algorithm for removing common elements from different lists in the program below

Question

This is the code for evaluating factors of given integer array. The problem is I need to find LCM from the list I have received as output. Suggest something for removing duplicate elements from list

Main method

public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int [] ar = {6,12,36};
        for (int a:
             ar) {
            System.out.println(getFactor(a));
        }

getFactor(long) returns the list of factors

private static List<Integer> getFactor(long n) {
        List<Integer> l = new ArrayList<>();
        for (int i=2;n!=1;i++)
        {
            if(n%i==0)
            {
                l.add(i);
                n=n/i;
                i=1;
            }
        }
        return l;
    }

/*Input
6,12,36
Output
[2, 3]
[2, 2, 3]
[2, 2, 3, 3]*/

Problem remove the [2,3] duplicates from other lists to get LCM(Least Common Multiple).

Answer 1

No where in your code you're calculating the lcm. All I see is you have found the factors of three numbers.

[2, 3]   -> Factors of 6
[2, 2, 3] -> Factors of 12
[2, 2, 3, 3] -> -> Factors of 6

You'll have to write another function to calculate the lcm.

Answer 2

Suggest something for removing duplicate elements from list

Use Set instead of a List

private static Set<Integer> getFactor(long n) {
    Set<Integer> l = new HashSet<>();
    for (int i = 2; n != 1; i++) {
        if (n % i == 0) {
            l.add(i);
            n = n / i;
            i = 1;
        }
    }
    return l;
}

Output:

[2, 3]
[2, 3]
[2, 3]

Recommended reading: What is the difference between Set and List?