[math-fun] opposite of Gray code

The "Gray code" is a fast way to produce the integers 0,1,2,..2^p-1 in an order such that each differs from predecessor in exactly 1 bit. Q1 (easy). Find an anti-Gray code where each differs from predecessor in exactly p-1 bits. Q2 (not so easy). Find a "mid-gray" code where each differs from predecessor in exactly p/2 bits (p>1 even). Note this is impossible if p is a multiple of 4. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)