README.md

Java Algorithm Problems

程序员的一天

从开始这个Github已经有将近两年时间, 很高兴这个repo可以帮到有需要的人. 我一直认为, 知识本身是无价的, 因此每逢闲暇, 我就会来维护这个repo, 给刷题的朋友们一些我的想法和见解. 下面来简单介绍一下这个repo:

README.md: 所有所做过的题目

ReviewPage.md: 所有题目的总结和归纳（不断完善中）

KnowledgeHash2.md: 对所做过的知识点的一些笔记

SystemDesign.md: 对系统设计的一些笔记

Future Milestone: 我准备将一些有意思的题目，做成视频的形式给大家参考

希望大家学习顺利, 对未来充满希望(程序员也是找到好老板的!) 有问题可以给我写邮件([email protected]), 或者在GitHub上发issue给我.

Squence	Problem	Level	Language	Tags	Video Tutorial
0	Alien Dictionary.java	Hard	Java	[]
1	Anagrams.java	Medium	Java	[]
2	Binary Representation.java	Hard	Java	[]
3	Binary Tree Inorder Traversal.java	Easy	Java	[]
4	Binary Tree Level Order Traversal II.java	Medium	Java	[]
5	Binary Tree Level Order Traversal.java	Medium	Java	[]
6	Binary Tree Longest Consecutive Sequence.java	Medium	Java	[]
7	Binary Tree Maximum Path Sum II.java	Medium	Java	[]
8	Binary Tree Path Sum.java	Easy	Java	[]
9	Binary Tree Postorder Traversal.java	Easy	Java	[]
10	Binary Tree Preorder Traversal.java	Easy	Java	[]
11	Binary Tree Right Side View.java	Medium	Java	[]
12	Binary Tree Serialization.java	Medium	Java	[]
13	Binary Tree Zigzag Level Order Traversal.java	Medium	Java	[]
14	Building Outline.java	Hard	Java	[]
15	Change to Anagram.java	Easy	Java	[]
16	Classical Binary Search.java	Easy	Java	[]
17	Climbing Stairs.java	Easy	Java	[]
18	Closest Binary Search Tree Value.java	Easy	Java	[]
19	Closest Number in Sorted Array.java	Easy	Java	[]
20	ColorGrid.java	Medium	Java	[]
21	Combination Sum II.java	Medium	Java	[]
22	Combination Sum.java	Medium	Java	[]
23	Combinations.java	Medium	Java	[]
24	Compare Strings.java	Easy	Java	[]
25	Complete Binary Tree.java	Easy	Java	[]
26	Construct Binary Tree from Inorder and Postorder Traversal.java	Medium	Java	[]
27	Container With Most Water.java	Medium	Java	[]
28	Contains Duplicate II.java	Easy	Java	[]
29	Contains Duplicate III.java	Medium	Java	[]
30	Contains Duplicate.java	Easy	Java	[]
31	Convert Binary Search Tree to Doubly Linked List.java	Medium	Java	[]
32	Convert Expression to Polish Notation.java	Hard	Java	[]
33	Convert Expression to Reverse Polish Notation.java	Hard	Java	[]
34	Convert Integer A to Integer B.java	Easy	Java	[]
35	Copy List with Random Pointer.java	Medium	Java	[]
36	Cosine Similarity.java	Easy	Java	[]
37	Count 1 in Binary.java	Easy	Java	[]
38	Count and Say.java	Easy	Java	[]
39	Count of Smaller Number before itself.java	Hard	Java	[]
40	Count of Smaller Number.java	Medium	Java	[]
41	Count Primes.java	Easy	Java	[]
42	Course Schedule II.java	Medium	Java	[]
43	Course Schedule.java	Medium	Java	[]
44	Data Stream Median.java	Hard	Java	[]
45	Delete Digits.java	Medium	Java	[]
46	Delete Node in the Middle of Singly Linked List.java	Easy	Java	[]
47	Encode and Decode Strings.java	Medium	Java	[]
48	ExcelSheetColumnNumber .java	Easy	Java	[]
49	Expression Evaluation.java	Hard	Java	[]
50	Expression Tree Build.java	Hard	Java	[]
51	Fast Power.java	Medium	Java	[]
52	Fibonacci.java	Easy	Java	[]
53	Find Peak Element II.java	Review	Java	[]
