Using Morris Traversal, we can traverse the tree without using stack and recursion. The idea of Morris Traversal is based on Threaded Binary Tree. In this traversal, we first create links to Inorder successor and print the data using these links, and finally revert the changes to restore original tree.
1. Initialize current as root 
2. While current is not NULL    
If current does not have left child       
a) Print current’s data      
 b) Go to the right, i.e., current = current->right   
 Else      
 a) Make current as right child of the rightmost node in current's left subtree      
 b) Go to this left child, i.e., current = current->left