what is the fastest algorithm for permutations of three condition?

Question

Can anybody help me regarding quickest method for evaluating three conditions in minimum steps? I have three conditions and if any of the two comes out to be true,then whole expression becomes true else false.

I have tried two methods:

if ((condition1 && condition2) || 
    (condition1 && condition3) || 
    (condition2 && condition3))

Another way is to by introducing variable i and

i = 0;
if (condition1) i++;
if (condition2) i++;
if (condition3) i++;
if (i >= 2)
    //do something

I want any other effective method better than the above two.

I am working in a memory constrained environment (Atmeta8 with 8 KB of flash memory) and need a solution that works in C.

Answer 1

This can be reduced to:

if((condition1 && (condition2 || condition3)) || (condition2 && condition3))
    //do something

Depending on the likelihood of each condition, you may be able to optimize the ordering to get faster short-circuits (although this would probably be premature optimization...)