Better C implementation for Pascals Triangle

pascal2.c

/*
 * Pascal2.c
 *
 * Pascals Triangle in C
 *
 * See notes below.
 * To run: 
		gcc -std=c99 pascal2.c -o  pascal2 && ./pascal2 10
 */

#include <stdio.h>
#include <stdlib.h>

long *pascal( int rows )
{
	long *line = (long*)malloc(sizeof(long)*rows);
	line[0]=1;
	
	int r,c,p1,p2;
	for (r=1,p1=1;r<rows;++r)
	{
		for (c=1; c<r; ++c)
		{
			p2=p1;
			p1=line[c];
			line[c]=p2+p1;
		}
		line[r]=1;
	}
	return line;
}

int main( int argc, char**argv )
{
	if (argc!=2) {
		printf("usage: pascal2 <n>\n");
		exit(1);
	}
	int rows = atoi(argv[1]);
	long *line = pascal(rows);
	int col;
	for (col=0; col<rows; ++col) {
		printf("%ld ",line[col]);
	}
	printf("\n");
	exit(0);
}


/*

Notes for a better implementation:

1
11
121    ... a
1331   ... b
14641

To update in-situ, just need to save overwritten entry or
defer writing until the next column written.

ok, after several minutes, we need to save what we need and
fifo what we are summing for the next line.

p1=before update
p2=previous column before update

b[0]=1
p1=b[0]

i:1->count-2
	p2=p1
	p1=a[i]
	b[i]=p2+p1

b[count-1]=1

*/