Method 1 - Enter the number of tents horizontally attached to tree. (For the example answer key is 5)

Method 2 - Describe the diagonals using 1 for tents and 0 for no tents (For the example the answer keys are 010000, 000000)

Any other suggestions?

I doubt if diagonals would work in large grids so I go for Method 1.

Another answer key could perhaps be the number of tents in both diagonals.

In this case, it would be (1,0)

Edited by rakesh_rai 2011-07-05 7:39 PM

Rohan mentioned that 'describing diagonals won't work. I'm not sure what he meant, but I think he was trying to say that the diagonals will/may be solved early.
In that case #of tents in both diagonals won't work too.