Codility: CountFactors Solution

Approach

If number a is a divisor of n, then n/a is also a divisor.

One of these two divisors is less than or equal to sqrt(n).

This could be proven by contradictory. Assume if that were not the case, n would be a product of two numbers greater than sqrt(n), which is impossible.

Implementation

1function solution(N) {
2  let result = 0
3  let i = 1
4  while (i * i < N) {
5    if (N % i === 0) {
6      result += 2
7    }
8    i++
9  }
10  if (i * i === N) {
11    result++
12  }
13
14  return result
15}