8 Arrays and Important Algorithms

Question 1

What is an array?

Answer 1

• Collection of variables of the same data type
• Referred to by a single name (identifier)
• Each element is accessed by an index (position)
• Often called a data structure

Question 2

What are the advantages of an array?

Answer 2

+ can store multiple values under a single identifier
+ reduces the number of variables
+ can use iteration to loop through an array
+ allows for more efficient programming

Question 3

Write an algorithm that searches through an array of integers named nums to find the highest value and the average of all of the numbers stored. The array stores 100 numbers.

Your program should then output the highest value and average. You can assume all variables have been declared already

Answer 3

total ← 0
highest ← -999999
average ← 0

FOR i ← 1 TO 100 STEP 1
    total ← total + nums[i]
 
    IF nums[i] > highest THEN
        highest ← nums[i]
    ENDIF
NEXT i
 
average ← total / 100

OUTPUT "Average", average
OUTPUT "Highest", highest

Question 4

Write an algorithm that asks the user to enter 10 names and stores them into an array called names.

It should then output the names in reverse order

Answer 4

DECLARE names : ARRAY[1:10] OF STRING
 
OUTPUT “Enter 10 names:”

// Store each name input into the array
FOR i ← 1 TO 10 STEP 1
    INPUT names[i]
NEXT i

// Loop through the array and output the names in reverse 
FOR i ← 10 TO 1 STEP -1
    OUTPUT reverse[i], " "
NEXT i

Question 5

Declare an array to store 30 names

Answer 5

DECLARE names : ARRAY[1:30] OF STRING

Question 6

Declare an array to store 100 ages

Answer 6

DECLARE ages : ARRAY[1:100] OF INTEGER

Question 7

Declare a 2D array (called results) that has 10 rows and 8 columns of whole numbers

Answer 7

DECLARE results : ARRAY[1:10, 1:8] OF INTEGER

Question 8

A 2D array (results) has been used to store the exam results for 10 students. Each row is a set of student results. 8 results are stored for each student (each column stores the subject result). There is also an that array stores the student names for each row of results in order.

Write an algorithm in pseudocode to output the results for each student.

DECLARE results : ARRAY[1:10, 1:8] OF INTEGER
DECLARE names : ARRAY[1:10] OF STRING

Answer 8

FOR studentCount <- 1 TO 10 STEP 1
    OUTPUT names[studentCount]
		
	FOR subjectCount <- 1 TO 8 STEP 1
	    OUTPUT results[studentCount, subjectCount]
	NEXT i
NEXT i

Question 9

Write an algorithm that allows the user to input an integer. It should then search through an array called AList and output the position of the entered number in the array. If the value entered is not in the array it should output “Item not found”

Answer 9

Question 10

Write a bubble sort algorithm that sorts an array of integers called AList into ascending order.

Answer 10