Summing Cells Right-to-Left until a Cell with Value "0" is detected

Hi,

I have a single row of numbers using columns A1:U1 (row1).
The goal is to sum the cells from Right-to-Left "U1:A1" until a value "0" is detected; the sums totalled at that point are the result.

This formula provided to me works Left-to-Right "A1:U1".
=SUM(OFFSET(A1,,,,MATCH(0,A1:U1,0)))
But not in the direction Right-to-Left "U1:A1:" that's needed.

Here's a sample row:

11, 12, 3, 0, 8, 7, 8, 6, 15, 15, 20, 0, 10, 15, 20, 20, 10, 15, 0, 10, 19

In the above A1=11 and U1=19
The correct result would be "29" going Right-to-Left.
There can be multiple "0"s in the series but only the first one found matters.
It's possible there may be no "0"'s.

I plan on copying the formula for use on multiple rows.

Any help would be fabulous and appreciated.

Chubs