Hiroimono (1008)

Find a path which starts at one of the stones(circles) and encounters all other stones in the grid. The path may only travel in orthogonal directions, and may only turn at a right angle when it encounters a stone for the first time. (If the path encounters the same stone later, it may not turn then.) The path may not turn at any other angles, including going backwards. (The path may not go through a stone without encountering it. The path may intersect and overlap with itself.)

Reference: WPF (1)