ansaurus

Question

Answer 1

+11 A:

abs(a.x - b.x) + abs(a.y - b.y) == 1

John Kugelman 2009-07-03 02:53:12

Answer 2

+3 A:

(a.x - b.x) ^ 2 + (a.y - b.y) ^ 2 = 1

Michael Bray 2009-07-03 02:54:02

Squaring the values is completely redundant (1 ^ 2 = 1)

Alex Barrett 2009-07-03 03:05:17

not true... it's purposed is to correct the sign when a.x - b.x = -1 or a.y - b.y = -1 (just as 'abs' does in the accepted answer)

Michael Bray 2009-07-03 03:06:58

Squaring is more expensive though I'd think.

Matthew Scharley 2009-07-03 03:20:26

I agree... which is why I voted up the other answer. :)

Michael Bray 2009-07-03 03:32:56

The most elegant method for determing if two positions in a grid are adjacent.