feedback-arc-set/generator.c

/**
 * @file generator.c
 * @date 2018-05-21
 *
 * @brief Client program which generates solutions and submits them.
 */

#include "common.h"
#include <limits.h>

static const char *pname;

struct sigaction sa;

struct AdjListNode {
	int dest;
	struct AdjListNode *next;
};

struct AdjList {
	struct AdjListNode *head;
};

struct Graph {
	int V;
	struct AdjList *array;
};

static volatile sig_atomic_t quit = 0;

static void sig_handler(int signum)
{
	quit = 1;
}

void usage(void)
{
	fprintf(stderr, "SYNOPSIS\n"
			"\tgenerator EDGE1...\n"
			"EXAMPLE\n"
			"\tgenerator 0-1 1-2 1-3 1-4 2-4 3-6 4-3 4-5 6-0\n");
	exit(EXIT_FAILURE);
}

struct AdjListNode *newAdjListNode(int dest)
{
	struct AdjListNode *newNode = malloc(sizeof(struct AdjListNode));
	newNode->dest = dest;
	newNode->next = NULL;
	return newNode;
}

struct Graph *createGraph(int V)
{
	struct Graph *graph = malloc(sizeof(struct Graph));
	graph->V = V;

	graph->array = malloc(V * sizeof(struct AdjList));

	for (int i = 0; i < V; i++)
		graph->array[i].head = NULL;
	
	return graph;
}

void addEdge(struct Graph *graph, int src, int dest)
{
	struct AdjListNode *newNode = newAdjListNode(dest);
	newNode->next = graph->array[src].head;
	graph->array[src].head = newNode;
}

int strToInt(char *str)
{
	char *endptr;
	long val;

	val = strtol(str, &endptr, 10);
	if ((errno == ERANGE && (val == LONG_MAX || val == LONG_MIN)) ||
	    (errno != 0)) {
		perror(pname);
		return -2;
	}
	if (val < INT_MIN || val > INT_MAX) {
		fprintf(stderr, "[%s] Please choose a smaller node: ", pname);
		return -1;
	}
	
	return (int) val;
}

struct Graph *parse(int argc, char *argv[])
{
	char *edge;
	char *token;
	char *str;
	int V = 0;
	int src;
	int dest;
	int edges_counter = 0;
	int edges[(argc - 1) * 2];

	for (int i = 1; i < argc; i++) {
		edge = argv[i];
		str = strdup(edge);
		int count = 0;
		while ((token = strsep(&str, "-"))) {
			if (count == 0) {
				src = strToInt(token);
				edges[edges_counter] = src;
				edges_counter++;
				if (src > V)
					V = src;
			}
			if (count == 1) {
				dest = strToInt(token);
				edges[edges_counter] = dest;
				edges_counter++;
				if (dest > V)
					V = dest;
			}
			if (count > 1) {
				fprintf(stderr, "[%s] An edge consists of two "
						"nodes separated by a dash\n", pname);
				free(str);
				exit(EXIT_FAILURE);
			}
			switch (src) {
			case -2:
				free(str);
				exit(EXIT_FAILURE);
				break;
			case -1:
				fprintf(stderr, "%s\n", edge);
				free(str);
				exit(EXIT_FAILURE);
				break;
			default:
				break;
			}

			count++;
		}
	}

	struct Graph *graph = createGraph(V+1);
	for (int i = 0; i < (sizeof(edges) / sizeof(int)); i+=2) {
		addEdge(graph, edges[i], edges[i+1]);
	}

	return graph;
}

void printGraph(struct Graph *graph)
{
	for (int v = 0; v < graph->V; v++) {
		struct AdjListNode* pCrawl = graph->array[v].head;
		printf("\n Adjacency list of vertex %d\n head ", v);
		while (pCrawl) {
			printf("-> %d", pCrawl->dest);
			pCrawl = pCrawl->next;
		}
		printf("\n");
	}
}

int main(int argc, char *argv[])
{
	if (argc == 1)
		usage();
	pname = argv[0];
	
	struct sigaction sa;
	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = &sig_handler;
	sigaction(SIGINT, &sa, NULL);
	sigaction(SIGTERM, &sa, NULL);

	while (quit == 0) {
		struct Graph *graph = parse(argc, argv);
		printGraph(graph);
		break;
	}

	return 0;
}