leetcode-solution-javascript/checkperfectnumber.js at main · iamsajithsasi/leetcode-solution-javascript · GitHub

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/*
Perfect Number

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:
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:
Input: num = 6
Output: true

Example 3:
Input: num = 496
Output: true

Example 4:
Input: num = 8128
Output: true

Example 5:
Input: num = 2
Output: false
*/

/**
 * @param {number} num
 * @return {boolean}
 */
var checkPerfectNumber = function (num) {
    if (num == 1) return false;

    let divisors = 0;

    for (let i = 1; i < num / 2 + 1; i++) { // num / 2 + 1 => to reduce loops
        if (num % i == 0) { divisors += i }
    };

    return divisors === num
};