CS 315 Data Structures B. Ravikumar Office: 116 I Darwin Hall Phone: 664 3335

1. CS 315 Data Structures B. Ravikumar Office: 116 I Darwin Hall Phone: 664 3335 E-mail: ravi93@gmail.edu Course Web site: http://ravi.cs.sonoma.edu/cs315sp09

2. Textbook for the course: Data Structures and Algorithm Analysis in C++ by Mark Allen Weiss Class time Lecture: T Th 10:45 to 12 noon, Darwin Hall 102 Lab: F 9 to 11:50 AM, Darwin Hall # 25

3. Data Structures – informal definition • How to store data sets in memory so that the computation(s) can be solved easily, efficiently etc. • Some typical issues: • preprocessing vs. updating • trade-offs between operations • interaction between algorithm and data structure

4. Course Goals • Learn to use fundamental data structures: • arrays, linked lists, stacks and queues • hash table • priority queue – binary heap and others • binary trees, binary search trees, AVL trees • quad-trees, skip-lists • Improve your skill in programming in c++ • recursion, classes, algorithm implementation • design solutions using different data structures

5. Course Goals • Analytical and experimental analysis • quantitative reasoning about the performance of algorithms (time, storage, network, bandwidth etc.) • comparing different data structures • Applications • image storage and manipulation • image and data compression • sorting and searching • spelling checking, backtracking • packet routing in a network • geometric problems

6. Goals for today’s lecture • Course outline • Course work • lab assignments • projects • tests, final exam • quiz and class participation (new) • If any time left, start discussing recursion.

7. Data Structures – key to software design • Data structures play a key role in every type of software. • Data structure deals with how to organize the data in the memory while solving a problem in order to reduce • overall running time of a program • response time (for queries) • memory requirements • Cost model for data access - array access, pointers

8. Abstract Data Structure (ADT), supported operations • Dictionary • search • insert primary operations • Delete • deleteMin • Range search • Successor secondary operations • Merge • Priority queue • Insert • deleteMin • Merge, split etc. Secondary operations primary operations

9. Linear data structures • key properties of the (1-d) array: • a sequence of items are stored in consecutive memory locations. • array provides a constant time access to k-th element for any k. • (access the element by: Element[k].)

10. Linear data structures • inserting at the end is easy. • if the current size is s, then we can add x at the end using the single instruction: • Element[s++] = x; • deleting at the end is also easy. • inserting or deleting at any other position is expensive. • searching for a key is expensive (unless sorted). • Expensive means the number of operations ~ size of the array.

11. Images stored in 2-dim arrays • We will work on 2-d arrays by manipulating images: • Each pixel is represented by a blue value, a red value and a green value (any color is a combination of these colors). (255, 255, 255) represents white, (255, 0, 0) represents red etc. • pic(i , j)-> Blue represents the blue component of the i-th row, j-th column pixel of pic and so on. • Some basic operations on images: • open, read, write • rotate, copy a sub-image • filter (remove blemishes) • extract features (identify where buildings are in an aerial photograph)