Mergesort

//Here is an unreadable mergesort done with Lists, but low line count
    public static List<Integer> mergesort(List<Integer> list)
    {
        if(list.size() == 1)
            return list;

        int size = list.size();
        List<Integer> a1 = new ArrayList<Integer>();
        List<Integer> a2 = new ArrayList<Integer>();
        List<Integer> answer = new ArrayList<Integer>();

        for(int i = 0; i < size; i++)
            (i < Math.floor(size/2f)?a1:a2).add(list.get(i));

        a1 = mergesort(a1);
        a2 = mergesort(a2);

        while(!(a1.size() == 0 && a2.size() == 0))
            answer.add((a1.size()==0||a2.size()==0?(a1.size()==0?a2:a1):(a1.get(0)<=a2.get(0)?a1:a2)).remove(0));

        return answer;
    }

//Here is mergesort done with Lists
    public static List<Integer> mergesort(List<Integer> list)
    {
        if(list.size() == 1)
            return list;

        int size = list.size();
        List<Integer> a1 = new ArrayList<Integer>();
        List<Integer> a2 = new ArrayList<Integer>();

        for(int i = 0; i < (int)Math.floor(size/2f); i++)
            a1.add(list.get(i));
        for(int i = (int)Math.ceil(size/2); i < size; i++)
            a2.add(list.get(i));

        List<Integer> b1 = mergesort(a1);
        List<Integer> b2 = mergesort(a2);
        List<Integer> arr2 = new ArrayList<Integer>();
        while(!(b1.size() == 0 && b2.size() == 0))
            if(b1.size() == 0 || b2.size() == 0)
                if(b1.size() == 0)
                    arr2.add(b2.remove(0));
                else
                    arr2.add(b1.remove(0));
            else
                if(b1.get(0) <= b2.get(0))
                    arr2.add(b1.remove(0));
                else
                    arr2.add(b2.remove(0));

        return arr2;
    }


//Here is mergesort done with arrays. Note that I wrote a 'pop' function that this relies on.
    public static int[] mergesort(int[] list)
    {
        int size = list.length;
        if(size == 1)
            return list;

        int[] a1 = new int[(int)Math.floor(size/2f)];
        int[] a2 = new int[(int)Math.ceil (size/2f)];

        int j;

        j = 0;
        for(int i = 0; i < (int)Math.floor(size/2f); i++)
            a1[j++] = list[i];
        j = 0;
        for(int i = (int)Math.ceil(size/2); i < size; i++)
            a2[j++] = list[i];

        int[] b1 = mergesort(a1);
        int[] b2 = mergesort(a2);
        int[] arr2 = new int[size];
        j = 0;
        while(!(b1[0] == Integer.MIN_VALUE && b2[0] == Integer.MIN_VALUE))
            if(b1[0] == Integer.MIN_VALUE || b2[0] == Integer.MIN_VALUE)
                if(b1[0] == Integer.MIN_VALUE)
                    arr2[j++] = (pop(b2));
                else
                    arr2[j++] = (pop(b1));
            else
                if(b1[0] <= b2[0])
                    arr2[j++] = (pop(b1));
                else
                    arr2[j++] = (pop(b2));

        return arr2;
    }
    private static int pop(int[] arr)
    {
        int value = arr[0];
        for(int i = 0; i < arr.length-1; i++)
            arr[i] = arr[i+1];
        arr[arr.length-1] = Integer.MIN_VALUE;
        return value;
    }