[leetcode]做过的题的目录

随着做过的题越来越多，我觉得我需要一个目录来让我飞快的找到题目。

题目名称	难易程度	可考虑的解法
204. Count Primes	Easy	check every number read detals
190. Reverse Bits	Easy	Bit operation
154. Find Minimum in Rotated Sorted Array II	Hard	Binary Search
165. Compare Version Numbers	Medium	compare every sigle number
187. Repeated DNA Sequences	Medium	using map
698. Partition to K Equal Sum Subsets	Medium	DFS / DP
445. Add Two Numbers II	Medium	Using Stack
582. Kill Process	Medium	using queue to help
74. Search a 2D Matrix	Medium	Binary Search
129. Sum Root to Leaf Numbers	Medium	Recursion
199. Binary Tree Right Side View	Medium	Layer traverse
831. Masking Personal Information	Medium	Check every situations
516. Longest Palindromic Subsequence	Medium	Dynamic Programming
251. Flatten 2D Vector	Medium	using iterators
140. Word Break II	hard	memorized searching
296. Best Meeting Point	hard	Hamilton distance read details
450. Delete Node in a BST	Medium	recursion read details
290. Word Pattern	Easy	Using hashmap
266. Palindrome Permutation	Easy	counting the appearance times of characteristics
186. Reverse Words in a String II	Medium	using stack
648. Replace Words	Medium	HashMap
203. Remove Linked List Elements	Easy	check every nodes and recorde previous node
442. Find All Duplicates in an Array	Medium	read details(assign each number to its position
807. Max Increase to Keep City Skyline	Medium	find column maximum and row maximum
433. Minimum Genetic Mutation	Medium	using bfs to test every possible mutation
205. Isomorphic Strings	Easy	using hash-map to store last position
457. Circular Array Loop	Medium	using fast and slow pointers
735. Asteroid Collision	Medium	using vector to store the alive asteroid
722. Remove Comments	Medium	check every character one by one
298. Binary Tree Longest Consecutive Sequence	Medium	recursion
117. Populating Next Right Pointers in Each Node II	Medium	nested loop with pointers (read details)
116. Populating Next Right Pointers in Each Node	Medium	layer traverse by queue
163. Missing Ranges	Medium	traverse the array
727. Minimum Window Subsequence	Hard	DP
336. Palindrome Pairs	Hard	Hash Map
642. Design Search Autocomplete System	Hard	Trie tree with priority queue
65. Valid Number	Hard	DFA
139. Word Break	Medium	DP
489. Robot Room Cleaner	Hard	DFS and store relative position to avoid infinite loop
745. Prefix and Suffix Search	Hard	Trie tree
56. Merge Intervals	Medium	sort and merge
67. Add Binary	Easy	String operation
256. Paint House	Easy	DP
265. Paint House II	Hard	DP
275. H-Index II	Medium	Binary search
410. Split Array Largest Sum	Hard	Greedy and Binary search
88. Merge Sorted Array	Easy	fill spaces back to front
801. Minimum Swaps To Make Sequences Increasing	Medium	DP
764. Largest Plus Sign	Medium	traverse the matrix
865. Smallest Subtree with all the Deepest Nodes	Medium	post-order traverse by recursion
426. Convert Binary Search Tree to Sorted Doubly Linked List	Medium	In-order traverse by iteration
334. Increasing Triplet Subsequence	Medium	read details
639. Decode Ways II	Hard	watch out cornner cases
784. Letter Case Permutation	Easy	change to the same case and then change
68. Text Justification	Hard	read details
109. Convert Sorted List to Binary Search Tree	Meidum	Divide and Conquer
173. Binary Search Tree Iterator	Medium	use stack to help
543. Diameter of Binary Tree	Easy	recursion; read question carefully!!
20. Valid Parentheses	Easy	using stack
269. Alien Dictionary	Hard	Topological sort
554. Brick Wall	Medium	Analyze the questions first! used Map
721. Accounts Merge	Medium	Union Find
824. Goat Latin	Easy	Using stringstream and apply the rule
689. Maximum Sum of 3 Non-Overlapping Subarrays	Hard	Divide it into 3 parts and DP
283. Move Zeroes	Easy	2 pointers
282. Expression Add Operators	Hard	DFS and consider the priority
158. Read N Characters Given Read4 II - Call multiple times	Hard	read Details
210. Course Schedule II	Medium	topological sorting
286. Walls and Gates	Medium	BFS
750. Number Of Corner Rectangles	Medium	taverse with pruning
