Section 2 Chapter 9 - Writing and Interpreting Diagrams

Question 1

Properties of a good algorithm (5)

Answer 1

• Clear and precisely stated steps that produce a correct output
• Should allow for invalid inputs
• Must always terminate at some point
• Execute efficiently in as few steps as possible
• It should be designed in a way that is understandable and can be easily modifed

Question 2

Common types of algorithm (4)

Answer 2

• Internet related
• Route finding
• Compression
• Encryption

Question 3

Internet related algorithm

Answer 3

Can be used to manage and manipulate huge amounts of data stored on the Internet e.g. a search engine

Question 4

Route finding algorithm

Answer 4

Finds the shortest route between two points for instance the fastest driving route or the best route to transmit packets over a network

Question 5

Compression algorithm

Answer 5

Used to reduce the file space taken up by a file while still ideally retaining most of the relevant information

Question 6

Encryption algorithm

Answer 6

Hides information so that it can only be read by the sender and receiver and not a third party

Question 7

Binary search algorithm

Answer 7

1 - Check the value in the middle
2 - If larger than target, delete the second half of the list, if smaller delete the first half of the list
3 - Repeat steps 1 and 2 until the target is found

Question 8

Sorting algorithm

Answer 8

Puts an unordered list in order

Question 9

Bubble sort algorithm

Answer 9

1 - Loop through the array swapping each pair of values that are in the wrong order
2 - Repeat (length of list) time, reducing the number of elements to be examined by 1 each time

Question 10

Tips for interpreting algorithms (4)

Answer 10

• Read the comments
• Look at the variable names
• Follow the steps in the program
• Try a “dry run” with some test data