public RNode Connect(RNode root) //perfect binary tree
{
#region O(1) space
if (root == null || root.left == null)
{
return(root);
}
RNode parent = root;
while (parent.left != null)
{
RNode current = parent;
while (current != null)
{
current.left.next = current.right;
if (current.next != null)
{
current.right.next = current.next.left;
}
current = current.next;
}
parent = parent.left;
}
return(root);
#endregion
}
public RNode(int _val, RNode _left, RNode _right, RNode _next)
{
val = _val;
left = _left;
right = _right;
next = _next;
}
public RNode Connect2(RNode root) // if it is not perfect binary tree -> solve again
{
#region O(N) space
//if (root == null)
// return root;
//Queue<RNode> queue = new Queue<RNode>();
//queue.Enqueue(root);
//while (queue.Count > 0)
//{
// int count = queue.Count;
// RNode prev = null;
// while (count > 0)
// {
// RNode node = queue.Dequeue();
// if (prev != null)
// prev.next = node;
// prev = node;
// if (node.left != null)
// queue.Enqueue(node.left);
// if (node.right != null)
// queue.Enqueue(node.right);
// count--;
// }
//}
//return root;
#endregion
if (root == null)
{
return(root);
}
RNode head = root;
while (head != null)
{
RNode curr = null;
RNode nextLevelHead = null;
while (head != null)
{
if (head.left != null)
{
if (curr == null)
{
curr = head.left;
nextLevelHead = head.left;
}
else
{
curr.next = head.left;
curr = curr.next;
}
}
if (head.right != null)
{
if (curr == null)
{
curr = head.right;
nextLevelHead = head.right;
}
else
{
curr.next = head.right;
curr = curr.next;
}
}
head = head.next;
}
head = nextLevelHead;
}
return(root);
}