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:pencil2: LeetCode solutions in C++ 11 and Python3

Home Page: https://github.com/pezy/LeetCode#leetcode

License: MIT License

C++ 97.14% Python 2.86%

leetcode leetcode-solutions c-plus-plus-11 python3 notes

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LeetCode

LeetCode solutions in C++ 11 and Python3.

NO.	Title	Solution	Note	Difficulty	Tag
0	Two Sum	C++ Python	Note	Easy	`Mapping`
1	Add Two Numbers	C++ Python	Note	Medium	`LinkedList`
2	Longest Substring Without Repeating Characters	C++ Python	Note	Medium	`Mapping`
3	Median of Two Sorted Arrays	C++ Python	Note	Hard
4	Longest Palindromic Substring	C++ Python	Note	Medium
5	ZigZag Conversion	C++ Python	Note	Medium
6	Reverse Integer	C++ Python	Note	Easy
7	String to Integer (atoi)	C++ Python	Note	Medium
8	Palindrome Number	C++ Python	Note	Easy
9	Regular Expression Matching	C++ Python	Note	Hard
10	Container With Most Water	C++ Python	Note	Medium
11	Integer to Roman	C++ Python	Note	Medium
12	Roman to Integer	C++ Python	Note	Easy
13	Longest Common Prefix	C++ Python	Note	Easy
14	3Sum	C++ Python	Note	Medium
15	3Sum Closest	C++ Python	Note	Medium
16	Letter Combinations of a Phone Number	C++ Python	Note	Medium
17	4Sum	C++ Python	Note	Medium
18	Remove Nth Node From End of List	C++ Python	Note	Medium
19	Valid Parentheses	C++ Python	Note	Easy
20	Merge Two Sorted Lists	C++ Python	Note	Easy
21	Generate Parentheses	C++ Python	Note	Medium
22	Merge k Sorted Lists	C++ Python	Note	Hard
23	Swap Nodes in Pairs	C++ Python	Note	Medium
24	Reverse Nodes in k-Group	C++ Python	Note	Hard
25	Remove Duplicates from Sorted Array	C++ Python	Note	Easy
26	Remove Element	C++ Python	Note	Easy
27	Implement strStr()	C++ Python	Note	Easy
28	Divide Two Integers	C++ Python	Note	Medium
29	Substring with Concatenation of All Words	C++ Python	Note	Hard
30	Next Permutation	C++ Python	Note	Medium
31	Longest Valid Parentheses	C++ Python	Note	Hard
32	Search in Rotated Sorted Array	C++ Python	Note	Medium
33	Search for a Range	C++ Python	Note	Medium
34	Search Insert Position	C++ Python	Note	Easy
35	Valid Sudoku	C++ Python	Note	Medium
36	Sudoku Solver	C++ Python	Note	Hard
37	Count and Say	C++ Python	Note	Easy
38	Combination Sum	C++ Python	Note	Medium
39	Combination Sum II	C++ Python	Note	Medium
40	First Missing Positive	C++ Python	Note	Hard
41	Trapping Rain Water	C++ Python	Note	Hard
42	Multiply Strings	C++ Python	Note	Medium
43	Wildcard Matching	C++ Python	Note	Hard
44	Jump Game II	C++ Python	Note	Hard
45	Permutations	C++ Python	Note	Medium
46	Permutations II	C++ Python	Note	Medium
47	Rotate Image	C++ Python	Note	Medium
48	Group Anagrams	C++ Python	Note	Medium
49	Pow(x, n)	C++ Python	Note	Medium
50	N-Queens	C++ Python	Note	Hard
51	N-Queens II	C++ Python	Note	Hard
52	Maximum Subarray	C++ Python	Note	Easy
53	Spiral Matrix	C++ Python	Note	Medium
54	Jump Game	C++ Python	Note	Medium
55	Merge Intervals	C++ Python	Note	Medium
56	Insert Interval	C++ Python	Note	Hard
57	Length of Last Word	C++ Python	Note	Easy
58	Spiral Matrix II	C++ Python	Note	Medium
