Question

I have an array a of 10 booleans (or equivalently the binary representation of a number < 1024). I want to compare this array to a large set of arrays b[i] of booleans of the same size in the following way:
The function compare(a,b[i]) should return true if the elements of the array a are never true when the element of at the same position in b[i] is false.

As an exemple in java

boolean compare(boolean a1, boolean a2){
for (int j = 0; j<10; j++) 
   if (a1[j] && !a2[j]) 
      return false;
return true;
}

Is there a better implementation of this function? If one consider the corresponding binary number to be the coefficients of the prime decomposition of a integer A1 (and A2), an equivalent function would be

boolean compare (int A1, int A2){
if (gcd(A1,A2)==A1) 
   return true;
else
   return false;
}

with for example, (http://www.java-tips.org/java-se-tips/java.lang/finding-greatest-common-divisor-recursively.html)

int gcd(int a, int b) {
if (b==0) 
   return a;
else
   return gcd(b, a % b);
}

but I don’t think that this is more efficient (but I may be wrong).

Does anyone has an idea ? All suggestions are welcome!

EDIT: I will go back with some profiling later… Thanks for all your propositions!

Answer 1

If you can use integers instead of arrays, why not just:

return ((a1 & ~a2) == 0)