Jagged Array?

I suppose you could do to the extent that the remaining elements in a given row are all zero.

For example:

0 0 1 0 0
0 0 0 1 0
1 0 0 0 0
1 0 1 0 1
0 1 0 0 0

could be stored in jagged form as:

0 0 1
0 0 0 1
1
1 0 1 0 1
0 1

However, a better idea might be to store the non-zero elements in a Dictionary which maps a (row, column) pair to a value. That way no zero elements would be stored at all.

In the above example (.NET 4.0 or later), we would have:

var sparse  = new Dictionary, int>();
dict.Add(Tuple.Create(0,2), 1);
dictAdd(Tuple.Create(1,3), 1);
// and so on