hi harrym.
I'll show you which tree can be visible in sample input case. I hope this helps you. Points have beeen sorted by distance between tree and observer.
Code: Select all
visible: (0,0)
visible: (1,0)
visible: (0,1)
visible: (1,1)
visible: (0,-1)
visible: (1,-1)
visible: (-1,0)
visible: (2,0)
visible: (-1,1)
visible: (2,1)
visible: (0,2)
visible: (1,2)
visible: (2,-1)
visible: (-1,2)
visible: (0,-2)
visible: (1,-2)
visible: (-2,0)
visible: (-2,1)
visible: (3,0)
visible: (3,1)
visible: (0,3)
visible: (1,3)
visible: (-1,-2)
visible: (-2,-1)
visible: (2,-2)
visible: (3,-1)
visible: (-2,2)
visible: (-1,3)
visible: (3,2)
visible: (2,3)
visible: (0,-3)
visible: (1,-3)
visible: (-3,0)
visible: (-3,1)
visible: (4,0)
visible: (4,1)
visible: (0,4)
visible: (1,4)
visible: (-1,-3)
visible: (2,-3)
visible: (-3,-1)
visible: (4,-1)
visible: (4,2)
visible: (-1,4)
visible: (2,4)
visible: (-2,-3)
visible: (3,-3)
visible: (-3,3)
visible: (0,-4)
visible: (4,3)
visible: (1,-4)
visible: (3,4)
visible: (-4,1)
visible: (5,1)
visible: (0,5)
visible: (1,5)
visible: (-4,-1)
visible: (-4,2)
visible: (5,-1)
visible: (-2,-4)
visible: (3,-4)
visible: (-4,3)
visible: (5,3)
visible: (3,5)
visible: (1,-5)
visible: (-5,1)
visible: (-1,-5)
visible: (6,1)
visible: (-3,-4)
visible: (2,-5)
visible: (4,-4)
visible: (1,6)
visible: (-5,2)
visible: (-4,4)
visible: (6,2)
visible: (5,4)
visible: (2,6)
visible: (-5,-2)
visible: (6,-2)
visible: (-2,6)
visible: (3,6)
visible: (-5,-3)
visible: (-6,1)
visible: (-1,-6)
visible: (7,1)
visible: (-3,6)
visible: (-6,-1)
visible: (4,6)
visible: (-1,7)
visible: (-2,-6)
visible: (-6,-2)
visible: (7,-2)
visible: (-4,-5)
visible: (5,-5)
visible: (-2,7)
visible: (3,7)
visible: (-5,5)
visible: (6,5)
visible: (4,-6)
visible: (-6,4)
visible: (7,4)
visible: (-7,-1)
visible: (-7,2)
visible: (8,-1)
visible: (8,2)
visible: (-4,-6)
visible: (5,-6)
visible: (-6,5)
visible: (7,5)
visible: (8,-3)
visible: (-5,-6)
visible: (6,-6)
visible: (2,-8)
visible: (-6,6)
visible: (7,6)
visible: (8,-4)
visible: (2,9)
visible: (3,-8)
visible: (-7,5)
visible: (3,9)
visible: (6,8)
visible: (3,-9)
visible: (10,3)
visible: (-5,9)
visible: (7,-8)
visible: (11,2)
visible: (9,7)
visible: (-5,-9)