1. Lecture 20
CSE 331
Oct 15, 2010

2. HW 5 due today I will not take any HW after 1:15pm
Q1 and Q2 in one pile
Q3 in another pile
I will not take any HW after 1:15pm

3. Mid term In class on Monday Will start at 1pm: so come on time
Most of your mid term questions will be answered by the blog post

4. Unclaimed HWs/solutions
Today
hours-a-thon
Unclaimed HWs/solutions
Atri: 2:00-3:30 (Bell 123)
Jeff: 3:30-5:00 (Commons 9)
Alex: 5:00-6:30 (Bell 224)

5. Graded HW 4 and HW 5 solutions
End of the lecture

6. Solutions to Sample Mid-term
Posted on the webpage/blog

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

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

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

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

11. HW 5 due today I will not take any HW after 1:15pm
Q1 and Q2 in one pile
Q3 in another pile
I will not take any HW after 1:15pm

12. Today’s agenda
DAG  topological sorting