In my viewpoint
________
| ##### |
@#####@
#######
#######
#######
####### in this situation the mark "@" can be removed
because it is connected by two v-lines and one h-line
@__###&
&&| &&&&
&&| &&&&
&&|____@ in this situation the mark "@" can also be removed
because it is connected by two h-lines and one v-line
the difference between the two cases is that
I draw the lines in the outer section of the grid in the first
and in the inner section of the grid in the second
the line can be draw in the spaces left by previous removed
tiles or the bound of the grid
if the tiles are adjoined you also can remove them
the problem says that ->
"(As a side effect, this also means that you can remove two tiles of the same picture that are next to each other in horizontal or diagonal."
I think the problemsetter want to express that in horizontal or vertical,
not diagnal.
Sorry, I am poor in English.
![:D](./images/smilies/icon_biggrin.gif)