Java | Leetcode Java题解之第507题完美数

题目：

题解：

class Solution {
    public boolean checkPerfectNumber(int num) {
        if (num == 1) {
            return false;
        }

        int sum = 1;
        for (int d = 2; d * d <= num; ++d) {
            if (num % d == 0) {
                sum += d;
                if (d * d < num) {
                    sum += num / d;
                }
            }
        }
        return sum == num;
    }
}