- 627 Longest Palindrome
- 13 Implement strStr()
- 415 Valid Palindrome
- 200 Longest Palindromic Substring
- 891 Valid Palindrome II
- 127 Topological Sorting ***!!!阅读全文并背诵：）
- 615 Course Schedule
- 616 Course Schedule II
- 433 Number of Islands
- 69 Binary Tree Level Order Traversal
- 611 Knight Shortest Path
- 137 Clone Graph
- 605 Sequence Reconstruction ***!!! 反复练习
- 7 Serialize and Deserialize Binary Tree ***!!! 复习反序列化
- 120 Word Ladder ***!!! 反复练习
- 458 Last Position of Target
- 460 Find K Closest Elements 二分法加双指针
- 585 Maximum Number in Mountain Sequence
- 159 Find Minimum in Rotated Sorted Array
- 75 Find Peak Element
- 74 First Bad Version
- 14 First Position of Target
- 141 Sqrt(x)
- 183 Wood Cut
- 447 Search in a big sorted array
- 428 Pow(x, n)
- 140 Fast Power ***!!! recursion or binary earch
- 62 Search in Rotated Sorted Array
- 97 Maximum Depth of Binary Tree
- 66 Binary Tree Preorder Traversal
- 67 Binary Tree Inorder Traversal
- 68 Binary Tree Postorder Traversal
- 93 Balanced Binary Tree
- 95 Validate Binary Search Tree ***!!! 多种方法，反复练习DFS几种二叉树遍历写法
- 596 Minimum Subtree
- 480 Binary Tree Paths
- 453 Flatten Binary Tree to Linked List ***!!! 分治法和遍历法 D&Q || traversal Recursion 递归操作
- 902 Kth Smallest Element in a BST ***!!! 反复练习
- 900 Closest Binary Search Tree Value
- 901 Closest Binary Search Tree Value II ***!!! 反复练习 很难理解
- 578 Lowest Common Ancestor III ***!!! 反复练习 很难理解
- 86 Binary Search Tree Iterator ***!!! 反复练习 复习二叉查找树以及遍历的相关规则
- 521 Remove Duplicate Numbers in Array
- 604 Window Sum
- 610 Two Sum - Difference equals to target ***!!! 枚举，Lambda, 同向指针
- 228 Middle of Linked List
- 102 Linked List Cycle
- 103 Linked List Cycle II ***!!! Just Remember
- 5 Kth Largest Element 快速选择排序
- 148 Sort Colors 三指针算法
- 607 Two Sum III - Data structure design
- 539 Move Zeroes
- 608 Two Sum II - Input array is sorted
- 228 Middle of Linked List
- 464 Sort Integers II ***!!! 多方法
- 143 Sort Colors II ***!!! 同时参考答案解法
- 57 3Sum ***!!! 不熟练
- 31 Partition Array
- 56 two sum
- 17 Subsets
- 18 Subsets II
- 680 Split String
- 425 Letter Combinations of a Phone Number
- 135 Combination Sum
- 153 Combination Sum II
- 33 N-Queens ***!!! 反复练习 很难理解
- 829 Word Pattern II (Not Done)
- 121 Word Ladder II (Not Done)
- 15 Permutations 递归的时候变量都保存在栈里，result里面存的是l_output的地址。但是，当递归函数运行结束，l_output就被pop掉了
- 224 Implement Three Stacks by Single Array (Not Done)
- 494 Implement Stack by Two Queues （Just fllow demo)
- 495 Implement Stack （Just fllow demo)