# Perfect Number Problem

## Description

LeetCode Problem 507.

A perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. A divisor of an integer x is an integer that can divide x evenly.

Given an integer n, return true if n is a perfect number, otherwise return false.

Example 1:

``````1
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Input: num = 28
Output: true
Explanation: 28 = 1 + 2 + 4 + 7 + 14
1, 2, 4, 7, and 14 are all divisors of 28.
``````

Example 2:

``````1
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Input: num = 6
Output: true
``````

Example 3:

``````1
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Input: num = 496
Output: true
``````

Example 4:

``````1
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Input: num = 8128
Output: true
``````

Example 5:

``````1
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Input: num = 2
Output: false
``````

Constraints:

• 1 <= num <= 10^8

## Sample C++ Code

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class Solution {
public:
bool checkPerfectNumber(int num) {
int sum = 1;
if (num == 1)
return false;
for (int i = 2; i < sqrt(num); i ++) {
if (num % i == 0) {
sum += i;
if (num / i != i)
sum += num / i;
}
}
return (sum == num);
}
};
``````