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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. *

* 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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