59	Permutation Sequence	C++ Python	Note	Medium
60	Rotate List	C++ Python	Note	Medium
61	Unique Paths	C++ Python	Note	Medium
62	Unique Paths II	C++ Python	Note	Medium
63	Minimum Path Sum	C++ Python	Note	Medium
64	Valid Number	C++ Python	Note	Hard
65	Plus One	C++ Python	Note	Easy
66	Add Binary	C++ Python	Note	Easy
67	Text Justification	C++ Python	Note	Hard
68	Sqrt(x)	C++ Python	Note	Easy
69	Climbing Stairs	C++ Python	Note	Easy
70	Simplify Path	C++ Python	Note	Medium
71	Edit Distance	C++ Python	Note	Hard
72	Set Matrix Zeroes	C++ Python	Note	Medium
73	Search a 2D Matrix	C++ Python	Note	Medium
74	Sort Colors	C++ Python	Note	Medium
75	Minimum Window Substring	C++ Python	Note	Hard
76	Combinations	C++ Python	Note	Medium
77	Subsets	C++ Python	Note	Medium
78	Word Search	C++ Python	Note	Medium
79	Remove Duplicates from Sorted Array II	C++ Python	Note	Medium
80	Search in Rotated Sorted Array II	C++ Python	Note	Medium
81	Remove Duplicates from Sorted List II	C++ Python	Note	Medium
82	Remove Duplicates from Sorted List	C++ Python	Note	Easy
83	Largest Rectangle in Histogram	C++ Python	Note	Hard
84	Maximal Rectangle	C++ Python	Note	Hard
85	Partition List	C++ Python	Note	Medium
86	Scramble String	C++ Python	Note	Hard
87	Merge Sorted Array	C++ Python	Note	Easy
88	Gray Code	C++ Python	Note	Medium
89	Subsets II	C++ Python	Note	Medium
90	Decode Ways	C++ Python	Note	Medium
91	Reverse Linked List II	C++ Python	Note	Medium
92	Restore IP Addresses	C++ Python	Note	Medium
93	Binary Tree Inorder Traversal	C++ Python	Note	Medium
94	Unique Binary Search Trees II	C++ Python	Note	Medium
95	Unique Binary Search Trees	C++ Python	Note	Medium
96	Interleaving String	C++ Python	Note	Hard
97	Validate Binary Search Tree	C++ Python	Note	Medium
98	Recover Binary Search Tree	C++ Python	Note	Hard
99	Same Tree	C++ Python	Note	Easy
100	Symmetric Tree	C++ Python	Note	Easy
101	Binary Tree Level Order Traversal	C++ Python	Note	Medium
102	Binary Tree Zigzag Level Order Traversal	C++ Python	Note	Medium
103	Maximum Depth of Binary Tree	C++ Python	Note	Easy
104	Construct Binary Tree from Preorder and Inorder Traversal	C++ Python	Note	Medium
105	Construct Binary Tree from Inorder and Postorder Traversal	C++ Python	Note	Medium
106	Binary Tree Level Order Traversal II	C++ Python	Note	Easy
107	Convert Sorted Array to Binary Search Tree	C++ Python	Note	Easy
108	Convert Sorted List to Binary Search Tree	C++ Python	Note	Medium
109	Balanced Binary Tree	C++ Python	Note	Easy
110	Minimum Depth of Binary Tree	C++ Python	Note	Easy
111	Path Sum	C++ Python	Note	Easy
112	Path Sum II	C++ Python	Note	Medium
113	Flatten Binary Tree to Linked List	C++ Python	Note	Medium
114	Distinct Subsequences	C++ Python	Note	Hard
115	Populating Next Right Pointers in Each Node	C++ Python	Note	Medium
116	Populating Next Right Pointers in Each Node II	C++ Python	Note	Medium
117	Pascal's Triangle	C++ Python	Note	Easy
118	Pascal's Triangle II	C++ Python	Note	Easy
119	Triangle	C++ Python	Note	Medium
120	Best Time to Buy and Sell Stock	C++ Python	Note	Easy
121	Best Time to Buy and Sell Stock II	C++ Python	Note	Easy