54	Find the Connected Component in the Undirected Graph.java	Medium	Java	[]
55	Find the Weak Connected Component in the Directed Graph.java	Medium	Java	[]
56	First Missing Positive.java	N/A	Java	[]
57	Flatten 2D Vector.java	Medium	Java	[]
58	Flip Game II.java	Medium	Java	[]
59	Flip Game.java	Easy	Java	[]
60	Fraction to Recurring Decimal.java	Medium	Java	[]
61	Game of Life.java	N/A	Java	[]
62	Gas Station.java	N/A	Java	[]
63	Generate Parentheses.java	Medium	Java	[]
64	Gray Code.java	Medium	Java	[]
65	Group Anagrams.java	Medium	Java	[]
66	Group Shifted Strings.java	Easy	Java	[]
67	H-Index II.java	Medium	Java	[]
68	H-Index.java	Medium	Java	[]
69	Hamming Distance.java	Easy	Java	[]
70	Happy Number.java	Easy	Java	[]
71	Hash Function.java	Easy	Java	[]
72	HashHeap.java	Hard	Java	[]
73	HashWithArray.java	Easy	Java	[]
74	HashWithCustomizedClass(LinkedList).java	Medium	Java	[]
75	Heapify.java	Medium	Java	[]
76	Heaters.java	Easy	Java	[]
77	House Robber III.java	Hard	Java	[]
78	Identical Binary Tree.java	Easy	Java	[]
79	Implement Queue by Two Stacks.java	N/A	Java	[]
80	Implement Queue using Stacks.java	Easy	Java	[]
81	Implement Stack by Two Queues.java	Easy	Java	[]
82	Implement Stack using Queues.java	Easy	Java	[]
83	Implement Stack.java	Easy	Java	[]
84	Implement strStr().java	N/A	Java	[]
85	Implement Trie (Prefix Tree).java	Medium	Java	[]
86	Implement Trie.java	Medium	Java	[]
87	IndexMatch.java	Easy	Java	[]
88	Inorder Successor in Binary Search Tree.java	Medium	Java	[]
89	Insert Interval.java	Easy	Java	[]
90	Insert Node in a Binary Search Tree .java	Easy	Java	[]
91	Insertion Sort List.java	N/A	Java	[]
92	Integer to English Words.java	N/A	Java	[]
93	Interleaving Positive and Negative Numbers.java	N/A	Java	[]
94	Intersection of Two Arrays.java	Easy	Java	[]
95	Intersection of Two Linked Lists.java	Easy	Java	[]
96	Interval Minimum Number.java	Medium	Java	[]
97	Interval Sum II.java	Hard	Java	[]
98	Interval Sum.java	Medium	Java	[]
99	Invert Binary Tree.java	Easy	Java	[]
100	Isomorphic Strings.java	Easy	Java	[]
101	Jump Game II.java	Hard	Java	[]
102	Kth Largest Element.java	Medium	Java	[]
103	Kth Smallest Element in a BST.java	N/A	Java	[]
104	Kth Smallest Sum In Two Sorted Arrays.java	Hard	Java	[]
105	Largest Number.java	N/A	Java	[]
106	Largest Rectangle in Histogram.java	N/A	Java	[]
107	Last Position of Target.java	N/A	Java	[]
108	Length of Last Word.java	N/A	Java	[]
109	Longest Common Prefix.java	Medium	Java	[]
110	Longest Common Substring.java	N/A	Java	[]
111	Longest Consecutive Sequence.java	N/A	Java	[]
112	Longest Increasing Continuous subsequence II.java	N/A	Java	[]
113	Longest Increasing Continuous subsequence.java	Easy	Java	[]
114	Longest Palindromic Substring.java	Medium	Java	[]
115	Longest Univalue Path.java	Easy	Java	[]
116	Longest Word in Dictionary.java	Easy	Java	[]
117	Longest Words.java	N/A	Java	[]
118	Lowest Common Ancestor II.java	Easy	Java	[]
119	Lowest Common Ancestor of a Binary Search Tree.java	Medium	Java	[]
120	Lowest Common Ancestor.java	Easy	Java	[]
121	LRU Cache.java	Hard	Java	[]
