Validate 2sat data

validate.c

/* validate 2sat input data */
#include <stdio.h>
#include <stdlib.h>

#define abs(x) ((x) < 0 ? -(x) : (x))

int main(int argc, char *argv[])
{
	if (argc < 2) {
		printf("usage: %s [file]\n", argv[0]);
		return 1;
	}
	
	FILE *fin = fopen(argv[1], "r");
	int fail = 0;
	int nv = 0, nc = 0;
	int n;
	int i, j, k;
	int *vals;

	fscanf(fin, "%d %d", &nv, &nc);
	vals = calloc((nv > 0 ? nv : 1), sizeof(int));
	if (nc < nv) {
		printf("Number of clauses < number of values\n");
		fail = 1;
		goto end;
	}
	for (i=1; (n = fscanf(fin, "%d %d", &j, &k)) == 2; ++i) {
		if (abs(j) == 0 || abs(k) == 0) {
			printf("Clause contains a zero\n");
			fail = 1;
			goto end;
		} else if (abs(j) > nv || abs(k) > nv) {
			printf("Line %d contains out-of-bounds value(s)\n", 
				i+1);
			fail = 1;
			goto end;
		} else if (i > nc) {
			printf("Number of lines > number of clauses\n");
			fail = 1;
			goto end;
		}
		vals[abs(j)-1] = abs(j);
		vals[abs(k)-1] = abs(k);
	}
	
	if (n != EOF) {
		printf("Line %d contains %d vars\n", i, n);
		fail = 1;
		goto end;
	}
	if (i <= nc) {
		printf("Number of lines < number of clauses\n");
		fail = 1;
		goto end;
	}
	for (i=0; i<nv; ++i)
		if (vals[i] != i+1) {
			printf("var %d not present\n", i+1);
			fail = 1;
		}
end:
	if (fail)
		printf("Invalid data\n");
	else
		printf("Valid data\n");
	free(vals);
	fclose(fin);
	return 0;
}