[leetcode] problem 507 – perfect number

We define the Perfect Number is a positive integer that is equal to the sum of all its positive divisors except itself.

Now, given an integer n, write a function that returns true when it is a perfect number and false when it is not.

Example

Note

Code

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public boolean (int num) {
    if (num == 1)
        return false;

    int sum = 1;

    for (int i = 2; i <= num / i; i++) {
        if (num % i == 0)
            sum += (i == num / i) ? i : i + num / i;
    }

    return sum == num;
}