isPrime
Given a number, return true if the number is prime, otherwise return false.
Examples
isPrime(7) → true
isPrime(10) → false
Starter code
function isPrime(n) {
}
Complexity of the optimal solution
Time O(sqrt(n)), space O(1). The algorithm checks for factors only up to the square root of n. This is a significant optimization over checking up to n. The time complexity is therefore O(sqrt(n)). Space usage is constant.