274. H-Index	Medium	understanding the questions first!
636. Exclusive Time of Functions	Medium	using stack and pointers
477. Total Hamming Distance	Medium	finding the rule in the changing
380. Insert Delete GetRandom O(1)	Medium	map and array, the point is O(1)
825. Friends Of Appropriate Ages	Medium	analysis given inequation
398. Random Pick Index	Medium	reservoir sampling
523. Continuous Subarray Sum	Medium	accumulate sum
525. Contiguous Array	Medium	accumulate sum
332. Reconstruct Itinerary	Medium	use multiset and DFS
323. Number of Connected Components in an Undirected Graph	Medium	build a adjacent list and DFS
249. Group Shifted Strings	Medium	loop with visited
382. Linked List Random Node	Meidum	reservoir sampling
stock系列 121 & 122 & 309 & 714 & 123 & 188	Easy&Medium&Hard	Dp
316. Remove Duplicate Letters	Hard	used map and loop, read detail
289. Game of Life	Medium	traverse and change the value
164. Maximum Gap	Hard	Bucket sort
804. Unique Morse Code Words	Easy	Using set and vectors
220. Contains Duplicate III	Medium	Using sliding windows and maps
335. Self Crossing	Hard	Enum all possible situations
233. Number of Digit One	Hard	Find its patter
179. Largest Number	Medium	Sort by new comparator
229. Majority Element II	Medium	Moore voting
169. Majority Element	Easy	Moore voting
540. Single Element in a Sorted Array	Medium	Binary Search
419. Battleships in a Board	Medium	traverse and judge
150. Evaluate Reverse Polish Notation	Medium	stack
53. Find Minimum in Rotated Sorted Array	Easy	Binary search
319. Bulb Switcher	Medium	observe the previous results and do math
223. Rectangle Area	Medium	do math
479. Largest Palindrome Product	Easy	do math
219. Contains Duplicate II	Easy	map  !!careful!!
438. Find All Anagrams in a String	Easy	sliding window
406. Queue Reconstruction by Height	Medium	analysis the problems
581. Shortest Unsorted Continuous Subarray	Easy	read detail:)
416. Partition Equal D Sum	Medium	DP
124. Binary Tree Maximum Path Sum	Medium	traverse by recursion
240. Search a 2D Matrix II	Medim	Find the special corner as start
160. Intersection of Two Linked Lists	Easy	check from the same length
6. ZigZag Conversion	Medium	find relationships or store in arrays
172. Factorial Trailing Zeroes	Easy	find number of 5
152. Maximum Product Subarray	Medium	using 2(max, min) help array
149. Max Points on a Line	Hard	use map and cal gcd
22. Generate Parentheses	Medium	DFS + limits
328. Odd Even Linked List	Medium	pointers
338. Counting Bits	Meidum	loop with vector
293. Flip Game && 294. Flip Game II	Easy & Medium	back tracking
292. Nim Game	Easy	Game Theory
4. Median of Two Sorted Arrays	Hard	with 2 pointers
209. Minimum Size Subarray Sum	Medium	sliding window
322. Coin Change	Medium	DP
673. Number of Longest Increasing Subsequence	Medium	with 2 record vector read details :)
287. Find the duplicate Number	Meidum	binary search and fast and slow pointer
377. Combination Sum IV	Meidum	DP
89. Gray Code	Medium	details:)
43. Multiply Strings	Medium	use array to store product
143. Reorder List	Medium	break the list into 2 lists, process them
57. Insert Interval	Hard	details :)
76. Minimum Window Substring	Hard	Sliding Window
285. Inorder Successor in BST	Medium	characteristic of BST, or In-order traverse
161. One Edit Distance	Medium	Consider corner situations
311. Sparse Matrix Multiplication	Medium	pre-process one matrix
494. Target Sum	Medium	DFS with memory searching to optimize
670. Maximum Swap	Medium	find the maximum of its right including itself
157. Read N Characters Given Read4	Easy	read detail:)
680. Valid Palindrome II	Easy	optimal bruce force
314. Binary Tree Vertical Order Traversal	Medium	Level order traverse + map
325. Maximum Size Subarray Sum Equals k	Medium	accumulate sum + hashmap
253. Meeting Rooms II	Medium	heap(priority_queue)
621. Task Scheduler	Medium	greedy & queue / mathematics
277. Find the Celebrity	Medium	read details:)
273. Integer to English Words	Hard	use map
301. Remove Invalid Parentheses	Hard	BFS / recursion
128. Longest Consecutive Sequence	Hard	use set
