Algorithms (Cambridge International IGCSE Computer Science): Exam Questions

Write the pseudocode statement that would output the average calculated in line 13 of the algorithm rounded to one decimal place.

Describe what the algorithm represented by the flowchart in Fig. 1 is doing.

Fig.1

The pseudocode algorithm shown has been written by a teacher to enter marks for the students in her class and then to apply some simple processing.

Count ← 0 REPEAT INPUT Score[Count] IF Score[Count] >= 70 THEN Grade[Count] ← "A" ELSE IF Score[Count] >= 60 THEN Grade[Count] ← "B" ELSE IF Score[Count] >= 50 THEN Grade[Count] ← "C" ELSE IF Score[Count] >= 40 THEN Grade[Count] ← "D" ELSE IF Score[Count] >= 30 THEN Grade[Count] ← "E" ELSE Grade[Count] ← "F" ENDIF ENDIF ENDIF ENDIF ENDIF Count ← Count + 1 UNTIL Count = 30

Describe what happens in this algorithm.

B ← FALSE

INPUT Num

FOR Counter ← 1 TO 12

IF A[Counter] = Num

THEN

B ← TRUE

ENDIF

NEXT Counter

Identify the purpose of the algorithm.

The flowchart shows an algorithm that should allow 60 test results to be entered into the variable Score.

Each test result is checked to see if it is 50 or more. If it is, the test result is assigned to the Pass array. Otherwise, it is assigned to the Fail array.

Complete this flowchart

Write a pseudocode routine that will check that each test result entered into the algorithm is between 0 and 100 inclusive.

The pseudocode represents an algorithm.

The pre-defined function DIV gives the value of the result of integer division. For example, Y = 9 DIV 4 gives the value Y = 2

The pre-defined function MOD gives the value of the remainder of integer division. For example, R = 9 MOD 4 gives the value R = 1

First ← 0 Last ← 0 INPUT Limit FOR Counter ← 1 TO Limit INPUT Value IF Value >= 100 THEN IF Value < 1000 THEN First ← Value DIV 100 Last ← Value MOD 10 IF First = Last THEN OUTPUT Value ENDIF ENDIF ENDIF NEXT Counter

Describe the purpose of the algorithm.

This algorithm checks the temperature of hot food being served to customers.

State how the final output from the algorithm could be improved.

Identify the process in the algorithm that is not required.

This flowchart represents an algorithm.

Describe what the algorithm represented by the flowchart is doing.

The variables P and Q are used to store data in a program. P stores a string. Q stores a character.

Give the value of Position after the algorithm has been executed with the data in the below question.

Write pseudocode statements to declare the variables P and Q, store "The world" in P and store 'W' in Q

This pseudocode algorithm is intended to allow, at random, between 1 and 20 values to be entered and totalled.

The total and average of the entered values are output at the end of the algorithm.

Identify the line numbers of four errors in the pseudocode and suggest corrections

Describe the purpose of the algorithm.

The variables X, Y and Z are used to store data in a program:

• X stores a string
• Y stores a position in the string (e.g. 2)
• Z stores the number of characters in the string.

The function LENGTH(X) finds the length of a string X.

The function SUBSTRING(X,Y,Z) finds a substring of X starting at position Y and Z characters long. The first character in X is in position 1.

Write pseudocode statements to:

• store the string "Programming is fun" in X
• find the length of the string and output it
• extract the word fun from the string and output it.

The one-dimensional (1D) array StudentName[] contains the names of students in a class. The two-dimensional (2D) array StudentMark[] contains the mark for each subject, for each student. The position of each student’s data in the two arrays is the same, for example, the student in position 10 in StudentName[] and StudentMark[] is the same.

The variable ClassSize contains the number of students in the class. The variable SubjectNo contains the number of subjects studied. All students study the same number of subjects.

The arrays and variables have already been set up and the data stored.

Students are awarded a grade based on their average mark.

Write a program that meets the following requirements:

• calculates the combined total mark for each student for all their subjects

• calculates the average mark for each student for all their subjects, rounded to the nearest whole number

• outputs for each student:

  • name
  • combined total mark
  • average mark
  • grade awarded

• calculates, stores and outputs the number of distinctions, merits, passes and fails for the whole class.

You must use pseudocode or program code and add comments to explain how your code works.

You do not need to initialise the data in the array.

Draw a flowchart for an algorithm to:

• allow numbers to be input
• ignore any numbers that are negative
• count how many numbers are positive
• output the count of positive numbers when zero is input and end the algorithm.

Extract:

allow numbers to be input ignore any numbers that are negative count how many numbers are positive output the count of positive numbers when zero is input and end the algorithm.

Explain the changes you will make to your algorithm to also count the negative numbers.

Rewrite this pseudocode algorithm using a WHILE … DO … ENDWHILE loop.

B ← FALSE INPUT Num FOR Counter ← 1 TO 12 IF A[Counter] = Num THEN B ← TRUE ENDIF NEXT Counter

The names of patients are stored in the one-dimensional (1D) array Patient[] of type string. A separate two-dimensional (2D) array Readings[] stores the latest data recorded about each patient. The array already contains the readings taken by a nurse for each patient:

• temperature measured to one decimal place
• pulse rate, a whole number.

Temperature readings should be in the range 31.6 to 37.2 inclusive. Pulse readings should be in the range 55.0 to 100.0 inclusive.

The hospital number given to the patient is used for the index on both arrays, this is a value between 1 and 1000 inclusive.

When the data for a patient is checked a warning is given if any of the readings are out of range. If both readings are out of range, then a severe warning is given.

Write a procedure, using pseudocode or program code, that meets the following requirements:

• takes the hospital number as a parameter

• checks if the number is valid

• outputs an error message and exits the procedure if the number is not valid

• if the hospital number is valid:

  • output the patient’s name
  • output ‘Normal readings’ if both the readings are within range
  • output ‘Warning’ and the name of the reading e.g. ‘Pulse’ if one reading is out of range
  • output ‘Severe warning’ and the names of the two readings ‘Pulse and temperature’ if both readings are out of range
  • exits the procedure.

You must use pseudocode or program code and add comments to explain how your code works.

You do not need to initialise the data in the arrays.

An algorithm has been written in pseudocode to allow some numbers to be input. All the positive numbers that are input are totalled and this total is output at the end. An input of 0 stops the algorithm.

Describe how you could change the corrected algorithm to record and output how many positive numbers have been included in the final total.

You do not need to rewrite the algorithm.