122	Best Time to Buy and Sell Stock III	C++ Python	Note	Hard
123	Binary Tree Maximum Path Sum	C++ Python	Note	Hard
124	Valid Palindrome	C++ Python	Note	Easy
125	Word Ladder II	C++ Python	Note	Hard
126	Word Ladder	C++ Python	Note	Medium
127	Longest Consecutive Sequence	C++ Python	Note	Hard
128	Sum Root to Leaf Numbers	C++ Python	Note	Medium
129	Surrounded Regions	C++ Python	Note	Medium
130	Palindrome Partitioning	C++ Python	Note	Medium
131	Palindrome Partitioning II	C++ Python	Note	Hard
132	Clone Graph	C++ Python	Note	Medium
133	Gas Station	C++ Python	Note	Medium
134	Candy	C++ Python	Note	Hard
135	Single Number	C++ Python	Note	Easy
136	Single Number II	C++ Python	Note	Medium
137	Copy List with Random Pointer	C++ Python	Note	Medium
138	Word Break	C++ Python	Note	Medium
139	Word Break II	C++ Python	Note	Hard
140	Linked List Cycle	C++ Python	Note	Easy
141	Linked List Cycle II	C++ Python	Note	Medium
142	Reorder List	C++ Python	Note	Medium
143	Binary Tree Preorder Traversal	C++ Python	Note	Medium
144	Binary Tree Postorder Traversal	C++ Python	Note	Hard
145	LRU Cache	C++ Python	Note	Hard
146	Insertion Sort List	C++ Python	Note	Medium
147	Sort List	C++ Python	Note	Medium
148	Max Points on a Line	C++ Python	Note	Hard
149	Evaluate Reverse Polish Notation	C++ Python	Note	Medium
150	Reverse Words in a String	C++ Python	Note	Medium
151	Maximum Product Subarray	C++ Python	Note	Medium
152	Find Minimum in Rotated Sorted Array	C++ Python	Note	Medium
153	Find Minimum in Rotated Sorted Array II	C++ Python	Note	Hard
154	Min Stack	C++ Python	Note	Easy
155	Binary Tree Upside Down	C++ Python	Note	None
156	Read N Characters Given Read4	C++ Python	Note	None
157	Read N Characters Given Read4 II - Call multiple times	C++ Python	Note	None
158	Longest Substring with At Most Two Distinct Characters	C++ Python	Note	None
159	Intersection of Two Linked Lists	C++ Python	Note	Easy
160	One Edit Distance	C++ Python	Note	None
161	Find Peak Element	C++ Python	Note	Medium
162	Missing Ranges	C++ Python	Note	None
163	Maximum Gap	C++ Python	Note	Hard
164	Compare Version Numbers	C++ Python	Note	Medium
165	Fraction to Recurring Decimal	C++ Python	Note	Medium
166	Two Sum II - Input array is sorted	C++ Python	Note	Easy
167	Excel Sheet Column Title	C++ Python	Note	Easy
168	Majority Element	C++ Python	Note	Easy
169	Two Sum III - Data structure design	C++ Python	Note	None
170	Excel Sheet Column Number	C++ Python	Note	Easy
171	Factorial Trailing Zeroes	C++ Python	Note	Easy
172	Binary Search Tree Iterator	C++ Python	Note	Medium
173	Dungeon Game	C++ Python	Note	Hard
174	Combine Two Tables	C++ Python	Note	Easy
175	Second Highest Salary	C++ Python	Note	Easy
176	Nth Highest Salary	C++ Python	Note	Medium
177	Rank Scores	C++ Python	Note	Medium
178	Largest Number	C++ Python	Note	Medium
179	Consecutive Numbers	C++ Python	Note	Medium
180	Employees Earning More Than Their Managers	C++ Python	Note	Easy
181	Duplicate Emails	C++ Python	Note	Easy
182	Customers Who Never Order	C++ Python	Note	Easy
183	Department Highest Salary	C++ Python	Note	Medium
