In-Order Flatten A Binary Tree to Linked List

In-order flatten binary tree, the idea here is similar to in-order traverse of the tree, keep a pointer to previous node visited, then link current node with previous.

public static void FlattenABinaryTreetoLinkedListInOrder(Node root){

Stack<Node> s = new Stack<Node>();

Node c = root;

Node pre = null;

while(!s.isEmpty()||c!=null){

if(c!=null){

s.push(c);

c = c.left;

}

else{

Node n = s.pop();

if(pre!=null){

pre.right = n;

pre.left = null;

}

pre = n;

n = n.right;

}

}

}