func bin2gray(n) {
n ^ (n >> 1);
}
func gray2bin(num) {
var bin = num;
while (num >>= 1) { bin ^= num };
return bin;
0..31 -> each { |i|
var gr = bin2gray(i);
printf("%d\t%b\t%b\t%b\n", i, i, gr, gray2bin(gr));