184	Department Top Three Salaries	C++ Python	Note	Hard
185	Reverse Words in a String II	C++ Python	Note	None
186	Repeated DNA Sequences	C++ Python	Note	Medium
187	Best Time to Buy and Sell Stock IV	C++ Python	Note	Hard
188	Rotate Array	C++ Python	Note	Easy
189	Reverse Bits	C++ Python	Note	Easy
190	Number of 1 Bits	C++ Python	Note	Easy
191	Word Frequency	C++ Python	Note	Medium
192	Valid Phone Numbers	C++ Python	Note	Easy
193	Transpose File	C++ Python	Note	Medium
194	Tenth Line	C++ Python	Note	Easy
195	Delete Duplicate Emails	C++ Python	Note	Easy
196	Rising Temperature	C++ Python	Note	Easy
197	House Robber	C++ Python	Note	Easy
198	Binary Tree Right Side View	C++ Python	Note	Medium
199	Number of Islands	C++ Python	Note	Medium
200	Bitwise AND of Numbers Range	C++ Python	Note	Medium
201	Happy Number	C++ Python	Note	Easy
202	Remove Linked List Elements	C++ Python	Note	Easy
203	Count Primes	C++ Python	Note	Easy
204	Isomorphic Strings	C++ Python	Note	Easy
205	Reverse Linked List	C++ Python	Note	Easy
206	Course Schedule	C++ Python	Note	Medium
207	Implement Trie (Prefix Tree)	C++ Python	Note	Medium
208	Minimum Size Subarray Sum	C++ Python	Note	Medium
209	Course Schedule II	C++ Python	Note	Medium
210	Add and Search Word - Data structure design	C++ Python	Note	Medium
211	Word Search II	C++ Python	Note	Hard
212	House Robber II	C++ Python	Note	Medium
213	Shortest Palindrome	C++ Python	Note	Hard
214	Kth Largest Element in an Array	C++ Python	Note	Medium
215	Combination Sum III	C++ Python	Note	Medium
216	Contains Duplicate	C++ Python	Note	Easy
217	The Skyline Problem	C++ Python	Note	Hard
218	Contains Duplicate II	C++ Python	Note	Easy
219	Contains Duplicate III	C++ Python	Note	Medium
220	Maximal Square	C++ Python	Note	Medium
221	Count Complete Tree Nodes	C++ Python	Note	Medium
222	Rectangle Area	C++ Python	Note	Medium
223	Basic Calculator	C++ Python	Note	Hard
224	Implement Stack using Queues	C++ Python	Note	Easy
225	Invert Binary Tree	C++ Python	Note	Easy
226	Basic Calculator II	C++ Python	Note	Medium
227	Summary Ranges	C++ Python	Note	Medium
228	Majority Element II	C++ Python	Note	Medium
229	Kth Smallest Element in a BST	C++ Python	Note	Medium
230	Power of Two	C++ Python	Note	Easy
231	Implement Queue using Stacks	C++ Python	Note	Easy
232	Number of Digit One	C++ Python	Note	Hard
233	Palindrome Linked List	C++ Python	Note	Easy
234	Lowest Common Ancestor of a Binary Search Tree	C++ Python	Note	Easy
235	Lowest Common Ancestor of a Binary Tree	C++ Python	Note	Medium
236	Delete Node in a Linked List	C++ Python	Note	Easy
237	Product of Array Except Self	C++ Python	Note	Medium
238	Sliding Window Maximum	C++ Python	Note	Hard
239	Search a 2D Matrix II	C++ Python	Note	Medium
240	Different Ways to Add Parentheses	C++ Python	Note	Medium
241	Valid Anagram	C++ Python	Note	Easy
242	Shortest Word Distance	C++ Python	Note	None
243	Shortest Word Distance II	C++ Python	Note	None
244	Shortest Word Distance III	C++ Python	Note	None
245	Strobogrammatic Number	C++ Python	Note	None
246	Strobogrammatic Number II	C++ Python	Note	None
