34 lines
1.0 KiB
Java
34 lines
1.0 KiB
Java
|
package Maths;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* In number theory, a perfect number is a positive integer that is equal to the sum of
|
||
|
|
* its positive divisors, excluding the number itself. For instance, 6 has divisors 1, 2 and 3
|
||
|
|
* (excluding itself), and 1 + 2 + 3 = 6, so 6 is a perfect number.
|
||
|
|
* <p>
|
||
|
|
* link:https://en.wikipedia.org/wiki/Perfect_number
|
||
|
|
* </p>
|
||
|
|
*/
|
||
|
|
public class PerfectNumber {
|
||
|
|
public static void main(String[] args) {
|
||
|
|
assert isPerfectNumber(6); /* 1 + 2 + 3 == 6 */
|
||
|
|
assert !isPerfectNumber(8); /* 1 + 2 + 4 != 8 */
|
||
|
|
assert isPerfectNumber(28); /* 1 + 2 + 4 + 7 + 14 == 28 */
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Check if {@code number} is perfect number or not
|
||
|
|
*
|
||
|
|
* @param number the number
|
||
|
|
* @return {@code true} if {@code number} is perfect number, otherwise false
|
||
|
|
*/
|
||
|
|
public static boolean isPerfectNumber(int number) {
|
||
|
|
int sum = 0; /* sum of its positive divisors */
|
||
|
|
for (int i = 1; i < number; ++i) {
|
||
|
|
if (number % i == 0) {
|
||
|
|
sum += i;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return sum == number;
|
||
|
|
}
|
||
|
|
}
|