CountFactors

A positive integer D is a factor of a positive integer N if there exists an integer M such that N = D * M.

For example, 6 is a factor of 24, because M = 4 satisfies the above condition (24 = 6 * 4).

Write a function:

    int solution(int N);

that, given a positive integer N, returns the number of its factors.

For example, given N = 24, the function should return 8, because 24 has 8 factors, namely 1, 2, 3, 4, 6, 8, 12, 24. There are no other factors of 24.

Write an efficient algorithm for the following assumptions:

        N is an integer within the range [1..2,147,483,647].

int solution(int N) {
    // write your code in C++11 (g++ 4.8.2)
    unsigned int i = 1;
    int num = 0;
    while (i * i < (unsigned int)N) {
        if (N % i == 0) {
            num += 2;
        }
        
        i++;
    }
    
    if (i * i == N) {
        num++;    
    }
    
    return int(num);
}