count-the-divisors-of-a-number.md

Count the divisors of a number ^{7 Kyu}

^{LINK TO THE KATA - NUMBER THEORY MATHEMATICS FUNDAMENTALS}

Description

Count the number of divisors of a positive integer n.

Random tests go up to n = 500000.

Examples (input --> output)

4 --> 3 // we have 3 divisors - 1, 2 and 4
5 --> 2 // we have 2 divisors - 1 and 5
12 --> 6 // we have 6 divisors - 1, 2, 3, 4, 6 and 12
30 --> 8 // we have 8 divisors - 1, 2, 3, 5, 6, 10, 15 and 30

Note you should only return a number, the count of divisors. The numbers between parentheses are shown only for you to see which numbers are counted in each case.

Solution

const getDivisorsCnt = n => {
  let count = 0

  for (let i = 1; i <= Math.sqrt(n); i++) {
    if (n % i === 0) {
      if (i === Math.sqrt(n)) {
        count++
      } else {
        count += 2
      }
    }
  }

  return count
}