Transformations Between Binary Tree Structuctures and Linked Lists

Problem

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-preorder-traversal) [Flatten binary tree to linked list in order of inorder 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-linked-list) [Flatten binary search tree to sorted doubly linked list in-place](convert-binary-search-tree-to-sorted-doubly-linked-list) [Flatten Binary Search Tree to Circular Doubly Linked List](flatten-binary-search-tree-to-circular-doubly-linked-list) [Convert Sorted Singly Linked List into a Balanced Binary search Tree BST](convert-sorted-list-into-a-height-balanced-binary-search-tree) [Convert Heap ordered Linked List to Binary Tree](convert-heap-ordered-linked-list-to-binary-tree) [Flatten Binary tree to double linked list in-place](flatten-binary-tree-to-double-linked-list-in-place)