247	Strobogrammatic Number III	C++ Python	Note	None
248	Group Shifted Strings	C++ Python	Note	None
249	Count Univalue Subtrees	C++ Python	Note	None
250	Flatten 2D Vector	C++ Python	Note	None
251	Meeting Rooms	C++ Python	Note	None
252	Meeting Rooms II	C++ Python	Note	None
253	Factor Combinations	C++ Python	Note	None
254	Verify Preorder Sequence in Binary Search Tree	C++ Python	Note	None
255	Paint House	C++ Python	Note	None
256	Binary Tree Paths	C++ Python	Note	Easy
257	Add Digits	C++ Python	Note	Easy
258	3Sum Smaller	C++ Python	Note	None
259	Single Number III	C++ Python	Note	Medium
260	Graph Valid Tree	C++ Python	Note	None
261	Trips and Users	C++ Python	Note	Hard
262	Ugly Number	C++ Python	Note	Easy
263	Ugly Number II	C++ Python	Note	Medium
264	Paint House II	C++ Python	Note	None
265	Palindrome Permutation	C++ Python	Note	None
266	Palindrome Permutation II	C++ Python	Note	None
267	Missing Number	C++ Python	Note	Easy
268	Alien Dictionary	C++ Python	Note	None
269	Closest Binary Search Tree Value	C++ Python	Note	None
270	Encode and Decode Strings	C++ Python	Note	None
271	Closest Binary Search Tree Value II	C++ Python	Note	None
272	Integer to English Words	C++ Python	Note	Hard
273	H-Index	C++ Python	Note	Medium
274	H-Index II	C++ Python	Note	Medium
275	Paint Fence	C++ Python	Note	None
276	Find the Celebrity	C++ Python	Note	None
277	First Bad Version	C++ Python	Note	Easy
278	Perfect Squares	C++ Python	Note	Medium
279	Wiggle Sort	C++ Python	Note	None
280	Zigzag Iterator	C++ Python	Note	None
281	Expression Add Operators	C++ Python	Note	Hard
282	Move Zeroes	C++ Python	Note	Easy
283	Peeking Iterator	C++ Python	Note	Medium
284	Inorder Successor in BST	C++ Python	Note	None
285	Walls and Gates	C++ Python	Note	None
286	Find the Duplicate Number	C++ Python	Note	Medium
287	Unique Word Abbreviation	C++ Python	Note	None
288	Game of Life	C++ Python	Note	Medium
289	Word Pattern	C++ Python	Note	Easy
290	Word Pattern II	C++ Python	Note	None
291	Nim Game	C++ Python	Note	Easy
292	Flip Game	C++ Python	Note	None
293	Flip Game II	C++ Python	Note	None
294	Find Median from Data Stream	C++ Python	Note	Hard
295	Best Meeting Point	C++ Python	Note	None
296	Serialize and Deserialize Binary Tree	C++ Python	Note	Hard
297	Binary Tree Longest Consecutive Sequence	C++ Python	Note	None
298	Bulls and Cows	C++ Python	Note	Medium
299	Longest Increasing Subsequence	C++ Python	Note	Medium
300	Remove Invalid Parentheses	C++ Python	Note	Hard
301	Smallest Rectangle Enclosing Black Pixels	C++ Python	Note	None
302	Range Sum Query - Immutable	C++ Python	Note	Easy
303	Range Sum Query 2D - Immutable	C++ Python	Note	Medium
304	Number of Islands II	C++ Python	Note	None
305	Additive Number	C++ Python	Note	Medium
306	Range Sum Query - Mutable	C++ Python	Note	Medium
307	Range Sum Query 2D - Mutable	C++ Python	Note	None
308	Best Time to Buy and Sell Stock with Cooldown	C++ Python	Note	Medium
309	Minimum Height Trees	C++ Python	Note	Medium
310	Sparse Matrix Multiplication	C++ Python	Note	None
311	Burst Balloons	C++ Python	Note	Hard
312	Super Ugly Number	C++ Python	Note	Medium
