Quoting the problem statement:
Lines passing through white circles must pass straight through the cell, and make a right-angled turn in a cell next to the white circle (left or right)
However, in the given example, if I've read it right, the path passes through the cells (7, 5) and (7, 4), both containing white circles. Going by the rule, there would have to be a right-angled turn in cell (7, 4). Is there an exception in case of adjacent white cells?
In this case, would a path passing straight through (4, 2), (4, 3), (4, 4) be valid?