[LeetCode]Unique BST

[LeetCode]Convert Sorted List to BST

[LeetCode]Convert Sorted Array to BST

[LeetCode]Construct Binary Tree from Inorder and Postorder Traversal

[LeetCode]Construct Binary Tree from Inorder and Preorder Traversal

[LeetCode]Merge Interval

[LeetCode]Insert Interval

[LeetCode]LRU Cache

[LeetCode]Search for a Range

[LeetCode]Find Median in Two Sorted Array

[Data Structure]Union Find

[Data Structure]Trie

[LeetCode]Word Ladder

[LeetCode]Maximal Rectangle

[Algorithm]Maximum and Minimum in Window of Numbers

[Algorithm]Hill

[Algorithm]Reorder Array

[LeetCode]Best Time to Buy and Sell Stock IV

[LeetCode]Best Time to Buy and Sell Stock II

[LeetCode]Best Time to Buy and Sell Stock III

[LeetCode]Best Time to Buy and Sell Stock

[LintCode]Maximum Subarray III

[LintCode]Maximum Subarray Difference

[LintCode]Minimum Subarray

[LintCode]Maximum Subarray II

[LeetCode]Maximum Subarray

[Java]Polymorphism

[LeetCode]Candy

[LeetCode]Container with Most Water

[Algorithm]Trapping Rain Water II

[LeetCode]Trapping Rain Water

[LeetCode]Largest Rectangle in Histogram

[Java]Reusing Classes

[Java]Access Control

[Algorithm]First Non Repeating Character

[Algorithm]Get Distance Between Two Nodes in Binary Tree

[LintCode]Lowest Common Ancestor

[Algorithm]Get Max Distance in Binary Tree

[Algorithm] Flatten Binary Tree to Doubly Linked List As Postorder

[Algorithm] Flatten Binary Tree to Doubly Linked List As Inorder

[Algorithm] Flatten Binary Tree to Doubly Linked List As Preorder

[LeetCode] Flatten Binary Tree to Linked List

[LeetCode]Longest Substring with At Most Two Distinct Characters

[LeetCode]Longest Substring Without Repeating Characters

[LeetCode]Minimum Window Substring

[LeetCode]Substring with Concatenation of All Words

[LeetCode]Merge k Sorted Lists

[LeetCode]Balanced Binary Tree

[Algorithm]Get Paths with Given Sum in Binary Tree

[Algorithm]Get Path with Max Sum in Binary Tree

[LeetCode]Word Break II

[LeetCode]Word Break

[LeetCode]Partition List

[LeetCode]Merge Two Sorted Lists

[LeetCode]Remove Duplicates from Sorted List II

[LeetCode]Remove Duplicates from Sorted List

[LeetCode]Remove Nth Node From End of List

[LeetCode]Reorder List

[LeetCode]Reverse Linked List II

[LeetCode]Rotate List

[LeetCode]Sort List

[LeetCode]Swap Nodes in Pairs

[LeetCode]Sqrt

[LeetCode]Divide Two Integers

[LeetCode]Pow(x,n)

[LeetCode]Find Peak Element

[Algorithm]Find Minimum in Rotated Sorted Array(sorted as from max to min)

[LeetCode]Search in Rotated Sorted Array II

[LeetCode]Search in Rotated Sorted Array

[LeetCode]Search Insert Position

[LeetCode]Climbing Stairs

[LeetCode]Binary Zigzag Level Order Traversal

[LeetCode]Binary Tree Level Order Traversal II

[LeetCode]Binary Tree Level Order Traversal

[LintCode]Serialization and Deserialization Of Binary Tree

[Interview]Zillow Coding Test

[Data Structure]Binary Search Tree

本文主要涉及BST的构造以及order operation方面的内容：

[LintCode]Search Range In Binary Search Tree

首先是brute-force的方法， inorder看是不是在range里，在的话就加入。时间复杂度是O(N)。显然面试官不可能希望这个方法。

[LintCode]Remove Node in Binary Search Tree

删除的时候三种情况：

• 没有子节点
• 有一个子节点
• 有两个子节点

[LintCode]Insert Node in Binary Search Tree

很简单题，每个node决定是往左还是往右还是就是这个节点。类似二分的做法。

[LeetCode]String to Integer(atoi)

主要麻烦的地方在于注意各种corner case，按照题目要求来就好。主要讲一下，判断overflow, 之前我用的是很蠢的判断溢出的方法，以正数为例，之前是Integer.MAX_VALUE减去十次原来的数，在减去新的一位看是不是大于0。刷第三次的时候觉得这个方法太过于愚蠢了，稍微想了下，只需要Integer.MAX_VALUE减去新的那一位再除以10，看是不是大于原来的数就可以了。

[LeetCode]Symmetric Tree

Top-down, 尾递归。

[LeetCode]Same Tree

Top-down, 尾递归。

[LeetCode]Validate Binary Search Tree

注意光判断左子结点小于当前节点右子结点大于当前节点是不够的。比如                  5
                                                                                                                                    /  \
                                                                                                                                  3    8
                                                                                                                                    \
                                                                                                                                     6
就满足条件但不是valid BST。要判断也应该是左子树最大值小于当前节点，右子树最小值大于当前节点。不过这样太麻烦，用top-bottom的方法，开始的范围是(－∞，＋∞)。每次经过一个结点从(low, high)分割成(low, curr.val)和(curr.val, high)像两个子节点递归。不满足就返回false，碰到null返回true。

[LeetCode]Binary Search Tree Iterator

BST中序遍历的迭代器，Inorder遍历iterative版本的好处就体现出来了，我们可以控制停在哪里，而recursive版本的就不好控制。这里我们要决定的是如何找到后继结点，分两种情况，一种是有右子树，那么我们找到右子树最小值即可。第二种是没有右子树，我们pop出栈顶的元素就是后继结点，至于为什么，我们在Binary Tree Preorder Traversal已经证明过这个问题。最后注意一下终止条件即可。

[Algorithm]Binary Tree Morris Traversal

Binary Tree的Traversal问题总是面试的重点。不管是recursive还是iterative的版本，我们都需要额外的空间。

[LeetCode]Binary Tree Postorder Traversal

之前在Binary Tree Preorder Traversal中说过，preorder和inorder的方法不适于Postorder因为不方便模拟第三次对节点的访问，所以只好改变方法。

[LeetCode]Binary Tree Inorder Traversal

在Binary Tree Preorder Traversal中说明过，Inorder的代码基本上是一样的，只有一行的区别。

[LeetCode]Binary Tree Preorder Traversal

BST遍历的问题，很经典的问题。