Problem
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 <= 10^4
Solution (Java)
class Solution {
public boolean isThree(int n) {
int divisors = 0;
for (int i = 1; i <= n; i++) {
if (n % i == 0) {
divisors++;
}
}
return divisors == 3;
}
}
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).