描述
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.
测试用例
Input: num = 28
Output: true
# Explanation: 28 = 1 + 2 + 4 + 7 + 14
# 1, 2, 4, 7, and 14 are all divisors of 28.题解
完全数刚好等于他所有质子的和。
所以需要求出该数所有的质子。
var checkPerfectNumber = function (num) {
let sum = 0;
// 完全数除以自己一半，求余肯定会大于0，所以用num/2
for (let j = 1; j <= num / 2; j++) {
if (num % j === 0) {
sum += j;
}
}
return sum === num;
};结果
Accepted
98/98 cases passed (1776 ms)
Your runtime beats 57.95 % of javascript submissions
Your memory usage beats 47.02 % of javascript submissions (38.8 MB)
