1. Unweighted Shortest Path Neil Tang 3/11/2010
CS223 Advanced Data Structures and Algorithms

2. CS223 Advanced Data Structures and Algorithms
Class Overview
The unweighted shortest path problem
Breadth First Search (BFS)
The algorithms
Time complexity
CS223 Advanced Data Structures and Algorithms

3. Unweighted Shortest Path Problem
The unweighted shortest path problem: Given an unweighted graph G and a source vertex s, find a path from s to every other vertex in G with a minimum number of edges.
CS223 Advanced Data Structures and Algorithms

4. CS223 Advanced Data Structures and Algorithms
BFS
CS223 Advanced Data Structures and Algorithms

5. CS223 Advanced Data Structures and Algorithms
An Algorithm
Time complexity: O(|V|2)
CS223 Advanced Data Structures and Algorithms

6. CS223 Advanced Data Structures and Algorithms
Time Complexity
A bad case
More efficient implementation: Use a queue
Time complexity of a queue-based implementation: O(|V|+|E|)
CS223 Advanced Data Structures and Algorithms