122	Majority Number II.java	Medium	Java	[]
123	Majority Number III.java	Medium	Java	[]
124	Matrix Zigzag Traversal.java	Easy	Java	[]
125	Max Area of Island.java	Easy	Java	[]
126	Max Tree.java	Hard	Java	[]
127	Maximal Square.java	Medium	Java	[]
128	Maximum Average Subarray II.java	Review	Java	[]
129	Maximum Depth of Binary Tree.java	Easy	Java	[]
130	Maximum Subarray III.java	N/A	Java	[]
131	Maximum Subarray.java	Easy	Java	[]
132	Maximum SubarrayII.java	N/A	Java	[]
133	MaximumSubarrayII.java	N/A	Java	[]
134	Median of two Sorted Arrays.java	Hard	Java	[]
135	Median.java	N/A	Java	[]
136	Meeting Rooms II.java	Medium	Java	[]
137	Meeting Rooms.java	Easy	Java	[]
138	Merge Intervals.java	Easy	Java	[]
139	Merge k Sorted Arrays.java	Medium	Java	[]
140	Merge k Sorted Lists.java	Medium	Java	[]
141	Merge Sorted Array II.java	N/A	Java	[]
142	Merge Sorted Array.java	Easy	Java	[]
143	Merge Two Binary Trees.java	Easy	Java	[]
144	Merge Two Sorted Lists.java	Easy	Java	[]
145	Middle of Linked List.java	N/A	Java	[]
146	Min Stack.java	Easy	Java	[]
147	Minimum Absolute Difference in BST.java	Easy	Java	[]
148	Minimum Height Trees.java	N/A	Java	[]
149	Minimum Path Sum.java	N/A	Java	[]
150	Minimum Subarray.java	N/A	Java	[]
151	MinimumDepthOfBinaryTree.java	Easy	Java	[]
152	Missing Ranges.java	N/A	Java	[]
153	Multiply Strings.java	Medium	Java	[]
154	Next Permutation.java	Medium	Java	[]
155	Nim Game.java	Easy	Java	[]
156	NQueens.java	N/A	Java	[]
157	NQueensII.java	N/A	Java	[]
158	Nth to Last Node in List.java	N/A	Java	[]
159	Number of Airplane in the sky.java	Medium	Java	[]
160	Number Triangles.java	N/A	Java	[]
161	O(1) Check Power of 2.java	N/A	Java	[]
162	One Edit Distance.java	Medium	Java	[]
163	Paint Fence.java	N/A	Java	[]
164	Palindrome Linked List.java	N/A	Java	[]
165	Palindrome Partitioning.java	N/A	Java	[]
166	Palindrome Permutation II.java	Medium	Java	[]
167	Palindrome Permutation.java	Easy	Java	[]
168	Partition Array by Odd and Even.java	N/A	Java	[]
169	Partition Array.java	N/A	Java	[]
170	Partition List.java	N/A	Java	[]
171	Pascal's Triangle II.java	Easy	Java	[]
172	Peeking Iterator.java	N/A	Java	[]
173	Permutation Index.java	Easy	Java	[]
174	Permutation Sequence.java	Medium	Java	[]
175	Permutations II.java	Medium	Java	[]
176	Permutations.java	Medium	Java	[]
177	Populating Next Right Pointers in Each Node II.java	Hard	Java	[]
178	Product of Array Exclude Itself.java	N/A	Java	[]
179	QuickSort.java	Easy	Java	[]
180	Recover Rotated Sorted Array.java	N/A	Java	[]
181	Rehashing.java	Medium	Java	[]
182	Remove Duplicates from Sorted Array.java	Easy	Java	[]
183	Remove Duplicates from Sorted List II.java	N/A	Java	[]
184	Remove Duplicates from Sorted List.java	Easy	Java	[]
185	Remove Duplicates from Unsorted List.java	N/A	Java	[]
186	Remove Invalid Parentheses.java	Hard	Java	[]
187	Remove Linked List Elements.java	N/A	Java	[]
188	Remove Node in Binary Search Tree.java	Hard	Java	[]
189	Reorder List.java	N/A	Java	[]
190	Reshape the Matrix.java	Easy	Java	[]
191	Restore IP Addresses.java	N/A	Java	[]
