algorithms/prime

Define a function that takes an integer argument and returns logical value true or false depending on if the integer is a prime.

Per Wikipedia, a prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself. Example

is_prime(1)  /* false */
is_prime(2)  /* true  */
is_prime(-1) /* false */

Assumptions

• You can assume you will be given an integer input.
• You can not assume that the integer will be only positive. You may be given negative numbers as well (or 0).
• There are no fancy optimizations required, but still the most trivial solutions might time out. Try to find a solution which does not loop all the way up to n.