/**

* @function findFactors

* @description Find all the factors of a natural number.

* @param {number} num - A natural number.

* @return {Set<number>} - A set of all the factors of given natural number.

* @see https://en.wikipedia.org/wiki/Divisor

* @example findFactors(1) = [1]

* @example findFactors(4) = [1,2,4]

* @example findFactors(16) = [1,3,5,15]

*/

export const findFactors = (num: number): Set<number> => {

if (num <= 0 || !Number.isInteger(num)) {

throw new Error('Only natural numbers are supported.')

}

const res: Set<number> = new Set()

// Iterates from 1 to square root of num & pushes factors into the res set.

for (let i = 1; i * i <= num; i++) {

if (num % i === 0) {

res.add(i)

const sqrtFactor = Math.floor(num / i)

res.add(sqrtFactor)

}

}

return res

}