Merge One Sorted Array Into Another Solution 2

    static ArrayList<Integer> merge_one_into_another(ArrayList<Integer> arr1, ArrayList<Integer> arr2) {
        int i = arr1.size()-1;
        int j = arr1.size()-1;
        int idx = arr2.size()-1;

        // sorting from right side
        while(i >= 0 && j >= 0)  {
            if(arr1.get(i) >= arr2.get(j)) {
                arr2.set(idx, arr1.get(i));
                arr1.set(i, 0);
                i--;
                idx--;
            } else {
                arr2.set(idx, arr2.get(j));
                arr2.set(j, 0);
                 j--;
                 idx--;
            }
        }
        // put remaining elements in arr1 to arr2
        while(i >= 0)
        {
            arr2.set(idx, arr1.get(i));
            arr1.set(i, 0);
            i--;
            idx--;
        }

        return arr2;
    }