Question

I am manipulating many instances of the same data structure which can have one of four states. Currently I implement the states using True/False pairs:

(True, True)
(True, False)
(False, True)
(False, False)

With those data-structures I repeatedly apply two functions f, g where

g((True, True)) = (True, False)
g((True, False)) = (True, True)
g((False, True)) = (False, False)
g((False, False)) = (False, True)

and

f((True, True)) = (False, False)
f((True, False)) = (False, True)
f((False, True)) = (True, False)
f((False, False)) = (True, True)

Can I improve upon this data structure for those two functions? (I want to optimise for speed.)

Answer 1

Use an integer in the range of 0..3 and implement the state transitions with bit arithmetic (g xors with 1; f xors with 3).