313	Binary Tree Vertical Order Traversal	C++ Python	Note	None
314	Count of Smaller Numbers After Self	C++ Python	Note	Hard
315	Remove Duplicate Letters	C++ Python	Note	Hard
316	Shortest Distance from All Buildings	C++ Python	Note	None
317	Maximum Product of Word Lengths	C++ Python	Note	Medium
318	Bulb Switcher	C++ Python	Note	Medium
319	Generalized Abbreviation	C++ Python	Note	None
320	Create Maximum Number	C++ Python	Note	Hard
321	Coin Change	C++ Python	Note	Medium
322	Number of Connected Components in an Undirected Graph	C++ Python	Note	None
323	Wiggle Sort II	C++ Python	Note	Medium
324	Maximum Size Subarray Sum Equals k	C++ Python	Note	None
325	Power of Three	C++ Python	Note	Easy
326	Count of Range Sum	C++ Python	Note	Hard
327	Odd Even Linked List	C++ Python	Note	Medium
328	Longest Increasing Path in a Matrix	C++ Python	Note	Hard
329	Patching Array	C++ Python	Note	Hard
330	Verify Preorder Serialization of a Binary Tree	C++ Python	Note	Medium
331	Reconstruct Itinerary	C++ Python	Note	Medium
332	Largest BST Subtree	C++ Python	Note	None
333	Increasing Triplet Subsequence	C++ Python	Note	Medium
334	Self Crossing	C++ Python	Note	Hard
335	Palindrome Pairs	C++ Python	Note	Hard
336	House Robber III	C++ Python	Note	Medium
337	Counting Bits	C++ Python	Note	Medium
338	Nested List Weight Sum	C++ Python	Note	None
339	Longest Substring with At Most K Distinct Characters	C++ Python	Note	None
340	Flatten Nested List Iterator	C++ Python	Note	Medium
341	Power of Four	C++ Python	Note	Easy
342	Integer Break	C++ Python	Note	Medium
343	Reverse String	C++ Python	Note	Easy
344	Reverse Vowels of a String	C++ Python	Note	Easy
345	Moving Average from Data Stream	C++ Python	Note	None
346	Top K Frequent Elements	C++ Python	Note	Medium
347	Design Tic-Tac-Toe	C++ Python	Note	None
348	Intersection of Two Arrays	C++ Python	Note	Easy
349	Intersection of Two Arrays II	C++ Python	Note	Easy
350	Android Unlock Patterns	C++ Python	Note	None
351	Data Stream as Disjoint Intervals	C++ Python	Note	Hard
352	Design Snake Game	C++ Python	Note	None
353	Russian Doll Envelopes	C++ Python	Note	Hard
354	Design Twitter	C++ Python	Note	Medium
355	Line Reflection	C++ Python	Note	None
356	Count Numbers with Unique Digits	C++ Python	Note	Medium
357	Rearrange String k Distance Apart	C++ Python	Note	None
358	Logger Rate Limiter	C++ Python	Note	None
359	Sort Transformed Array	C++ Python	Note	None
360	Bomb Enemy	C++ Python	Note	None
361	Design Hit Counter	C++ Python	Note	None
362	Max Sum of Rectangle No Larger Than K	C++ Python	Note	Hard
363	Nested List Weight Sum II	C++ Python	Note	None
364	Water and Jug Problem	C++ Python	Note	Medium
365	Find Leaves of Binary Tree	C++ Python	Note	None
366	Valid Perfect Square	C++ Python	Note	Easy
367	Largest Divisible Subset	C++ Python	Note	Medium
368	Plus One Linked List	C++ Python	Note	None
369	Range Addition	C++ Python	Note	None
370	Sum of Two Integers	C++ Python	Note	Easy
371	Super Pow	C++ Python	Note	Medium
372	Find K Pairs with Smallest Sums	C++ Python	Note	Medium
373	Guess Number Higher or Lower	C++ Python	Note	Easy
