Just mark `1`

only a position that a bit of x and y are different by using XOR.

After that, just count a number of `1`

of the result of XOR. That's it.

```
func hammingDistance(x int, y int) int {
xor := x ^ y
count := 0
for {
if xor == 0 {
break
}
xor = xor & (xor - 1) // reset the rightmost "1" bit
count++
}
return count
}
```