192	Reverse Integer.java	Easy	Java	[]
193	Reverse Linked List II .java	N/A	Java	[]
194	Reverse Linked List.java	Easy	Java	[]
195	Reverse String.java	Easy	Java	[]
196	Reverse Words in a String II.java	Medium	Java	[]
197	Reverse Words in a String.java	Medium	Java	[]
198	reverseInteger.java	Easy	Java	[]
199	Roman to Integer.java	Easy	Java	[]
200	Rotate Image.java	Medium	Java	[]
201	Rotate List.java	N/A	Java	[]
202	Rotate String.java	N/A	Java	[]
203	Russian Doll Envelopes.java	N/A	Java	[]
204	Search a 2D Matrix II.java	N/A	Java	[]
205	Search a 2D Matrix.java	N/A	Java	[]
206	Search for a Range.java	N/A	Java	[]
207	Search Insert Position.java	N/A	Java	[]
208	Search Range in Binary Search Tree .java	Medium	Java	[]
209	Search Rotated in Sorted Array II.java	N/A	Java	[]
210	Search Rotated in Sorted Array.java	Hard	Java	[]
211	Segment Tree Build II.java	Medium	Java	[]
212	Segment Tree Build.java	Medium	Java	[]
213	Segment Tree Modify.java	Medium	Java	[]
214	Segment Tree Query II.java	Medium	Java	[]
215	Segment Tree Query.java	Medium	Java	[]
216	Serilization and Deserialization Of Binary Tree.java	N/A	Java	[]
217	Shortest Word Distance.java	Easy	Java	[]
218	Single Number II.java	N/A	Java	[]
219	Single Number III.java	N/A	Java	[]
220	Single Number.java	Easy	Java	[]
221	Singleton.java	N/A	Java	[]
222	Sliding Window Maximum.java	N/A	Java	[]
223	Sliding Window Median.java	N/A	Java	[]
224	Sort Color.java	N/A	Java	[]
225	Sort Colors II.java	N/A	Java	[]
226	Sort Letters by Case.java	N/A	Java	[]
227	Sort List.java	N/A	Java	[]
228	Space Replacement.java	N/A	Java	[]
229	Sqrt(x).java	Easy	Java	[]
230	Stone Game.java	N/A	Java	[]
231	String Permutation.java	Easy	Java	[]
232	String to Integer(atoi).java	Easy	Java	[]
233	Strobogrammatic Number II.java	Medium	Java	[]
234	Strobogrammatic Number.java	Easy	Java	[]
235	StrStr.java	N/A	Java	[]
236	Subarray Sum Closest.java	Medium	Java	[]
237	Subarray Sum.java	Easy	Java	[]
238	Subset.java	Medium	Java	[]
239	Subsets II.java	Medium	Java	[]
240	Subtree.java	Easy	Java	[]
241	Summary Ranges.java	N/A	Java	[]
242	Surrounded Regions.java	N/A	Java	[]
243	Swap Nodes in Pairs.java	N/A	Java	[]
244	Symmetric Binary Tree.java	Easy	Java	[]
245	The Smallest Difference.java	N/A	Java	[]
246	Top K Frequent Elements.java	Medium	Java	[]
247	Top K Frequent Words.java	Medium	Java	[]
248	Topological Sorting.java	Medium	Java	[]
249	Total Occurrence of Target.java	N/A	Java	[]
250	Trailing Zeros.java	N/A	Java	[]
251	Trapping Rain Water II.java	Hard	Java	[]
252	Tweaked Identical Binary Tree.java	Easy	Java	[]
253	Two Lists Sum.java	N/A	Java	[]
254	Two Strings Are Anagrams.java	Easy	Java	[]
255	Ugly Number II.java	N/A	Java	[]
256	Ugly Number.java	Medium	Java	[]
257	Unique Binary Search Tree II.java	N/A	Java	[]
258	Unique Characters.java	N/A	Java	[]
259	Unique Word Abbreviation.java	N/A	Java	[]
260	Valid Palindrome.java	Easy	Java	[]
261	Valid Parentheses.java	Easy	Java	[]
262	Valid Sudoku.java	Easy	Java	[]
263	Wood Cut.java	N/A	Java	[]
264	Word Break.java	Medium	Java	[]
