# LeetCode - 0507. Perfect Number
### 題目網址：https://leetcode.com/problems/perfect-number/
###### tags: `LeetCode` `Easy` `數學` `質數`

/*
    -LeetCode format-
    Problem: 507. Perfect Number
    Difficulty: Easy
    
    by Inversionpeter
*/



class Solution {
    
    int FactorsSum(int number) {
        int buffer = sqrt(number), base, temporary, sums = 1;
        for (int i = 2; i <= buffer; ++i)
            if (!(number % i)) {
                temporary = 1, base = 1;
                do {
                    base *= i, temporary += base, number /= i;
                } while (!(number % i));
                sums *= temporary, buffer = sqrt(number);
            }
        if (number != 1) 
            sums *= (number + 1);
        return sums;
    }
    
public:
    bool checkPerfectNumber(int num) {
        return num > 0 && (FactorsSum(num) == (num << 1));
    }
};