// To read a graph (in argv[1], say) from a file, do the following
//
// 	GraphInfo g;
// 	readGraph(argv[1], g);
//
// somewhere in your code.  This method reads the graph into a GraphInfo
// object which has four members:
//
// 	name - the name of the graph (a character array of size 80)
// 	nNodes - the number of nodes (an integer)
// 	nEdges - the number of edges (an integer)
// 	edges - an array of EdgeInfo objects
//
// Each EdgeInfo object has two members, integers u and v, which are the
// labels for the nodes on that edge.
//
// Note that this method doesn't actually construct the graph data
// structure.  You will need to do this yourself.  This method simply
// extracts all of the necessary data from the file, so you don't have to
// deal with I/O.
//
// Also note that the readGraph function returns false when either the
// file is not found, or it is improperly formatted.

#include <fstream.h>
#include <stdio.h>

class EdgeInfo {
public:
	int u;
	int v;

	~EdgeInfo() {
	}

	void print() {
		printf("(%d,%d)", u, v);
	}
};

class GraphInfo {
public:
	char name[80];
	int nNodes;
	int nEdges;
	EdgeInfo *edges;

	GraphInfo() {
		edges = 0;
	}

	~GraphInfo() {
		if (edges != 0) {
			delete[] edges;
		}
	}

	void print() {
		printf("name: %s\n", name);
		printf("nNodes: %d\n", nNodes);
		printf("nEdges: %d\n", nEdges);

		printf("edges: {");

		for (int i=0; i<nEdges-1; i++) {
			edges[i].print();
			printf(",");
		}

		edges[nEdges-1].print();
		printf("}\n");
	}
};

bool readGraph(char *filename, GraphInfo &g) {
	ifstream ifs(filename);

	if (!ifs) {
		return false;
	}

	ifs.getline(g.name, 80);

	if (!(ifs >> g.nNodes)) return false;
	if (!(ifs >> g.nEdges)) return false;

	g.edges = new EdgeInfo[g.nEdges];

	for (int i=0; i<g.nEdges; i++) {
		if (!(ifs >> g.edges[i].u)) return false;
		if (!(ifs >> g.edges[i].v)) return false;
	}

	return true;
}