265	Word Ladder II.java	Hard	Java	[]
266	Word Ladder.java	Medium	Java	[]
267	Word Pattern.java	Easy	Java	[]
268	Word Search II.java	Hard	Java	[]
269	Word Search.java	Medium	Java	[]
270	Zigzag Iterator.java	N/A	Java	[]
271	Find Anagram Mappings.java	Easy	Java	[]
272	Judge Route Circle.java	Easy	Java	[]
273	Island Perimeter.java	Easy	Java	[]
274	First Unique Character in a String.java	Easy	Java	[]
275	Power of Three.java	Easy	Java	[]
276	Plus One.java	Easy	Java	[]
277	Power of Two.java	Easy	Java	[]
278	Reverse Vowels of a String.java	Easy	Java	[]
279	Guess Number Higher or Lower.java	Easy	Java	[]
280	Encode and Decode TinyURL.java	Medium	Java	[]
281	Wiggle Sort.java	Medium	Java	[]
282	Queue Reconstruction by Height.java	Medium	Java	[]
283	2 Sum.java	Easy	Java	[]	Link
284	2 Sum II - Input array is sorted.java	Medium	Java	[]
285	2 Sum II.java	Medium	Java	[]
286	Coin Change.java	Medium	Java	[]
287	Unique Path.java	Medium	Java	[]
288	Jump Game.java	Medium	Java	[]
289	Maximum Product Subarray.java	Medium	Java	[]
290	3 Sum Closest.java	Medium	Java	[]
291	Triangle Count.java	Medium	Java	[]
292	3 Sum.java	Medium	Java	[]
293	4 Sum.java	Medium	Java	[]
294	k Sum.java	Hard	Java	[]
295	Trapping Rain Water.java	Hard	Java	[]
296	Longest Continuous Increasing Subsequence.java	Easy	Java	[]
297	Longest Increasing Subsequence.java	Medium	Java	[]
298	Unique Binary Search Tree.java	Medium	Java	[]
299	Trim a Binary Search Tree.java	Easy	Java	[]
300	Unique Paths II.java	Medium	Java	[]
301	Counting Bits.java	Medium	Java	[]
302	Bomb Enemy.java	Medium	Java	[]
303	Paint House.java	Easy	Java	[]
304	Decode Ways.java	Review	Java	[]
305	House Robber.java	Easy	Java	[]
306	House Robber II.java	Medium	Java	[]
307	Best Time to Buy and Sell Stock I.java	Easy	Java	[]
308	Best Time to Buy and Sell Stock II.java	Easy	Java	[]
309	Best Time to Buy and Sell Stock III .java	Hard	Java	[]
310	Best Time to Buy and Sell Stock IV.java	Hard	Java	[]
311	Paint House II.java	Review	Java	[]
312	3 Sum Smaller.java	Medium	Java	[]
313	Array Partition I.java	Easy	Java	[]
314	1-bit and 2-bit Characters.java	Easy	Java	[]
315	Non-decreasing Array.java	Easy	Java	[]
316	Max Consecutive Ones.java	Easy	Java	[]
317	Find All Numbers Disappeared in an Array.java	Easy	Java	[]
318	Maximum Average Subarray I.java	Easy	Java	[]
319	Largest Number At Least Twice of Others.java	Easy	Java	[]
320	Toeplitz Matrix.java	Easy	Java	[]
321	Backpack.java	Medium	Java	[]
322	A+B.java	Easy	Java	[]
323	Swap Bits.java	Easy	Java	[]
324	Update Bits.java	Medium	Java	[]
325	Maximum XOR of Two Numbers in an Array.java	Medium	Java	[]
326	Coins in a Line.java	Medium	Java	[]
327	Perfect Squares.java	Medium	Java	[]
328	Palindrome Partitioning II.java	Hard	Java	[]
329	Backpack V.java	Medium	Java	[]
330	Backpack VI.java	Medium	Java	[]
331	Copy Books.java	Review	Java	[]
332	Valid Perfect Square.java	Review	Java	[]
333	Intersection of Two Arrays II.java	Easy	Java	[]
334	First Bad Version.java	Easy	Java	[]
335	Backpack II.java	Medium	Java	[]
336	Backpack III.java	Review	Java	[]
