Using all integers from 1 to 20, assign them into a 5 by 4 grid so that adjacent numbers (horizontally, vertically and diagonally) will differ by at least 4.

(In reply to computer solutions by Charlie)

I didn't try this by hand so I don't know how difficult that would be.

I'm curious if there are solutions with minimum difference 5 (or 6 etc.)

Posted by Jer on 2016-02-14 15:30:09