DSA1 | Week 5
DeBruijn Sequences, BFS & DFS
Summary from last week
The Cardstack data structure
Deques | Stacks | Queues
De-Bruijn Sequences
| Adj. Matrix | Adj. List | Edge List | |
|---|---|---|---|
| Adding a vertex | Painful | Tolerable | Decent |
| Deleting a vertex | Painful | Tolerable | Tolerable |
| Adding an edge | Brilliant | Brilliant | Brilliant |
| Deleting an edge | Brilliant | Decent | Tolerable |
| Finding degree(v) | Tolerable | Decent | Tolerable |
| Check if (u,v) is an edge | Brilliant | Decent | Tolerable |
Recap: what we have seen so far
Graph Representations
1
2
3
4
5
6
7
8
9
Try them all
Explore one thoroughly
What do you do when you have many different options?
Navigating Graphs
Navigating Graphs
Try them all
Explore one thoroughly
What do you do when you have many different options?
Phase 0.
Identify a
starting point \(s\).
Phase 1.
Collect
all friends of \(s\).
Phase 0.
Identify a
starting point \(s\).
Phase 1.
Collect
all friends of \(s\).
Phase 0.
Identify a
starting point \(s\).
Phase k.
Collect
anyone who is a
friend of
anyone seen before.
\(\cdots\)
\(s\)
\(x\)
\(y\)
\(w\)
\(z\)
\(s\)
\(x\)
\(y\)
\(w\)
\(z\)
\(s\)
\(x\)
\(y\)
\(w\)
\(z\)
\(s\)
\(x\)
\(y\)
\(w\)
\(z\)
Phase 1.
Collect
all friends of \(s\).
Phase 0.
Identify a
starting point \(s\).
Phase k.
Collect
anyone NEW
who is a
friend of
anyone seen before.
\(\cdots\)
Phase 1.
Collect
all friends of \(s\).
Phase 0.
Identify a
starting point \(s\).
Phase k.
Collect
anyone NEW
who is a
friend of
anyone seen before.
\(\cdots\)
Implementation?
ask every unvisited node if
they are adjacent to
any visited node.
Phase #\(k\).
Try them all
Explore one thoroughly
What do you do when you have many different options?
Navigating Graphs
Thanks, XKCD.
Thanks, Wikipedia.
DSA1 | Week 5
By Neeldhara Misra
