James Pan

原题网址：https://leetcode.com/problems/delete-node-in-a-bst/Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly up

原题网址：https://leetcode.com/problems/binary-tree-postorder-traversal/Given a binary tree, return the postorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1

原题网址：https://leetcode.com/problems/palindrome-pairs/Given a list of unique words. Find all pairs of distinct indices (i, j) in the given list, so that the concatenation of the two words, i.e.

原题网址：https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right

原题网址：https://leetcode.com/problems/binary-tree-level-order-traversal/Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).For

原题网址：https://leetcode.com/problems/symmetric-tree/Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric:

原题网址：https://leetcode.com/problems/same-tree/Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identic

原题网址：https://leetcode.com/problems/validate-binary-search-tree/Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtre

原题网址：https://leetcode.com/problems/unique-binary-search-trees/Given n, how many structurally unique BST's (binary search trees) that store values 1...n?For example,Given n = 3, there are a

原题网址：https://leetcode.com/problems/unique-binary-search-trees-ii/Given n, generate all structurally unique BST's (binary search trees) that store values 1...n.For example,Given n = 3, your

原题网址：https://leetcode.com/problems/scramble-string/Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.Below is one possible

原题网址：https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.方法：使用慢指针

原题网址：https://leetcode.com/problems/binary-tree-inorder-traversal/Given a binary tree, return the inorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1

原题网址：https://leetcode.com/problems/data-stream-as-disjoint-intervals/Given a data stream input of non-negative integers a1, a2, ..., an, ..., summarize the numbers seen so far as a list of dis

原题网址：https://leetcode.com/problems/serialize-and-deserialize-bst/Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file

原题网址：https://leetcode.com/problems/path-sum-iii/You are given a binary tree in which each node contains an integer value.Find the number of paths that sum to a given value.The path does

原题网址：https://leetcode.com/problems/binary-tree-upside-down/Given a binary tree where all the right nodes are either leaf nodes with a sibling (a left node that shares the same parent node) or em

红黑树的两种基本操作做旋转和右旋转，LEFT_ROTATE(x)和RIGHT_ROTATE(x)分别表示以x为支点进行左旋转和右旋转。红黑树的插入操作以插入点为当前点（z），检查是否满足红黑树规则，如果不满足则调整，直至完全满足为止。根据当前点z的父节点和叔叔节点的颜色，可以分为均为红色以及叔叔节点为黑色的情况，而根据当前节点是父节点的做节点还是右节点分为两种情况。

原题网址：https://leetcode.com/problems/find-leaves-of-binary-tree/Given a binary tree, find all leaves and then remove those leaves. Then repeat the previous steps until the tree is empty.Example:

原题网址：https://leetcode.com/problems/remove-duplicate-letters/Given a string which contains only lowercase letters, remove duplicate letters so that every letter appear once and only once. You mus

原题网址：https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree/One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record t

原题网址：https://leetcode.com/problems/minimum-height-trees/For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all po

原题网址：https://leetcode.com/problems/recover-binary-search-tree/Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A sol

原题网址：https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/Follow up for problem "Populating Next Right Pointers in Each Node".What if the given tree could be any bina

原题网址：https://leetcode.com/problems/binary-tree-maximum-path-sum/Given a binary tree, find the maximum path sum.For this problem, a path is defined as any sequence of nodes from some starting

原题网址：https://leetcode.com/problems/house-robber-iii/The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root,

原题网址：https://leetcode.com/problems/populating-next-right-pointers-in-each-node/Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkN

原题网址：https://leetcode.com/problems/flatten-binary-tree-to-linked-list/Given a binary tree, flatten it to a linked list in-place.For example,Given 1 / \ 2 5

原题网址：https://leetcode.com/problems/path-sum-ii/Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.For example:Given the below binary tree

原题网址：https://leetcode.com/problems/path-sum/Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

原题网址：https://leetcode.com/problems/balanced-binary-tree/Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as a binary tree in

原题网址：https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/Given an array where elements are sorted in ascending order, convert it to a height balanced BST.方法：递归，自顶向下。/** *

原题网址：https://leetcode.com/problems/binary-tree-level-order-traversal-ii/Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by le

原题网址：https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume

原题网址：https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume t

原题网址：https://leetcode.com/problems/maximum-depth-of-binary-tree/Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node

原题网址：https://leetcode.com/problems/graph-valid-tree/Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to check whether these

原题网址：https://leetcode.com/problems/binary-search-tree-iterator/Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.Calling ne

原题网址：https://leetcode.com/problems/closest-binary-search-tree-value-ii/Given a non-empty binary search tree and a target value, find k values in the BST that are closest to the target.Note:

原题网址：https://leetcode.com/problems/largest-bst-subtree/Given a binary tree, find the largest subtree which is a Binary Search Tree (BST), where largest means subtree with largest number of nodes