Java/Maths/PerfectNumber.java at master · ppdouble/Java · GitHub

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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

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;

}

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