ....(1).... Celsius Fahrenheit ← Celsius * ....(2).... + 32 OUTPUT "Fahrenheit: ", ....(3)........(4).... Count

1. (a) Complete the pseudocode by writing the missing items (1) to (4). [4]

DECLARE Amount : REALDECLARE Years : INTEGERINPUT AmountYears ← 0WHILE Amount < 200000 DO Amount ← Amount * 1.08 Years ← Years + 1ENDWHILEOUTPUT Years

1. (a) State the purpose of the algorithm. [2]
2. (b) State the output when the input is 100000. [1]
3. (c) Explain why the output would be 0 if the input were 250000. [1]

1. (a) A new user of a library system must set a password. Write pseudocode that:- asks the user to enter a new password- asks the user to enter the password again- if the two entries match, outputs "Password set"- if they do not match, outputs "Passwords do not match" and asks for both entries again, until they match. [5]
2. (b) State the name of this method of verification. [1]

1. (a) An email address is accepted only if it contains exactly one "@" character and at least one "." after the "@". Write pseudocode that inputs an email address, checks it using these rules, and keeps asking until a valid address is entered. Use the functions LENGTH() and SUBSTRING(). [6]

01 DECLARE Total : INTEGER02 DECLARE Mark : INTEGER03 DECLARE Count : INTEGER04 DECLARE Average : INTEGER05 Total ← 006 FOR Count ← 1 TO 1007 OUTPUT Mark08 Total ← Total + Mark09 NEXT Count10 Average ← Total / 511 OUTPUT "Average mark is ", Average

1. (a) The algorithm should input 10 test marks and output their average, but it contains three errors. Identify the line number of each error and write the corrected line. [3]
2. (b) Explain why the data type on line 04 needed to be changed. [1]

01 DECLARE Age : STRING02 OUTPUT "Enter your age (16 to 60)"03 REPEAT04 INPUT Age05 IF Age < 16 AND Age > 60 THEN06 OUTPUT "Invalid age, try again"07 ENDIF08 NEXT09 OUTPUT "Age accepted"

1. (a) The algorithm should keep asking for an age until a whole number from 16 to 60 inclusive is entered. Identify the three errors, giving the line number and the correction for each. [3]
2. (b) Explain why the original line 05 would never output the message. [1]

01 DECLARE Temps : ARRAY[1:20] OF REAL02 DECLARE Highest : REAL03 DECLARE Day : INTEGER04 DECLARE HotDay : INTEGER05 Highest ← 006 FOR Day ← 1 TO 1907 IF Temps[Day] < Highest THEN08 Highest ← Temps[Day]09 HotDay ← Highest10 ENDIF11 NEXT Day12 OUTPUT "Highest: ", Highest, " on day ", HotDay

1. (a) The array Temps[1:20] already holds 20 winter temperatures recorded at a hill station, some of them below zero. The algorithm should output the highest temperature and the day on which it occurred. Identify the four errors, giving the line number and the correction for each. [4]
2. (b) Explain why setting Highest to 0 could give a wrong result for this data. [1]

01 DECLARE Names : ARRAY[1:50] OF STRING02 DECLARE Target : STRING03 DECLARE Index : INTEGER04 DECLARE Found : BOOLEAN05 OUTPUT "Enter the name to find"06 INPUT Target07 Found ← TRUE08 Index ← 009 WHILE Index <= 50 OR Found = FALSE DO10 IF Names[Index] = Target THEN11 Found ← TRUE12 ELSE13 Index ← Index + 114 ENDIF15 ENDIF16 IF Found = TRUE THEN17 OUTPUT Target, " found at position ", Index18 ELSE19 OUTPUT Index, " not found"20 ENDIF

1. (a) The array Names[1:50] already holds 50 student names. The algorithm should search for a name entered by the user and output its position, or a message if it is not found. Identify the five errors, giving the line number and the correction for each. [5]
2. (b) State the name of this standard searching method. [1]

1. (a) Name the standard method shown in each pseudocode fragment.(i) Total ← Total + Price[Item](ii) IF Score[P] > 50 THEN Passes ← Passes + 1 ENDIF(iii) IF Height[K] > Tallest THEN Tallest ← Height[K] ENDIF(iv) IF Code[J] = SearchCode THEN Found ← TRUE ENDIF [4]

The array List[1:10] holds 10 names.Last ← 9REPEAT Swap ← FALSE FOR J ← 1 TO Last IF List[J] > List[J + 1] THEN Temp ← List[J] List[J] ← List[J + 1] List[J + 1] ← Temp Swap ← TRUE ENDIF NEXT J Last ← Last - 1UNTIL Swap = FALSE OR Last = 0

1. (a) State the purpose of the algorithm. [2]
2. (b) Explain the purpose of the variable Swap in this algorithm. [2]
3. (c) Explain why the value of Last is reduced by 1 after each pass. [1]

1. (a) The array Sales[1:30] holds the daily sales, in rupees, of a bakery in Lahore for one month. Write pseudocode to:- calculate the total sales for the month- count the number of days on which sales were more than 50000- output the total, the count and the average daily sales. [6]

1. (a) The array Cities[1:10] holds the names of 10 cities. Write pseudocode for an efficient bubble sort that puts the names into alphabetical order. The sort must stop as soon as a pass is completed with no swaps. [6]

1. (a) State the four stages of the program development life cycle, in order. [2]
2. (b) Give one task that is carried out during the analysis stage. [1]

1. (a) A school canteen in Rawalpindi wants a program that lets students order lunch on a tablet. Decompose the system by identifying one input, one process, one output and one item of storage it needs. [4]
2. (b) Name one design method that could show how the canteen system is broken down into sub-systems. [1]

1. (a) A team is writing software for a parcel-delivery company. Explain why the team decomposes the problem into sub-systems before coding. [3]
2. (b) The team uses a structure diagram, a flowchart and pseudocode during design. Describe what each of these shows. [3]

1. (a) A program for a minibus booking system accepts the number of passengers as a whole number from 1 to 18 inclusive. Give one example of each type of test data.(i) Normal data(ii) Extreme data(iii) Abnormal data [3]
2. (b) Give the two boundary values tested at the upper end of the range. [2]

1. (a) A program checks that a new password is between 8 and 20 characters long, inclusive. Complete a test plan by giving, for each type of test data, an example password length and the expected result.(i) Normal(ii) Extreme(iii) Boundary (the rejected value at the lower end)(iv) Abnormal [4]

1. (a) A weather station program accepts temperatures from −10.0 °C to 45.0 °C inclusive, given to one decimal place. State the type of test data (normal, abnormal, extreme or boundary) for each value and whether it should be accepted or rejected.(i) 23.4(ii) −10.0(iii) 45.1(iv) hot [4]
2. (b) Explain why boundary testing uses values on both sides of each limit. [1]