Count the Primes in Rust

Given an array of integers nums, return how many of them are prime numbers.

A prime number is greater than 1 and can be divided evenly only by 1 and by itself: 2, 3, 5, 7, 11, 13 and so on. 0 and 1 are not prime. If a number appears more than once, each appearance counts.

The work is split between two functions. The first one is a helper: it gets one number and returns true if it is prime, false if it is not. The second one, the function that is graded, goes over the numbers and counts the ones the helper says are prime.

Example 1:

Input: nums = [2, 3, 4, 5, 6]
Output: 3
Explanation: 2, 3 and 5 are prime. 4 = 2 × 2 and 6 = 2 × 3 are not.

Example 2:

Input: nums = [0, 1, 9]
Output: 0
Explanation: 0 and 1 are never prime, and 9 = 3 × 3.

Example 3:

Input: nums = [7, 10, 7]
Output: 2
Explanation: 7 is prime and appears twice, so it counts twice. 10 = 2 × 5 is not prime.

Constraints:

• nums has at least one number.
• Every number is an integer from 0 to 100000.