Administrivia- IntroductionStaffLinda G. ShapiroWeb PageOffice HoursCSE 373 E-mail ListComputer LabTextbookGradingClass OverviewGoalCourse TopicsReadingData Structures: What?Data Structures: Why?TerminologyAlgorithm Analysis: Why?Iterative Algorithm for SumProgramming via RecursionPseudocodeProof by InductionProgram Correctness by InductionAlgorithms vs ProgramsAdministrivia- IntroductionCSE 373Data Structures12/26/03 CSE 373 WI 04- Introduction 2Staff•Instructor›Linda G. Shapiro, [email protected]•TA’s›Gaurav Bhaya, [email protected]›Matthew Milcic, [email protected]/26/03 CSE 373 WI 04- Introduction 3Linda G. Shapiro• Professor of Computer Science and Engineering• Professor of Electrical Engineering• Adjunct Professor of Medical Education and Biomedical Informatics• Research: Computer Vision & Content-Based Image Retrieval12/26/03 CSE 373 WI 04- Introduction 4Web Page•All info is on the web page for CSE 373›http://www.cs.washington.edu/373›also known as•http://www.cs.washington.edu/education/courses/373/04wi12/26/03 CSE 373 WI 04- Introduction 5Office Hours•Linda Shapiro – 634 CSE (Allen Center)›MWF 9:30-10:30 or by appointment •Gaurav Bhaya – to be announced•Matthew Milcic – to be announced•Third TA - to be announced12/26/03 CSE 373 WI 04- Introduction 6CSE 373 E-mail List•Subscribe by going to the class web page.•E-mail list is used for posting announcements by instructor and TAs.•It is your responsibility to subscribe. It will turn out to be very helpful for assignments hints, corrections etc.12/26/03 CSE 373 WI 04- Introduction 7Computer Lab•Math Sciences Computer Center›http://www.ms.washington.edu/•Project can be done in Java or C++›We ordered most of the texts in Java, but there should be some in C++.12/26/03 CSE 373 WI 04- Introduction 8Textbook •Data Structures and Algorithm Analysis in Java (or in C++), by Weiss•See Web page (syllabus) for errata and source code12/26/03 CSE 373 WI 04- Introduction 9Grading•Assignments and programming projects 50%•Midterm 20%›Approximately Feb. 13 (not definite yet)•Final 30%›2:30-4:20 p.m. Wednesday, March 17, 200412/26/03 CSE 373 WI 04- Introduction 10Class Overview•Introduction to many of the basic data structures used in computer software›Understand the data structures›Analyze the algorithms that use them›Know when to apply them•Practice design and analysis of data structures.•Practice using these data structures by writing programs.•Data structures are the plumbing and wiring of programs.12/26/03 CSE 373 WI 04- Introduction 11Goal•You will understand›what the tools are for storing and processing common data types›which tools are appropriate for which need•So that you will be able to›make good design choices as a developer, project manager, or system customer12/26/03 CSE 373 WI 04- Introduction 12Course Topics•Introduction to Algorithm Analysis•Lists, Stacks, Queues•Search Algorithms and Trees•Hashing and Heaps•Sorting•Disjoint Sets•Graph Algorithms12/26/03 CSE 373 WI 04- Introduction 13Reading•Chapters 1 and 2, Data Structures and Algorithm Analysis in Java/C++, by Weiss›Very important sections:•Section 1.2.5 on proofs•Section 1.3 on recursion›Most of Chapter 2 will be seen in Lecture 412/26/03 CSE 373 WI 04- Introduction 14Data Structures: What?•Need to organize program data according to problem being solved•Abstract Data Type (ADT) - A data object and a set of operations for manipulating it›List ADT with operations insert and delete›Stack ADT with operations push and pop•Note similarity to Java classes›private data structure and public methods12/26/03 CSE 373 WI 04- Introduction 15Data Structures: Why?•Program design depends crucially on how data is structured for use by the program›Implementation of some operations may become easier or harder›Speed of program may dramatically decrease or increase›Memory used may increase or decrease›Debugging may be become easier or harder12/26/03 CSE 373 WI 04- Introduction 16Terminology•Abstract Data Type (ADT)›Mathematical description of an object with set of operations on the object. Useful building block.•Algorithm›A high level, language independent, description of a step-by-step process•Data structure›A specific family of algorithms for implementing an abstract data type.•Implementation of data structure›A specific implementation in a specific language12/26/03 CSE 373 WI 04- Introduction 17Algorithm Analysis: Why?•Correctness: ›Does the algorithm do what is intended.•Performance:›What is the running time of the algorithm.›How much storage does it consume.•Different algorithms may correctly solve a given task›Which should I use?12/26/03 CSE 373 WI 04- Introduction 18Iterative Algorithm for Sum•Find the sum of the first num integers stored in an array v. sum(v[ ]: integer array, num: integer): integer{ temp_sum: integer ; temp_sum := 0; for i = 0 to num – 1 do temp_sum := v[i] + temp_sum; return temp_sum;}Note the use of pseudocode12/26/03 CSE 373 WI 04- Introduction 19Programming via Recursion•Write a recursive function to find the sum of the first num integers stored in array v.sum (v[ ]: integer array, num: integer): integer { if num = 0 then return 0 else return v[num-1] + sum(v,num-1);}base caserecursivecase12/26/03 CSE 373 WI 04- Introduction 20Pseudocode•In the lectures algorithms will be presented in pseudocode.›This is very common in the computer science literature›Pseudocode is usually easily translated to real code.›This is programming language independent•Pseudocode should also be used for homework12/26/03 CSE 373 WI 04- Introduction 21Proof by Induction•Basis Step: The algorithm is correct for the base case (e.g. n=0) by inspection.•Inductive Hypothesis (n=k): Assume that the algorithm works correctly for the first k cases, for any k.•Inductive Step (n=k+1): Given the hypothesis above, show that the k+1 case will be calculated correctly.12/26/03 CSE 373 WI 04- Introduction 22Program Correctness by Induction•Basis Step: sum(v,0) = 0. •Inductive Hypothesis (n=k): Assume sum(v,k) correctly returns sum of first k elements of v, i.e. v[0]+v[1]+…+v[k-1]•Inductive Step (n=k+1): sum(v,n) returns v[k]+sum(v,k) which is the sum of first k+1 elements of v. 12/26/03 CSE 373 WI 04- Introduction 23Algorithms vs