/*****************************************************************
 * README
 *	-  1. type in "gcc main.c -std=c99 -o main" to generate the main.exe file    
	-  2. type in "./main 10000 topology histogram" to write the topology to the topology.txt file and write histogram to the histogram.txt. These output files will be in the same folder with src code.	

*
 *	-  The graph analysis program reads the file containing the graph topology	*
 *	   produced by the graph generation program in part 1,  and computes the	*
 *	   diameter of the graph.  						*
 *	-  Before excuting the program, make sure to place the output topology file	*
 *	   from program 1 into the same folder as the the source codes.		*
 *	-  Format of the output topo file: 					*
 *	   first line: total number of nodes;					*
 *	   remaining lines: degree of the nodes	        source node node_1 node_2...    *
 *****************************************************************/