Getting Factors of a Number

Question

I\'m trying to refactor this algorithm to make it faster. What would be the first refactoring here for speed?

public int GetHowManyFactors(int numberToCheck         


        

Answer 1

I got pretty good results with complexity of O(sqrt(N)).

if (N == 1) return 1;
    int divisors = 0;
    int max = N;
    for (int div = 1; div < max; div++) {
        if (N % div == 0) {
            divisors++;
            if (div != N/div) {
                divisors++;
            }
        }
        if (N/div < max) {
            max = N/div;
        }
    }
    return divisors;