[Tex/LaTex] Algorithmic package for loop and comment at the same line

Question

I want to have the following output using algorithmic package:

for i = 1 : z do // number of rows
   x = 1 
end for

I use the following tex code:

\begin{algorithmic}
    \FOR{$p=1:r$} // number of rows
        \STATE $x=1$
    \ENDFOR
\end{algorithmic}

It doesn't work. I couldn't find any way to put the comments to the same line with for. Is there any way to do that with the algorithmic package?

EDIT

1.

Code:

\FOR[// loop over all puppies]{$p=1:r$}
    \STATE $x=1$
\ENDFOR

Result:

for i = 1 : z do {// number of rows}
   x = 1 
end for

2.

Code:

\FOR{$p=1:r$ \COMMENT{// number of rows}}
    \STATE $x=1$
\ENDFOR

Result:

for i = 1 : z {// number of rows} do
   x = 1 
end for

Is there any way to get rid of these curly brackets?