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Three-divisors

Problem Description​

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​

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 Approach​

Intuition:​

To efficiently determine the number that is divisible by 3 integers.

Solution Implementation​

Code (C++):​

class Solution {
public:
    bool isThree(int n) {
        int cnt = 0;
        for(int i=1; i<=n; i++){
            if(n%i==0) cnt++;
        }
        if(cnt==3) return true;
        return false;
    }
};