2.1 ALGORITHMS

2.1 ALGORITHMS

1. Computational thinking

   • What is Computational Thinking?
     • Computational thinking is a way of understanding complex problems in order to form a solution that can be implemented by either a computer, a human or a combination of both.
       • There are 3 key elements to computational thinking
         • Algorithmic thinking
           • Identifying logical steps from the problem to a solution to produce a reusable algorithm
           • There are 3 main building blocks of all algorithms
             • Sequence
               • A series of steps that are to be completed one-by-one
             • Selection
               • Steps that only occur if a certain condition is met
             • Iteration
               • Steps that repeat, either for a fixed number of times or until a condition is met
         • Abstraction
           • Removing details that are not relevant to solving the problem
           • An example of abstraction would be the London underground map
         • Decomposition
           • Breaking down a problem into smaller pieces
           • Structure charts are examples of Decomposition

2. Producing algorithms using pseudocode and flow diagrams

   • What is pseudocode?
     • Pseudocode is a way to write out algorithms using code-like statements
     • It is not an actual programming language
     • There is no "correct" way to write it
     • It is used to plan algorithms, focussing on the logic and steps rather than language-specific syntax
   • OCR's guide to pseudocode
     • Whilst it is true that there is no "correct" way to write pseudocode, OCR will alway present pseudocode in a consistent way in exam papers.
     • You should read through the OCR guide to pseudocode to ensure that you are familiar with how they will represent each of the Programming Techniques covered on the course using pseudocode.
   • Flow Charts
     • Flow diagrams visually represent the steps that make an algorithm.
     • A standard set of shapes are used to represent different types of step, such as running a sub-process or taking one path or another depending on a condition being met.
     • The arrows in a flow diagram represent the flow of control through the algorithm.