CSCI 62Data Structures

Dr. Joshua StoughNovember 20, 2008

Today

• Program 7• Finish hashtables• What are Graphs, what to do with

them (more on Tuesday)• Intro C++

Evaluation Notes

• Assignments – Too hard: 3 (esp. HuffmanTree)– Right: 1– Easy: 2– Not related enough to class: 1– Vague: 2– Is the grading harsh?

• More modular: why, what, show: 1• More lab: 7

Evaluation Notes

• It’s expected that you don’t know C++.– We will be implementing some of the

data structures we’ve covered.• Uneven difficulty in assignments.

– Start early to know how to schedule.– We’ll do smaller assignments.

• Greatest band: Led Zeppelin or The Beatles

More on Maps

• MapVector

• ChainedHashTable – – Replace an association at a bin with a

list of associations at a bin.– collisions result in appending to the

list of associations at that bin.– Complexity as related to loadFactor?

Hashing issues

Hashing issues

Some Map review

Graphs

• Vertex, edge, label, • Edge is incident to two vertices

– Undirected if vertex order irrelevant– Directed otherwise.

• Path-sequence of distinct edges– Simple- vertices are distinct

• Vertices are connected if there’s a simple path between them.– Strongly connected if bi-directional

GraphMatrix

Algorithms

• Reachability• Topological Sort –vertices ordered• Transitive Closure- reachability for

all pairs– Warshall’s

• All pairs minimum distance– Floyd

• Single-source, shortest path– Dijkstra