public Node1(int _val, Node1 _left, Node1 _right, Node1 _next)
{
val = _val;
left = _left;
right = _right;
next = _next;
}
//TC - O(N)
//SC - O(1), no space
public Node1 Connect2(Node1 root)
{
if (root == null)
{
return(root);
}
Node1 leftMost = root;
while (leftMost.left != null)
{
Node1 head = leftMost;
while (head != null)
{
//Condition 1: for two childs of same parent Node1
head.left.next = head.right;
//condition 2: right child of Node11 and left child of Node11's sibling(Node12)
if (head.next != null)
{
head.right.next = head.next.left;
}
head = head.next;
}
leftMost = leftMost.left;
}
return(root);
}
/**************************************II- Binary Tree with missing Nodes********************************************************/
//TC - O(N)
//SC - O(N)
//USING BFS Level ORDER
//SAME AS Connect above, useing q and adding connection of the Dequeue nodes
//TC - O(N)
//SC - O(1)
public Node1 ConnectII_I(Node1 root)
{
if (root == null)
{
return(root);
}
//head node for return purpose only
Node1 head = root;
//dummy will maintain the child level order connections
Node1 dummy = new Node1(0);
Node1 pre = dummy;
//processing on root
while (root != null)
{
//if left exists then add it to pre
if (root.left != null)
{
pre.next = root.left;
pre = pre.next;
}
//if right exists add it to the pre whcih alreay have left init
if (root.right != null)
{
pre.next = root.right;
pre = pre.next;
}
root = root.next;
//if root is null which means the that level is end, so move root to next node of dummy(make null)
if (root == null)
{
//reset all
pre = dummy;
root = dummy.next;
dummy.next = null;
}
}
return(head);
}
//TC - O(N)
//SC - O(N)
//USING BFS Level ORDER
public Node1 Connect(Node1 root)
{
if (root == null)
{
return(root);
}
Queue <Node1> q = new Queue <Node1>();
q.Enqueue(root);
while (q.Count > 0)
{
int size = q.Count;
for (int i = 0; i < size; i++)
{
Node1 Node1 = q.Dequeue();
if (i < size - 1)//i should be less than size to access the same level Node1s in the q
{
Node1.next = q.Peek();
}
if (Node1.left != null)
{
q.Enqueue(Node1.left);
}
if (Node1.right != null)
{
q.Enqueue(Node1.right);
}
}
}
return(root);
}