关于二叉树的遍历，使用栈递归或者仿栈循环都是需要O(N)的空间，Morris Traversal保证了空间为O(1)，时间还是O(N)（比原来多了一遍）。

Return any binary tree that matches the given preorder and postorder traversals.

Given a binary tree, find the leftmost value in the last row of the tree.

Given the root node of a binary search tree (BST) and a value. You need to find the node in the BST that the node’s value equals the given value. Return the subtree rooted with that node. If such n…

For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees.

Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not.

We are given the head node root of a binary tree, where additionally every node’s value is either a 0 or a 1.