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

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Java Solutions to problems on LintCode/LeetCode

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