1. Chapters 7, 8, & 9 Quiz 3 Review 1

2. 2 Algorithms Algorithm A set of unambiguous instructions for solving a problem or subproblem in a finite amount of time using a finite amount of data Abstract Step An algorithmic step containing unspecified details Concrete Step An algorithm step in which all details are specified

3. 3 Developing an Algorithm Two methodologies used to develop computer solutions to a problem –Top-down design focuses on the tasks to be done –Object-oriented design focuses on the data involved in the solution (We will discuss this design in Ch. 9)

4. 4 Summary of Methodology Analyze the Problem Understand the problem!! Develop a plan of attack List the Main Tasks (becomes Main Module) Restate problem as a list of tasks (modules) Give each task a name Write the Remaining Modules Restate each abstract module as a list of tasks Give each task a name Re-sequence and Revise as Necessary Process ends when all steps (modules) are concrete

5. 5 Control Structures Control structure An instruction that determines the order in which other instructions in a program are executed

6. 6 Selection Statements Flow of control of if statement

7. 7 Looping Statements Flow of control of while statement

8. Arrays As data is being read into an array, a counter is updated so that we always know how many data items were stored If the array is called list, we are working with list[0] to list[length-1]or list[0]..list[length-1] 8

9. 9 Sorted Arrays The values stored in an array have unique keys of a type for which the relational operators are defined Sorting rearranges the elements into either ascending or descending order within the array A sorted array is one in which the elements are in order

10. 10 Binary Search Sequential search Search begins at the beginning of the list and continues until the item is found or the entire list has been searched Binary search (list must be sorted) Search begins at the middle and finds the item or eliminates half of the unexamined items; process is repeated on the half where the item might be Say that again…

11. 11 Subprogram Statements

12. 12 Recursion The ability of a subprogram to call itself Base case The case to which we have an answer General case The case that expresses the solution in terms of a call to itself with a smaller version of the problem

13. 13 Recursion For example, the factorial of a number is defined as the number times the product of all the numbers between itself and 0: N! = N * (N  1)! Base case Factorial(0) = 1 (0! is 1) General Case Factorial(N) = N * Factorial(N-1)

14. CHAPTER 8 14

15. 15 Logical Implementations Two logical implementations of containers: Array-based implementation Objects in the container are kept in an array Linked-based implementation Objects in the container are not kept physically together, but each item tells you where to go to get the next one in the structure Did you ever play treasure hunt, a game in which each clue told you where to go to get the next clue?

16. 16 Stacks Stack An abstract data type in which accesses are made at only one end –LIFO, which stands for Last In First Out –The insert is called Push and the delete is called Pop Name three everyday structures that are stacks

17. 17 Queues Queue An abstract data type in which items are entered at one end and removed from the other end –FIFO, for First In First Out –No standard queue terminology Enqueue, Enque, Enq, Enter, and Insert are used for the insertion operation Dequeue, Deque, Deq, Delete, and Remove are used for the deletion operation. Name three everyday structures that are queues

18. 18 Stacks and Queues Stack and queue visualized as linked structures

19. 19 Linked Implementations

20. 20 Trees Binary tree A linked container with a unique starting node called the root, in which each node is capable of having two child nodes, and in which a unique path (series of nodes) exists from the root to every other node A picture is worth a thousands words…

21. 21 Binary Search Trees Binary search tree (BST) A binary tree (shape property) that has the (semantic) property that characterizes the values in a node of a tree: The value in any node is greater than the value in any node in its left subtree and less than the value in any node in its right subtree

22. 22 Binary Search Tree Figure 8.7 A binary search tree Each node is the root of a subtree made up of its left and right children Prove that this tree is a BST

23. 23 Graphs Graph A data structure that consists of a set of nodes (called vertices) and a set of edges that relate the nodes to each other Undirected graph A graph in which the edges have no direction Directed graph (Digraph) A graph in which each edge is directed from one vertex to another (or the same) vertex

24. 24 Graphs Figure 8.10 Examples of graphs

25. CHAPTER 9 25

26. 26 Object-Oriented Design Object-oriented Design A problem-solving methodology that produces a solution to a problem in terms of self-contained entities called objects Object A thing or entity that makes sense within the context of the problem For example, a student, a car, time, date

27. Translation Process A program written in a high-level language must be translated into machine code The machine code is then executed Compilers and Interpreters are software tools employed to help with the translation process 27

28. 28 Compilers High-level language A language that provides a richer (more English-like) set of instructions Compiler A program that translates a high-level language program into machine code

29. 29 Compilers Figure 9.2 Compilation process How does this differ from the assembly process?

30. 30 Interpreters Interpreter A translating program that translates and executes the statements in sequence –Assembler or compiler produce machine code as output, which is then executed in a separate step –An interpreter translates a statement and then immediately executes the statement –Interpreters can be viewed as simulators

31. 31 Java Introduced in 1996 and became instantly popular Portability was of primary importance Java is compiled into a standard machine language called Bytecode A software interpreter called the JVM (Java Virtual Machine) takes the Bytecode program and executes it

32. 32 Portability The ability of a program to be run on different machines Compiler portability A program in a standardized language can be compiled and run on any machine that has the appropriate compiler Bytecode portability A program translated into Bytecode can be run on any machine that has a JVM Do you understand the difference?

33. 33 Asynchronous Processing Asynchronous processing Not synchronized with the program's action –Clicking has become a major form of input to the computer –Mouse clicking is not within the sequence of the program –A user can click a mouse at any time during the execution of a program