Reaching Points



Here's a more detailed explanation for
tx != ty
:tx = ty
implies that(txty, ty) = (ty, ty)
or(tx, txty) = (tx, tx)
or that they are the starting points which implies that
tx = 0 or ty = 0
 here the problem states that sx and sy > 0, so it's not possible
 which implies that
Aside from that, nice article !