Solution: Flatten Binary Tree to Linked List
Explore how to flatten a binary tree into a linked list by rearranging nodes in preorder traversal order using an optimized depth-first search approach. Understand how to modify the tree in place by updating pointers to create a linear linked list without additional data structures, while considering time and space efficiency.
Statement
Given the root of a binary tree, the task is to flatten the tree into a linked list using the same TreeNode class. The left child pointer of each node in the linked list should always be NULL, and the right child pointer should point to the next node in the linked list. The nodes in the linked list should be in the same order as that of the preorder traversal of the given binary tree.
Constraints: