[LeetCode]Factor Combinations

public class Solution {
List<List<Integer>> result = new ArrayList<List<Integer>>();
public List<List<Integer>> getFactors(int n) {
if (n == 1) {
return result;
}
helper(n, new ArrayList<Integer>(), 2);
return result;
}
public void helper(int n, List<Integer> list, int pre) {
if (n == 1) {
if (list.size() > 1)
result.add(list);
return;
}
for (int i = pre; i <= n; i++) {
if (n % i == 0) {
List<Integer> l = new ArrayList<Integer>(list);
l.add(i);
helper(n / i, l, i);
}
}
}
}