Here are some problems we can cover:
Flatten binary tree to linked list in order of preorder traversal Flatten binary tree to linked list in order of inorder traversal Flatten binary search tree to sorted linked list Flatten binary search tree to sorted doubly linked list in-place Flatten Binary Search Tree to Circular Doubly Linked List Convert Sorted Singly Linked List into a Balanced Binary search Tree BST Convert Heap ordered Linked List to Binary Tree Flatten Binary tree to double linked list in-place