Big Ideas in Computer Science Divide, Conquer, & Glue CS111 - PDF document

Big Ideas in Computer Science • Divide, Conquer, & Glue CS111 Wrap-Up • Abstraction • Modularity X - 1 X - 2 Divide, Conquer, & Glue Abstraction • Suppose you have a problem P and you want its solution S • Abstraction is a way of capturing common patterns • For example, once you learn how to drive, you can drive any car - P they all have common features such as steering, gas, and breaking. Once you learn these, you can use any car. Divide into subproblems • Of course, every car is different - they have different engines and P 1 P 2 P 3 P 4 breaking systems. But I don’t need to understand the details of the Conquer subproblems different engines to drive different cars (which is good, because I S 1 S 2 S 3 S 4 don’t have a clue!) Glue (combine) the • But I can drive, because I understand the interface (the breaks, the subproblems into solution gas, the steering) S X - 3 X - 4 Modularity A CS111 Retrospective • Modularity occurs when components are designed in a PS0: Web form standard manner such that they can be put together in a mix and match way – legos – computer peripherals – phone jacks – couches • If we have abstraction AND modularity, we can build bigger things out of smaller things (a very powerful idea) X - 5 X - 6

A CS111 Retrospective A CS111 Retrospective PS1: Writing simple Java code, reading PS2: Writing methods, modularity, applets, local contracts, extending someone else’s code variables, expression and assignment statements X - 7 X - 8 A CS111 Retrospective A CS111 Retrospective PS3: More methods, methods with parameters, PS4: Conditionals, good programming style, methods which return values, abstraction objects and classes X - 9 X - 10 A CS111 Retrospective A CS111 Retrospective PS5: Recursion, JEMs, inheritance PS6: More recursion, recursive methods that return values X - 11 X - 12

A CS111 Retrospective A CS111 Retrospective PS7: Lists, strings, recursive list methods, PS8: Iteration (while and for loops), lists of lists applications, linear collection data structures X - 13 X - 14 A CS111 Retrospective PS9: Arrays, data abstraction, declaring Java classes, using Java graphics, working in pairs X - 15