337	Longest Palindromic Subsequence.java	Medium	Java	[]
338	Burst Balloons.java	Hard	Java	[]
339	Scramble String.java	Hard	Java	[]
340	Binary Search Tree Iterator.java	Medium	Java	[]
341	Flatten Nested List Iterator.java	Medium	Java	[]
342	Coins in a Line III.java	Hard	Java	[]
343	Best Time to Buy and Sell Stock with Cooldown.java	Medium	Java	[]
344	Find Peak Element.java	Medium	Java	[Array, Binary Search]
345	Longest Common Subsequence.java	Medium	Java	[]
346	Interleaving String.java	Hard	Java	[]
347	Letter Combinations of a Phone Number.java	Medium	Java	[]
348	Edit Distance.java	Hard	Java	[]
349	Distinct Subsequences.java	Hard	Java	[]
350	Regular Expression Matching.java	Review	Java	[]
351	Majority Element.java	Easy	Java	[]
352	Wildcard Matching.java	Hard	Java	[]
353	Ones and Zeroes.java	Hard	Java	[]
354	Pow(x,n).java	Medium	Java	[]
355	Word Break II.java	Review	Java	[]
356	Nested List Weight Sum.java	Easy	Java	[]
357	Same Tree.java	Easy	Java	[]
358	Convert Sorted Array to Binary Search Tree.java	Easy	Java	[]
359	Binary Tree Maximum Path Sum.java	Review	Java	[]
360	Construct Binary Tree from Inorder and Preorder Traversal.java	Medium	Java	[]
361	Path Sum.java	Easy	Java	[]
362	Add and Search Word.java	Medium	Java	[]
363	Add Binary.java	Easy	Java	[]
364	Add Digits.java	Easy	Java	[]
365	Add Two Numbers.java	Medium	Java	[]
366	Add Two Numbers II.java	Medium	Java	[]
367	Balanced Binary Tree.java	Medium	Java	[]
368	Valid Anagram.java	Easy	Java	[]
369	Populating Next Right Pointers in Each Node.java	Medium	Java	[]
370	Validate Binary Search Tree.java	Medium	Java	[]
371	Convert Sorted List to Binary Search Tree.java	Medium	Java	[]
372	Flatten Binary Tree to Linked List.java	Medium	Java	[Binary Tree, DFS]
373	Binary Tree Paths.java	Easy	Java	[Binary Tree, DFS]
374	Minimum Size Subarray Sum.java	Medium	Java	[Array, Binary Search, Two Pointers]
375	Clone Graph.java	Medium	Java	[BFS, DFS, Graph]
376	Longest Substring Without Repeating Characters.java	Medium	Java	[Hash Table, String, Two Pointers]
377	Minimum Window Substring.java	Hard	Java	[Hash Table, String, Two Pointers]
378	Linked List Cycle.java	Easy	Java	[Linked List, Two Pointers]
379	Remove Nth Node From End of List.java	Medium	Java	[Linked List, Two Pointers]
380	Longest Substring with At Most K Distinct Characters.java	Medium	Java	[Hash Table, String]
381	Linked List Cycle II.java	Medium	Java	[Linked List, Two Pointers]
382	Kth Smallest Number in Sorted Matrix.java	Medium	Java	[Binary Search, Heap]
383	Find Minimum in Rotated Sorted Array.java	Medium	Java	[Array, Binary Search]
384	Find Minimum in Rotated Sorted Array II.java	Hard	Java	[Array, Binary Search]
385	Connecting Graph.java	Medium	Java	[Union Find]
386	Connecting Graph II.java	Medium	Java	[Union Find]
387	Connecting Graph III.java	Medium	Java	[Union Find]
388	Number of Islands.java	Medium	Java	[BFS, DFS, Union Find]
389	Number of Islands II.java	Hard	Java	[Union Find]
390	Graph Valid Tree.java	Medium	Java	[BFS, DFS, Graph, Union Find]