public ListNode MergeKLists(ListNode[] lists)
{
switch(lists.Length)
{
case 0:
return null;
case 1:
return lists.First();
default:
var newLists = new ListNode[(lists.Length + 1) / 2];
for (var index = 0; index < lists.Length; index += 2)
{
newLists[index / 2] = index == lists.Length - 1
? lists[index]
: this.Merge2Lists(
lists[index]
, lists[index + 1]);
}
return this.MergeKLists(newLists);
}
}
