Euclidean Algorithm

EuclideanAlgorithm.java

public class EuclideanAlgorithm {
    
    private final List<Long> numbers;
    
    public EuclideanAlgorithm(final List<Long> numbers) {
        this.numbers = Collections.unmodifiableList(numbers);
    }
    
    public long calculateGCD() {        
        Iterator<Long> it = numbers.iterator();
        long result = it.next().longValue();
        while(it.hasNext()) {
            result = gcd(result, it.next().longValue());
        }
        return result;
    }
    
    public long calculateLCM() {        
        Iterator<Long> it = numbers.iterator();
        long result = it.next().longValue();
        while(it.hasNext()) {
            result = lcm(result, it.next().longValue());
        }
        return result;
    }
    
    private long gcd(long n1, long n2) {
        return (n2 == 0) ? n1 : gcd(n2, n1 % n2);
    }
    
    /**
     * https://en.wikipedia.org/wiki/Least_common_multiple#Reduction_by_the_greatest_common_divisor
     */
    private long lcm(long a, long b) {
        return a * (b / gcd(a, b));
    }      
}