Solution: Flatten Binary Tree to Linked List
Understand how to flatten a binary tree into a singly linked list by rearranging nodes in-place using depth-first traversal. Learn to transform the tree so the left child of each node is null and the right child points to the next node in preorder sequence, optimizing space and time complexity.
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: