Lecture 14
CSE 331
Oct 5, 2009
Extra lectures on proofs
Tuesday 5-6pm (Jeff)
Wednesday 4:30-6pm (Atri)
Commons 9
Prefer my name to
Professor/Dr. Rudra
Next Week
I will be out of town
Mon+Wed lecture by Hung Ngo
Mid-term
Scribe
needed for
Wed
Proctored by Hung and couple of Ph.D. students
Sample mid-term will be handed out on Friday
Jeff’s recitations
Flat tire today
A BFS run
L0 = {s}
Assume L0,..,Lj have been constructed
Lj+1 set of vertices not chosen yet but are connected to Lj
Stop when new layer is empty
1
2
7
L0
1
2
3
L1
3
8
4
5
6
4
5
6
7
8
L2
L3
A DFS run
DFS(u)
u is explored
1
1
7
For every unexplored
neighbor v of u
2
2
3
DFS(v)
8
4
4
5
5
6
6
3
8
7
Today’s agenda
Run-time analysis of BFS (DFS)
Stacks and Queues
Last in First out
First in First out
Graph representations
0
1
1
1
0
0
1
0
0
Better for
sparse graphs
and traversals
Adjacency matrix
O(1)
Adjacency List
(u,v) in E?
O(n) [ O(nv) ]
O(n)
All neighbors of u?
O(nu)
O(n2)
Space?
O(m+n)