#+title: Notes
* i want help from math
https://math.stackexchange.com/questions/28503/how-to-find-intersection-of-two-lines-in-3d

'vector parametric form' is exactly what we're getting in the input?
* huh and only 'looking forward in time' so solutions with negative t are not important.
cooool
** i see that speeds are integers, so updated points are integers.
maybe i do calculation of every line on every time point?

and if i do that is there a way to get intersections efficietly?
** i'll also need the ends for lines? ends to the line segments.
with limits on the x & y by the task

for example both 7 <= <= 27
for input 200000000000000 <= <= 400000000000000

also. can't we move the coords? maybe not? maybe only for one
so, what do i do? to get the ends of the lines?
i try to calcluate with both x & y in 2 min\max. then if the other is ok, than that's the ends?
wait, what happens when i do x = 7, and x = 27 and y is outside? it means no intesections, i guess
or it could be outside from different sides, so not all x are ok, but there's still line there
* Using homogeneous coordinates
https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection
no, i don't understant that
* https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection#Given_two_points_on_each_line
with 2 points. i guess
but also - check if the point in future of the hail, by comparing with speeds?
should be easy