Created
June 29, 2018 12:25
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Perfect number checker
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| /** | |
| * Indicates whether the sum of the factors of a number | |
| * are equal to the number | |
| * https://en.wikipedia.org/wiki/Perfect_number | |
| * | |
| * @param {Number} num | |
| * @returns {Boolean} | |
| */ | |
| function isPerfectNumber (num) { | |
| const numRoot = Math.sqrt(num) | |
| const isEven = num % 2 === 0 | |
| const incr = isEven ? 1 : 2 | |
| let factorsSum = 1 | |
| for (let factor = isEven ? 2 : 3; factor <= numRoot; factor += incr) { | |
| if (num % factor === 0) { | |
| const compliment = num / factor | |
| factorsSum += factor | |
| if (compliment !== factor) { | |
| factorsSum += compliment | |
| } | |
| } | |
| } | |
| return factorsSum === num | |
| } |
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