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 node doesn't exist, you should return NULL.

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.