The gcd(int,int) method of ArithmeticUtils seems 2 times slower than the naive approach using modulo operator. The following test code runs in 11s with current version and in 6s with the patch.
public void testApache()
{
Random rng=new Random(0);
long checksum=0;
long start=System.nanoTime();
checksum+=gcd(0,Integer.MAX_VALUE);
checksum+=gcd(Integer.MAX_VALUE,0);
checksum+=gcd(Integer.MAX_VALUE,rng.nextInt());
for(int i=0;i<10000;i++) checksum+=gcd(rng.nextInt(),Integer.MAX_VALUE);
checksum+=gcd(Integer.MAX_VALUE,Integer.MAX_VALUE);
checksum+=gcd(Integer.MIN_VALUE,1<<30);
checksum+=gcd(1<<30,1<<30);
checksum+=gcd(3 * (1<<20),9 * (1<<15));
for(int i=0;i<30000000;i++) checksum+=gcd(rng.nextInt(),rng.nextInt());
long end=System.nanoTime();
long tns=end-start;
long tms=(tns+500000)/1000000;
long ts=(tms+500)/1000;
System.out.println("exec time="+ts+"s, ("+tms+"ms), checksum="+checksum);
assertEquals(9023314441L,checksum);
}
Improvement
Trivial
