<p>1) There are many different ways to compute the correct row and column numbers needed while filling in the 2D-array. It sounds like the technique you used was appropriate and would be eligible for full points (assuming, of course, you got the details right). I think the modulus arithmetic was more useful for the TokenPass problem — even there, though, there are plenty of ways to solve the problem without modulus.</p>
<p>2) It all depends on which methods you chose to override. The only place you should ever call removeSelfFromGrid() is in makeMove(); doing so in any other method is likely to cause a problem with violating the postconditions. But the “simplest” answer to the problem involves only overriding the getMoveLocations() and selectMoveLocation() methods.</p>