perfect-number

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Algorithms

A <a href="https://en.wikipedia.org/wiki/Perfect_number" target="_blank">perfect number</a> is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. A divisor of an integer <code>x</code> is an integer that can divide <code>x</code> evenly.

Given an integer <code>n</code>, return <code>true</code> if <code>n</code> is a perfect number, otherwise return <code>false</code>.

&nbsp;
Example 1:

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

Example 2:

<pre>
Input: num = 7
Output: false
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= num &lt;= 108</code></li>
</ul>

checkPerfectNumber

Perfect Number

Self Dividing Numbers

self-dividing-numbers

自除数

Math

对于一个&nbsp;正整数，如果它和除了它自身以外的所有 正因子 之和相等，我们称它为 「完美数」。

给定一个&nbsp;整数&nbsp;<code>n</code>，&nbsp;如果是完美数，返回 <code>true</code>；否则返回 <code>false</code>。

&nbsp;

示例 1：

<pre>
输入：num = 28
输出：true
解释：28 = 1 + 2 + 4 + 7 + 14
1, 2, 4, 7, 和 14 是 28 的所有正因子。</pre>

示例 2：

<pre>
输入：num = 7
输出：false
</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= num &lt;= 108</code></li>
</ul>