1. Definition
In simple terms, an algorithm is a series of instructions to solve a problem (complete a task)
We focus on Deterministic Algorithms
Under the same input it must produce the same output
input
Algorithm
output
Well defined sequence of computer instructions

2. Two Key Properties Correctness Efficiency Time CPU # of instructions
An algorithm is correct if under all valid inputs, it produces the correct output
Efficiency
Same problem can have many ways (algorithms) to solve it
Which one is more efficient?
Efficiency means:
How long will it take?
How much storage will it need?
Time
CPU
# of instructions
Storage
Space
Memory

3. Representative Problems
CS223 Algorithms D-Term 2013
Representative Problems

4. Problem Family I: Sorting
Input
A list of unsorted values
Output
The corresponding sorted list
The algorithm must know how to compare values (<, =, or >)

5. Problem Family II: Searching
Input
A list of values L, and a key (single value) K
Output
The position in L that contain K (if exists)
Search for 33?
Search for C?
Will it make a difference if the list is sorted ???

6. Problem Family III: Trees
Input
A tree of values
Different problems
Traverse the tree and list the values
Search for a value in the tree
Deletion from or insertion into the tree
Can you notice a certain order in this tree?
Binary Search Tree
Left  smaller than
Right  greater than
Binary Tree

7. Problem Family IV: Graphs
Input
A graph of values G
Different problems
Traverse the graph
Searching for a value in the graph
Shortest path from one node to another
What is the shortest path from F to B?
What is the shortest path from F to all other nodes?
Find a minimum spanning tree?

8. Problem Family V: String Processing
Input
One or multiple strings
Different problems
Search for one string in another
Edit distance between strings
String alignment
Search for sentence “algorithms are fun”
Find the smallest difference between this document and another document

9. Too Many Others Protein networks Scheduling problem
Greatest Common Divisor (GCD)
DNA sequence alignment
Nearest neighbor
(closest gas station to me)
Matrix multiplication

10. Course Outline (What You Will Learn)
Algorithmic Strategies and Methodologies
Tree and graph traversal, Greedy Algorithms, Dynamic Programming, Divide and Conquer
Problem Types/Families
Sorting, Searching, Graph and Tree Algorithms, Scheduling and Optimization, String Processing
Algorithms on Different Data Structures
Arrays, Trees, Queues, Graphs, Strings, Hash Tables, Linked Lists
Analysis and Evaluation
Coding and running algorithms,
Analytical analysis using big-O notation

11. CS223 Algorithms D-Term 2015
Course Logistics

12. Textbook Required Introduction to Algorithms
T.H. Cormen, C.E. Leiserson, R.L. Rivest, and C. Stein.
Third Edition, MIT Press, 2009.

13. Course Logistics Website: http://web.cs.wpi.edu/~cs2223/d15
Electronic WPI system: blackboard.wpi.edu
Lectures
MTRF (2:00pm - 2:50pm)
Grading
All assignments are done individually

14. Scheduling Scheduling for assignments, exams, and quizzes
Visit the website:

15. Course Management Course Webpage: Homework/Project submissions
Electronically on blackboard.wpi.edu (Required)
Viewing Grades
On blackboard.wpi.edu

16. Office Hours Posted on the course web page
Covers most days of the week
Make use of them– they are there for YOU !

18. Programming Language In assignments, use Python
In lectures, I will use pseudocode closer to Python