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.
fn gray_encode(integer: u64) -> u64 {
    (integer >> 1) ^ integer
}
 
fn gray_decode(integer: u64) -> u64 {
    match integer {
        0 => 0,
        _ => integer ^ gray_decode(integer >> 1)
    }
}
 
fn main() {
    for i in 0..32 {
        println!("{:2} {:0>5b} {:0>5b} {:2}", i, i, gray_encode(i),
            gray_decode(i));
    }
 
}