1. Lecture 17
CSE 331
Oct 7, 2016

2. Homework 5

3. Solutions to HW 4
End of the lecture

4. Quiz 1 on Monday

5. Main Steps in Algorithm Design
Problem Statement
Problem Definition n!
Algorithm
“Implementation”
Data Structures
Analysis
Correctness+Runtime Analysis

6. A tool to define problems
Where do graphs fit in?
Problem Statement
A tool to define problems
Problem Definition
Algorithm
“Implementation”
Data Structures
Analysis
Correctness+Runtime Analysis

7. Three general techniques
Rest of the course
Problem Statement
Problem Definition
Three general techniques
Algorithm
“Implementation”
Data Structures
Analysis
Correctness+Runtime Analysis

8. Greedy algorithms Build the final solution piece by piece
Being short sighted on each piece
Never undo a decision
Know when you see it

9. End of Semester blues
Can only do one thing at any day: what is the maximum number of tasks that you can do?
Write up a term paper
Party!
331 homework
Exam study
331 HW
Project
Monday
Tuesday
Wednesday
Thursday
Friday

10. Greedily solve your blues!
Arrange tasks in some order and iteratively pick non-overlapping tasks
Write up a term paper
Party!
Exam study
331 HW
Project
Monday
Tuesday
Wednesday
Thursday
Friday

11. Ordering is crucial Order by starting time Write up a term paper
Algo =1
Party!
Exam study
331 HW
Project
Monday
Tuesday
Wednesday
Thursday
Friday

12. Ordering by least conflicts doesn’t work
Another attempt
Order by duration
Ordering by least conflicts doesn’t work
Algo =1
Monday
Tuesday
Wednesday
Thursday
Friday

13. Order tasks by their END time
The final algorithm
Order tasks by their END time
Write up a term paper
Party!
Exam study
331 HW
Project
Monday
Tuesday
Wednesday
Thursday
Friday

14. Questions?

15. Today’s agenda
Prove the correctness of the algorithm

16. Formal Algorithm R: set of requests Set S to be the empty set
While R is not empty
Choose i in R with the earliest finish time
Add i to S
Remove all requests that conflict with i from R
Return S*= S