Print all unique combination of factors of a given number

Question

What is the most efficient algorithm to print all unique combinations of factors of a positive integer. For example if the given number is 24 then the output should be

Answer 1

I have a solution without recursion or sorting or stacks in C/C++.

#include 
#include 

// For each n, for each i = n-1 to 2, try prod = prod*i, if prod < N.

int
g(int N, int n, int k)
{
        int i = k;
        int prod = n;
        std::vector myvec;

        myvec.push_back(n);
        while (i > 1) {
                if (prod * i == N) {
                        prod = prod*i;
                        myvec.push_back(i);
                        for (auto it = myvec.begin();
                                it != myvec.end(); it++) {
                                std::cout << *it << ",";
                        }
                        std::cout << std::endl;
                        return i;
                } else if (prod * i < N) {
                        prod = prod*i;
                        myvec.push_back(i);
                } else { i--;}
        }

        return k;
}

void
f(int N)
{
        for (int i = 2; i <= N/2; i++) {
                int x = g(N, i, i-1);
                // Extract all possible factors from this point
                while (x > 0) {
                        x = g(N, i, x-1);
                }
        }
}

int
main()
{
        f(24);

        return 0;
}

And output is like this:

$ ./a.out
    3,2,2,2,
    4,3,2,
    6,4,
    6,2,2,
    8,3,
    12,2,