236. Lowest Common Ancestor of a Binary Tree	Medium	PreOrder traverse with stack and pruning
168. Excel Sheet Column Title	Easy	loop and reverse()
127. Word Ladder	Medium	BFS, uses queue and map to help
560. Subarray Sum Equals K	Medium	use map store the times of sum appears
647. Palindromic Substrings	Medium	check every possible
151. Reverse Words in a String	Medium	STL: reverse()
535. Encode and Decode TinyURL	Medium	HashMap + rand()
297. Serialize and Deserialize Binary Tree	Hard	iostream
208. Implement Trie (Prefix Tree)	Medium	Trie tree
146. LRU Cache	Hard	Hashmap + list + iterator
632. Smallest Range	Hard
134. Gas Station	Medium	Greedy
692. Top K Frequent Words	Medium	HashMap+pair
347. Top K Frequent Elements	Medium	HashMap+pair
106. Construct Binary Tree from Inorder and Postorder Traversal	Medium	recursion
105. Construct Binary Tree from Preorder and Inorder Traversal	Medium	recursion
81. Search in Rotated Sorted Array II	Medium	binary search
33. Search in rotated sorted array	Medium	binary search
120. Triangle	Medium
391. Perfect Rectangle	Hard	using the area and 4 points
97. Interleaving String	Hard	dp
45. Jump Game II	Hard	greedy
148. Sort List	Medium	merge sort
59. Spiral Matrix II	Medium
147. Insertion Sort List	Medium	insertion sort
73. Set Matrix Zeroes	Medium
189. Rotate Array	Easy
118. Pascal's Triangle && 119. Pascal's Triangle II	Easy	queue
90. Subsets II	Medium
78. Subsets	Medium
93. Restore IP Addresses	Medium	DFS
71. Simplify Path	Medium	sstream
82. Remove Duplicates from Sorted List II	Medium	pointer
26.Remove Duplicates from Sorted Array	Easy	pointer
95. Unique Binary Search Trees II	Medium	DFS / DP
96. Unique Binary Search Trees	Medium	DP
312. Burst Balloons	Hard	DP（区间DP）
99. Recover Binary Search Tree	Hard	Inorder traverse
98. Validate Binary Search Tree	Medium	Inorder traverse
30. Substring with Concatenation of All Words	Hard	DFS + HashMap
29. Divide Two Integers	Medium	bit operation
443. String Compression	Easy
92. Reverse Linked List II	Medium
114. Flatten Binary Tree to Linked List	Medium	stack
814. Binary Tree Pruning	Medium
324. Wiggle Sort II	Medium
341. Flatten Nested List Iterator	Medium	stack
300. Longest Increasing Subsequence	Medium
72. Edit Distance	Hard	DP
63. Unique Paths II	Medium	DP
221.Maximal Square	Medium
House Robbers. 198 & 213	Medium & Easy	DP
218.The Skyline Problem	Hard	scan line problem: heap
41. First Missing Positive	Hard	interesting method
138. Copy List with Random Pointer	Medium	map / list operation
278. First Bad Version	Easy	binary search
69. Sqrt(x)	Easy	binary search
162. Find Peak Element	Medium	binary search
239. Sliding Window Maximum	Hard	heap/deque
654. Maximum Binary Tree	Medium
85. Maximal Rectangle	hard
36. Valid Sudoku	Medium	record matrix
32. Longest Valid Parentheses	Hard	stack
61. Rotated List	Medium
leetcode栈系列155 & 232 & 349	Easy	stack / 2 stacks
480. Sliding Window Median	Hard	2 heaps
295. Find Median From Data Stream	Hard	2 heaps
84. Large rectangle in histogram	Hard	monotonous stack
34. Search for a Range	Medium
44.wildcard matching	Hard	DP
48. Rotate Image	Medium
49. Group Anagrams	Medium	hashmap
10.Regular Expression Matching	Hard	recursion/DP
25. Reverse Node in k-Group	Hard
Leetcode Combination系列：39 & 77 & 40 & 216 & 17	Medium	DFS
38. Count and Say	Easy
35. search Insert Position	Easy
46.Permutation & 47.Permutation II	Medium	DFS
5 Longest Palindromic Substring	Medium	Manarch / common
12. Integer to Roman	Medium
13. Roman to Integer	Easy	Hash-Map
8. String to Integer	Medium
42. Trapping Rain Water	Hard
407. trapping rain water II	Hard	heap
11. Container with Most Water	Medium
19 Remove Nth Node From End of List	Medium	fast and slow pointers
23. Merge K sorted List	Hard	heap
234. Palindrome Linked List	Easy	stack
142. LinkedList Cycle II	Medium	fast and slow pointers
141.Linked List Cycle 快慢指针	Easy	fast and slow pointers
leetcode Sum合集	Easy & Medium	map
79.word search	Medium	DFS with visited array
261.Graph Valid Tree	Medium	Union Find to find circle
305.Number Of Islands II	Hard	Union Find