374	Guess Number Higher or Lower II	C++ Python	Note	Medium
375	Wiggle Subsequence	C++ Python	Note	Medium
376	Combination Sum IV	C++ Python	Note	Medium
377	Kth Smallest Element in a Sorted Matrix	C++ Python	Note	Medium
378	Design Phone Directory	C++ Python	Note	None
379	Insert Delete GetRandom O(1)	C++ Python	Note	Medium
380	Insert Delete GetRandom O(1) - Duplicates allowed	C++ Python	Note	Hard
381	Linked List Random Node	C++ Python	Note	Medium
382	Ransom Note	C++ Python	Note	Easy
383	Shuffle an Array	C++ Python	Note	Medium
384	Mini Parser	C++ Python	Note	Medium
385	Lexicographical Numbers	C++ Python	Note	Medium
386	First Unique Character in a String	C++ Python	Note	Easy
387	Longest Absolute File Path	C++ Python	Note	Medium
388	Find the Difference	C++ Python	Note	Easy
389	Elimination Game	C++ Python	Note	Medium
390	Perfect Rectangle	C++ Python	Note	Hard
391	Is Subsequence	C++ Python	Note	Medium
392	UTF-8 Validation	C++ Python	Note	Medium
393	Decode String	C++ Python	Note	Medium
394	Longest Substring with At Least K Repeating Characters	C++ Python	Note	Medium
395	Rotate Function	C++ Python	Note	Medium
396	Integer Replacement	C++ Python	Note	Medium
397	Random Pick Index	C++ Python	Note	Medium
398	Evaluate Division	C++ Python	Note	Medium
399	Nth Digit	C++ Python	Note	Easy
400	Binary Watch	C++ Python	Note	Easy
401	Remove K Digits	C++ Python	Note	Medium
402	Frog Jump	C++ Python	Note	Hard
403	Sum of Left Leaves	C++ Python	Note	Easy
404	Convert a Number to Hexadecimal	C++ Python	Note	Easy
405	Queue Reconstruction by Height	C++ Python	Note	Medium
406	Trapping Rain Water II	C++ Python	Note	Hard
407	Valid Word Abbreviation	C++ Python	Note	None
408	Longest Palindrome	C++ Python	Note	Easy
409	Split Array Largest Sum	C++ Python	Note	Hard
410	Minimum Unique Word Abbreviation	C++ Python	Note	None
411	Fizz Buzz	C++ Python	Note	Easy
412	Arithmetic Slices	C++ Python	Note	Medium
413	Third Maximum Number	C++ Python	Note	Easy
414	Add Strings	C++ Python	Note	Easy
415	Partition Equal Subset Sum	C++ Python	Note	Medium
416	Pacific Atlantic Water Flow	C++ Python	Note	Medium
417	Sentence Screen Fitting	C++ Python	Note	None
418	Battleships in a Board	C++ Python	Note	Medium
419	Strong Password Checker	C++ Python	Note	Hard
420	Maximum XOR of Two Numbers in an Array	C++ Python	Note	Medium
421	Valid Word Square	C++ Python	Note	None
422	Reconstruct Original Digits from English	C++ Python	Note	Medium
423	Longest Repeating Character Replacement	C++ Python	Note	Medium
424	Word Squares	C++ Python	Note	None
425	All O'one Data Structure	C++ Python	Note	Hard
426	Minimum Genetic Mutation	C++ Python	Note	Medium
427	Number of Segments in a String	C++ Python	Note	Easy
428	Non-overlapping Intervals	C++ Python	Note	Medium
429	Find Right Interval	C++ Python	Note	Medium
430	Path Sum III	C++ Python	Note	Easy
431	Find All Anagrams in a String	C++ Python	Note	Easy
432	Ternary Expression Parser	C++ Python	Note	None
433	K-th Smallest in Lexicographical Order	C++ Python	Note	Hard
434	Arranging Coins	C++ Python	Note	Easy
435	Find All Duplicates in an Array	C++ Python	Note	Medium
