2.1 | Algorithms | 2.1.1 - 2.1.3

2.1 | Algorithms | 2.1.1 - 2.1.3

1. 2.1.1

   • Abstraction
     • Abstraction is a technique that simplifies a problem by removing unnecessary detail so that you can focus on the important parts that are relevant to the problem.
     • Examples of abstraction
       • Maps are a classic example of abstraction. They leave out many details in order to focus on the important information, such as roads and landmarks.
       • Money is an abstract concept. Money has no real value (it's just a piece of paper!), but it represents the value of goods and services.
   • Decomposition
     • Decomposition means breaking a complex problem into smaller, more manageable sub-problems.
       • Each smaller part can then be solved individually, before all the sub-solutions are combined to solve the original problem.
     • Advantages of decomposition
       • Decomposition allows large teams to each take a part of a problem and work on it.
         • Decomposition allows seemingly impossible problems to be solved by splitting them into simple tasks.
     • Structure Charts
       • Structure charts are used to visually represent breaking a large problem down into the smaller parts that make it up.
         • Each box represents a smaller problem to be solved.
           • Lines show which bigger problem the box is a part of.
   • Algorithmic Thinking
     • Algorithmic thinking is a way of solving problems by producing algorithms.
     • Algorithms
       • An algorithm is a reusable set of instructions (a series of steps) to solve a given problem.
         • We use algorithms all the time. For example, consider the steps that you take to: make a cup of tea or get dressed.
     • Writing an algorithm
       • Algorithms can be written as a set of numbered steps to follow.
         • A non-technical example of a written algorithm is a cooking recipe.
           • In computing, we often represent algorithms using pseudocode or flow diagrams.

2. 2.1.2

   • Pseudocode
     • Pseudocode is a way to write out algorithms using code-like statements.
       • It is intended to be very readable, and easy to understand.
     • Purpose of pseudocode
       • Pseudocode is used to plan algorithms, focusing on the logic and steps rather than language-specific syntax.
   • Flow Diagrams
     • Pseudocode is used to plan algorithms, focusing on the logic and steps rather than language-specific syntax.
     • A standard set of shapes are used to represent different types of step.
       • Arrows represent the flow of control, or what to execute next.
     • Standard Shapes
       • An oval is used for the start and end of a program.
       • A rectangle is used to represent a process.
       • A parallelogram is used to represent an input or an output.
       • A diamond is used to represent a decision.
         • A decision has two labelled arrows coming out of it.
           • The 'Yes' arrow is followed if the condition in the diamond was true, otherwise the 'No' arrow is followed.