Implementation of Fermat's primality test

Question

Who wants to help me with my homework?

I\'m try to implement Fermat\'s primality test in Java using BigIntegers. My implementation is as follows, but unfortunately i

Answer 1

a should be "pick a randomly in the range (1, n − 1]" and I don't really see that happening. You could print a to check that.

As for how to do that:

BigInteger a = BigInteger.valueOf(random.nextInt(n-2)+2);

e.g. You shouldn't use the BigInteger constructor with a Random argument; that's just a source of randomness, but a should be a random value.

The 'random.nextInt(n-1)+1' comes from the definition of nextInt which, given argument k, returns a random value 0 up to and including k-1. And you want a to be larger than 1 and smaller than n.