Three Divisors

Given an integer n, return true if n has exactly three positive divisors. Otherwise, return false.

An integer m is a divisor of n if there exists an integer k such that n = k * m.

Example 1:

Input: n = 2
Output: false
Explantion: 2 has only two divisors: 1 and 2.

Example 2:

Input: n = 4
Output: true
Explantion: 4 has three divisors: 1, 2, and 4.

Constraints:

• 1 <= n <= 104

SOLUTION:

class Solution:
    def isThree(self, n: int) -> bool:
        ctr = 0
        for i in range(1, n + 1):
            if n % i == 0:
                ctr += 1
        return ctr == 3