A-level Computing/AQA/Problem Solving, Programming, Data Representation and Practical Exercise/Skeleton code/2013 Exam/Section B

=Section B Introduction= This section will ask you questions that you will have to find programming solutions to. The past exam papers have always provided a strict program specification in the form of variable names and pseudocode. It is very likely that a problem will be set around the theme of cryptography but different to the skeleton code in some way. You should be able to interpret pseudocode, structured english, structure charts, stepwise refinement tables and decision tables. Any of these techniques could be used to communicate an algorithm to be coded.

Practice questions
Obviously all the past papers from AQA have good section B questions that you should attempt. Here are some around this year's theme...

Numeric Caesar Cipher
(a) Write a program that encrypts a number sequence using the same principle as the Caesar Cipher. (b) Test your program using a key= 6 and the number sequence 0123456789

Character Frequency
Using the average frequency that characters appear is one way to "crack" many simple ciphers. You can learn more about this here: http://en.wikipedia.org/wiki/Letter_frequency.

Write a program that counts the number of times each character appears in some inputted text. It should output a list of characters with the number of times each appears.

(pseudo-code to follow)

Another question....