Question

My problem is very similar to eight queens puzzle.

I’ve got 2-dimensional array (N x N) that for example, looks like this:

0,0,0,0,1 y 0,0,0,0,0 | 0,0,0,0,0 V 0,0,0,1,0 0,0,0,0,0 x-> 

I’m checking horizontally, vertically and diagonally for occurrences of 1

\,0,|,0,/ 0,\,|,/,0 -,-,1,-,- 0,/,|,\,0 /,0,|,0,\ 

I’m thinking about storing only the (x,y) postions of ‘1”s in a list

[[4,0],[3,3]] 

and solving it mathematically, check every position of ‘1’ with another (x1,y1)<->(x2,y2),

if x1 == x2 or y1 == y2 we have a collision! if not check:

x2 == x1 + z; y2 == y1 + z; x2 == x1 - z; y2 == y1 - z; 

(???)

where z is +/- that ( x1+z in 0..N ) and ( y1+z in 0..N ) .......

My problem is checking for diagonal collision, is there a better way to do it???

Answer 1

One possible solution:

def collision(x1, y1, x2, y2):     return x1 == x2 or y1 == y2 or abs(x1-x2) == abs(y1-y2) 

i.e. there is a collision if the two points are on the same horizontal row, same vertical row or same diagonal (vertical distance == horizontal distance).