Question

I have a function it returns prime factors of a number but when I initialize int array I set size.So the result consists unnecessary zeros.How can I return result array without zeros or how can I initialize array applicable size? I am not using Lists

public static int[] encodeNumber(int n){
        int i;
        int j = 0;
        int[] prime_factors = new int[j];
        if(n <= 1) return null;
        for(i = 2; i <= n; i++){
            if(n % i == 0){
                n /= i;
                prime_factors[j] = i;
                i--;
                j++;
            }
        }
        return prime_factors;
    }

Thanx!!!

Answer 1

Allocate as many factors as you think the number may have (32 sounds like a good candidate), and then use Arrays.copyOf() to cut off the array at the actual limit:

return Arrays.copyOf(prime_factors, j);