Possible Duplicate:Data for testing graph algorithms I recently developed a parallel algorithm to solve the vertex cover problem.now i need some graphs so i can test the speed of my algorithm vs the sequential code.where can i find graphs? i am looking for something similar to this text file:  3 31 01 20 2the first 2 numbers (3 and 3) states that there are 3 vertices and 3 edges in the graph. following this line is 3 edges.
Graphs to download
graph theory;co.combinatorics;graph algorithms;data sets
If you want challenging instances for the vertex cover problem:http://www.nlsde.buaa.edu.cn/~kexu/benchmarks/graph-benchmarks.htm