2.1 - Elements of computational thinking Flashcards
What is computational thinking?
Ability to think logically about a problem + apply techniques for solving it.
Related to skill of designing algorithms -> turned into computer program
What is abstraction?
- Removing unnecessary details from the problem + focusing on the main part or one part at a specific time.
- Seperating the logical & physical aspects of a problem.
- e.g. Physical = Driver for a car, Logical = Mechanic for a car.
What can you create with abstraction?
- Devising a model that represents reality & removing details that don’t contibute to the central characteristics of the problem. E.g. London underground map.
How do you solve a problem using abstraction?
- Can build a model of a real world object/Phenomenun may be used to help solve a particular problem.
- Decide what details are relevent to the problem + discard everything else.
- Algorithms + data structures can be designed to solve the problem.
- Algorithm is then implemented in program code + executed.
- e.g. Financial model - calculates likely profit of coffee shop from availible data.
What is an abstract model?
A computer program shown by a simple diagram. Details are added until it is transformed into a computer program.
What are the 3 parts of a abstract model?
- Input = information relevent to the problem. e.g. could be passed as parameter to a subroutine.
- COMPUTATIONAL PROBELM.
- Output = Solution to the problem. e.g. could be passed back from a subroutine.
What are the 2 challenges to creating a solution?
- Algorithm must be CORRECT - must work for all possible inputs.
- Algorithm must be EFFICIENT - Often problems involve lots of data so must find most efficient algorithm.
What should you do with inputs & outputs?
- Document / Identify them so that there is no ambiguity in what must be supplied to the sub-procedure, and what is returned.
What is Decomposition?
Breaking a problem into a number of sub problems, so each sub problem accomplished an identifiable task.
Sub programs can be further divided.
What are the 4 features of structured programming?
- It aims to improve the clarity and quality of a program.
- Modularization for program structure + organisation
- Structured code for the individual models; code uses basic constructs of sequence, selection & iteration.
- Recursion
What is modularization?
(In the context of structured programming)
Breaking the program into subroutines.
What is the Top-down model technique?
- Program divided into sub-procedures or modules which are called from the main program.
- Sub-procedurs can be broken down further into smaller sub tasks (Smallest part can perform a single function).
- Represented in a heirachy chart to show overall program structure.
How is a heirachy chart executed?
Left to right until the lowest component. (Will go down the tree back up and then continue along)
What are the 8 benefits of Modularization?
- large programs broken down into subtasks/subroutines = easier to program + manage.
- Each subroutine can be tested individually.
- Modules become reusable.
- Frequently used modules can be saved in a library & used by other programs.
- Several programmers can simultaneously work on different modules, shortening developmentive time.
- easier to find errors in small modules so program = more reliable + less errors.
- Programs take less time to test + debug.
- Programs are easier to maintain.
What are the 2 features of an easy to maintain program?
- Well organised, easy to find and self contained modules.
- New features added by adding new modules.
What are the 5 features of good programming practice?
- Meaningful identifiers.
- Define + document inputs/outputs/preconditions for each sub-procedure.
- Lots of meaningful comments within the program.
- At bottom level, each sub procedure should perform a single task.
- Keep each sub-procedure self contained by passing parameters + local variables.
What should you do once you have identified the components of the program?
Plan the overall method of the solution; involves writing procedures/functions + passing parameters.
e.g. car dealer wants program to help potential customer select options for a new car.
What are the 3 advantages of preconditions?
- Makes program components reusable.
- Cuts out unnecessary checks.
- Makes programs easier to debug.
What are the 5 typical standards for reusable models?
- Inputs + Outputs + preconditions should be documented in standard format. (explaining what the module does who it was written by, date is was)
- Variable identifiers should conform to standard convention.
- All variables should be local to the module.
- Explanations of certain sections of code should be included when necessary.
- No module should exceed one page of code.
Why are the 3 reasons for a program module to be reusable?
- Easier to use for other programmers.
- Can be added to a library + imported whenever needed.
- In a large project - saves time in writing + testing functions which have already been written, debugged and tested.
What is another aspect of thinking ahead?
Anticipating what the user may want to do next.
e.g. impact menu design in software package with several levels of menu.
What is caching?
A temporary storage of data and instructions.
Last few instructions of a program to be executed, the result of an earlier computation, or data used may be stored in memory so they can be revied quickly.
What is web caching?
Storing HTML pages + images recently looked at, is often asked.
What are the 3 advantages to caching?
- Faster access to cached resources.
- Saving on costly use of bandwidth.
- Reduced load on web services in client-server environment.
