o

To much guessing.

Hint : C1R8.

Hint: C1R9 and the c25r24.

Thanks margpheb.

It's totally logical until the last 48 squares. Then you have only two solution to try. C1R9 is the correct one. It's a lot easier when you start with that hint. So if you want a challenge, wait with hints until you have an open 6x8 rectangle at the top left.