1. Lecture 17
CSE 331
Oct 7, 2011

2. HW 4 due today I will not take any HW after 1:15pm
Q1, Q2 and Q3 in separate piles
I will not take any HW after 1:15pm

3. Mid term Monday in class at 1pm Unfortunately I won’t be there
Jiun-Jie with my PhD students Steve & Swapnoneel will proctor the exam

4. Graded HW 3 & solutions to HW4
Graded HW3 in office-hour-a-thon
Solutions to HW 4 at the end of the lecture

5. On Friday, Oct 7 hours-a-thon Unclaimed HWs and solutions
Atri: 2:00-3:00 (Bell 123)
Jiun-Jie: 4:00-5:00 (Commons 9)
Jesse: 5:00-6:00 (Bell 224)

6. To form a group Can use comment section on the blog
(Do not use the anonymous comment link)

7. If there is interest
Can spend last 10 mins taking questions on the mid-term

8. Directed graphs Model asymmetric relationships
Precedence relationships
u needs to be done before v means (u,v) edge

9. Directed graphs Adjacency matrix is not symmetric
Each vertex has two lists in Adj. list rep.

10. Directed Acyclic Graph (DAG)
No directed cycles
Precedence relationships are consistent

11. Topological Sorting of a DAG
Order the vertices so that all edges go “forward”
Topological sorting  DAG

12. HW 4 due today I will not take any HW after 1:15pm
Q1, Q2 and Q3 in separate piles
I will not take any HW after 1:15pm

13. Today’s agenda
DAG  topological sorting

14. A notation announcement
I will (try to) not use u from now on

15. Run of TopOrd algorithm