CareerCup

You just need to write a recursive method to print the ArrayList

void Print(ArrayList list)
{
    if(list==null || list.Count==0) return;

    for(int i=0;i<list.Count;i++)
    {
        if(list[i] is ArrayList)
            Print((ArrayList)list[i]);
        else
            Output(list[i]);
    }
}

Method Output() is used to print element to screen.

What about an ArrayList [1,2,3] : 2 is also having an Array List of 2 elements while 3 is having 3 more elements..Can you print those out?

You can write an extension method for arraylists, like ToStringX() [unfortunately you cannot override its ToString - at least I think so!]
But this one should work as cl.ToStringX()

public static string ToStringX(this ArrayList array)
        {
            string s = "[";
            foreach (object obj in array)
            {
                ArrayList inner = obj as ArrayList;
                if (inner != null)
                {
                    s += inner.ToStringX() + " ";
                }
                else
                {
                    s += obj.ToString() + " ";
                }
            }
            return s+"]";
        }

foreach (ArrayList i in al)
{
for (int k = 0; k < i.Count ;k++ )
{
Console.Write(i[k]);
}
}

ArrayList al = new ArrayList();
ArrayList bl = new ArrayList();
ArrayList cl = new ArrayList();
al.Add(2);
al.Add(1);
bl.Add(3);
bl.Add(4);

cl.Add(al);
cl.Add(bl);

foreach (ArrayList a in cl) {
foreach (int k in a) {
Console.WriteLine(k);
}

}

add(2)