Gray code
Karnaugh maps
Create functions to encode a number to and decode a number from Gray code.

Display the normal binary representations, Gray code representations, and decoded Gray code values for all 5-bit binary numbers (0-31 inclusive, leading 0's not necessary).

There are many possible Gray codes. The following encodes what is called "binary reflected Gray code."

Encoding (MSB is bit 0, b is binary, g is Gray code):

if b[i-1] = 1
   g[i] = not b[i]
else
   g[i] = b[i]
Or:

g = b xor (b logically right shifted 1 time)
Decoding (MSB is bit 0, b is binary, g is Gray code):

b[0] = g[0]

for other bits:
b[i] = g[i] xor b[i-1]
Reference
 Converting Between Gray and Binary Codes. It includes step-by-step animations.
sub bin2gray
{
    return $_[0] ^ ($_[0] >> 1);
}
 
sub gray2bin
{
    my ($num)= @_;
    my $bin= $num;
    while( $num >>= 1 ) {
        # a bit ends up flipped iff an odd number of bits to its left is set.
        $bin ^= $num;   # different from the suggested algorithm;
    }                   # avoids using bit mask and explicit bittery
    return $bin;
}
 
for (0..31) {
    my $gr= bin2gray($_);
    printf "%d\t%b\t%b\t%b\n", $_, $_, $gr, gray2bin($gr);
}