Complex code/algorithm optimization (e.g. simplification) quandary

Question

How can this code be simplified?

  if      (x == 0) x = 1;
  else if (x == 1) x = 0;
  else if (x == 2) x = 3;
  else if (x == 3) x = 2;

Answer 1

If x is always between 0 and 3 then try this:

x ^= 1;

It toggles the least significant bit.

If x can be a value other than between 0 to 3 then you can first test for that:

if (x >= 0 && x <= 3) {
    x ^= 1;
}