【leetcode刷题】T203-完美数

示例：

输入: 28
输出: True
解释: 28 = 1 + 2 + 4 + 7 + 14

class Solution(object):
    def checkPerfectNumber(self, num):
        """
        :type num: int
        :rtype: bool
        """
        # 特殊情况
        if num <= 1:
            return False

        res = -num
        for i in range(1, int(math.sqrt(num)) + 1):
            if num % i == 0:
                res += i + num / i
        return res == num

class Solution {
public:
    bool checkPerfectNumber(int num) {
        if(num < 2)
            return false;
        int res = -num;
        for(int i=1; i<(int)sqrt(num)+1; i++){
            if(num % i == 0)
                res += i + num / i;
        }
        cout << res << endl;
        return res == num;
    }
};