//Step1:
// 1---2---3---4---5---6--NULL
// |
// 7---8---9---10--NULL
// |
// 11--12--NULL
//Step2:
//1---2---3---7---8---9---10---4---5---6--NULL
// |
// 11--12--NULL
//Step3:
//1---2---3---7---8---11--12--9---10--4---5---6--NULL
public NodeWithChildren Flatten2(NodeWithChildren head)
{
if (head == null)
{
return(null);
}
NodeWithChildren tmp = head;
while (tmp != null)
{
if (tmp.child != null)
{
NodeWithChildren child = tmp.child;
tmp.child = null;
NodeWithChildren next = tmp.next;
tmp.next = child;
child.prev = tmp;
while (child.next != null)
{
child = child.next;
}
if (next != null)
{
child.next = next;
next.prev = child;
}
}
tmp = tmp.next;
}
return(head);
}
// Step1:
// 1---2---3---4---5---6--NULL
// |
// 7---8---9---10--NULL
// |
// 11--12--NULL
// Step2:
// 1---2---3---4---5---6--NULL
// |
// 7---8---11--12--9---10--NULL
// Step3:
// 1---2---3---7---8---11--12--9---10--4---5---6--NULL
public static NodeWithChildren Flatten(NodeWithChildren head)
{
if (head == null)
{
return(head);
}
NodeWithChildren tmp = head;
while (tmp != null)
{
if (tmp.child != null)
{
NodeWithChildren child = Flatten(tmp.child);
tmp.child = null;
NodeWithChildren next = tmp.next;
tmp.next = child;
child.prev = tmp;
while (child.next != null)
{
child = child.next;
}
child.next = next;
if (next != null)
{
next.prev = child;
}
tmp = next;
}
else
{
tmp = tmp.next;
}
}
return(head);
}
public NodeWithChildren FlattenAndReturnTail(NodeWithChildren head)
{
if (head == null)
{
return(null);
}
if (head.child == null)
{
if (head.next == null)
{
return(head);
}
return(FlattenAndReturnTail(head.next));
}
else
{
NodeWithChildren child = head.child;
head.child = null;
NodeWithChildren next = head.next;
NodeWithChildren childTail = Flatten(child);
head.next = child;
child.prev = head;
if (next != null)
{
childTail.next = next;
next.prev = childTail;
return(FlattenAndReturnTail(next));
}
return(childTail);
}
}
public static void PrintFlatList(NodeWithChildren head)
{
if (head == null)
{
Console.Write("Null head");
}
NodeWithChildren tmp = head;
while (tmp.next != null)
{
Console.Write(tmp.key + "---");
tmp = tmp.next;
}
Console.Write("null");
return;
}
public NodeWithChildren(int key)
{
this.key = key;
prev = next = null;
child = null;
}
public NodeWithChildren Flatten3(NodeWithChildren head)
{
FlattenAndReturnTail(head);
return(head);
}