Systematic Approach To Problem Solving Aqa

• When designing algorithms there are two main tools that can be used to describe them:

  • Pseudocode

  • Flowcharts

Systemic Approach

What is a systematic approach to problem solving?

• A systematic approach means being able to take a logical approach and use algorithmic thinking to solve a problem

• Some examples of systematic approaches include:

  • Solving a word search puzzle

  • Finding an item within a list

• A good example of a systematic approach would be a program used to find a username and the matching password in a 2D list

• In the example below, the 2D list has column 0 which stores the username and column 1 which stores the password

• To iterate through the list, an algorithm would have to take a systematic approach to look for the username entered by the user and then look in the column to the immediate right to find the password for that user

users = [["Dave", "Un1corn$"],["George", "B@tman#1"],["Elizabeth", "Coffee!!"],["Henry", "Walking&123"]] # Ask the user for a name to search for
name_to_find = input("Enter a name to find: ") # Search for the name in the first column of the list of users
found = False
for i in range(len(users)): if name_to_find == users[i][0]: found = True password_to_check = input("Enter the password: ") if password_to_check == users[i][1]: print("Password correct. Access granted.") break else: print("Incorrect password. Access denied.") break if found == False: print("Name not found.")

Pseudocode

What is pseudocode?

• Pseudocode is a text based tool that uses short English words/statements to describe an algorithm

• Pseudocode is more structured than writing sentences in English, but is very flexible

Example

• A casino would like a program that asks users to enter an age, if they are 18 or over they can enter the site, if not then they are given a suitable message

Age ← USERINPUT
IF age >= 18 THEN OUTPUT("Welcome to the site")
ELSE OUTPUT("Sorry, this site is for users 18 and over")
ENDIF

• The casino would like the algorithm refined so that the user also enter their first name and this is used to greet the user when they access the site

Fname ← USERINPUT
Age ← USERINPUT
IF age >= 18 THEN OUTPUT("Welcome to the site" + fname)
ELSE OUTPUT("Sorry, this site is for users 18 and over")
ENDIF

What are the AQA pseudocode rules?

• AQA use a standard style for pseudocode which has been around for many years and that is seen in AQA based exams to describe algorithms

• Pseudocode has no official syntax so to keep exams consistent AQA have stuck with a common and well-used format

Examples

Program Code

• Program code, unlike the generic pseudocode, is specific to a programming language

• The accepted languages you can answer questions in are:

  • C#

  • Python (version 3)

  • VB.NET (opens in a new tab)

• Exam questions will indicate the form of response expected, for example, pseudocode, program code or a flowchart

Flowcharts

What is a flowchart?

• Flowcharts are a visual tool that uses shapes to represent different functions to describe an algorithm

• Flowcharts show the data that is input and output, the processes that take place and any decisions or repetition

• Lines are used to show the flow of control

Example