436	String Compression	C++ Python	Note	Easy
437	Sequence Reconstruction	C++ Python	Note	None
438	Add Two Numbers II	C++ Python	Note	Medium
439	Arithmetic Slices II - Subsequence	C++ Python	Note	Hard
440	Number of Boomerangs	C++ Python	Note	Easy
441	Find All Numbers Disappeared in an Array	C++ Python	Note	Easy
442	Serialize and Deserialize BST	C++ Python	Note	Medium
443	Delete Node in a BST	C++ Python	Note	Medium
444	Sort Characters By Frequency	C++ Python	Note	Medium
445	Minimum Number of Arrows to Burst Balloons	C++ Python	Note	Medium
446	Minimum Moves to Equal Array Elements	C++ Python	Note	Easy
447	4Sum II	C++ Python	Note	Medium
448	Assign Cookies	C++ Python	Note	Easy
449	132 Pattern	C++ Python	Note	Medium
450	Circular Array Loop	C++ Python	Note	Medium
451	Poor Pigs	C++ Python	Note	Easy
452	Repeated Substring Pattern	C++ Python	Note	Easy
453	LFU Cache	C++ Python	Note	Hard
454	Hamming Distance	C++ Python	Note	Easy
455	Minimum Moves to Equal Array Elements II	C++ Python	Note	Medium
456	Island Perimeter	C++ Python	Note	Easy
457	Can I Win	C++ Python	Note	Medium
458	Optimal Account Balancing	C++ Python	Note	None
459	Count The Repetitions	C++ Python	Note	Hard
460	Unique Substrings in Wraparound String	C++ Python	Note	Medium
461	Validate IP Address	C++ Python	Note	Medium
462	Convex Polygon	C++ Python	Note	None
463	Encode String with Shortest Length	C++ Python	Note	None
464	Concatenated Words	C++ Python	Note	Hard
465	Matchsticks to Square	C++ Python	Note	Medium
466	Ones and Zeroes	C++ Python	Note	Medium
467	Heaters	C++ Python	Note	Easy
468	Number Complement	C++ Python	Note	Easy
469	Total Hamming Distance	C++ Python	Note	Medium
470	Largest Palindrome Product	C++ Python	Note	Easy
471	Sliding Window Median	C++ Python	Note	Hard
472	Magical String	C++ Python	Note	Medium
473	License Key Formatting	C++ Python	Note	Easy
474	Smallest Good Base	C++ Python	Note	Hard
475	Find Permutation	C++ Python	Note	None
476	Max Consecutive Ones	C++ Python	Note	Easy
477	Predict the Winner	C++ Python	Note	Medium
478	Max Consecutive Ones II	C++ Python	Note	None
479	Zuma Game	C++ Python	Note	Hard
480	The Maze	C++ Python	Note	None
481	Increasing Subsequences	C++ Python	Note	Medium
482	Construct the Rectangle	C++ Python	Note	Easy
483	Reverse Pairs	C++ Python	Note	Hard
484	Target Sum	C++ Python	Note	Medium
485	Teemo Attacking	C++ Python	Note	Medium
486	Next Greater Element I	C++ Python	Note	Easy
487	Diagonal Traverse	C++ Python	Note	Medium
488	The Maze III	C++ Python	Note	None
489	Keyboard Row	C++ Python	Note	Easy
490	Find Mode in Binary Search Tree	C++ Python	Note	Easy
491	IPO	C++ Python	Note	Hard
492	Next Greater Element II	C++ Python	Note	Medium
493	Base 7	C++ Python	Note	Easy
494	The Maze II	C++ Python	Note	None
495	Relative Ranks	C++ Python	Note	Easy
496	Perfect Number	C++ Python	Note	Easy
497	Most Frequent Subtree Sum	C++ Python	Note	Medium
498	Find Bottom Left Tree Value	C++ Python	Note	Medium
499	Freedom Trail	C++ Python	Note	Hard
500	Find Largest Value in Each Tree Row	C++ Python	Note	Medium
501	Longest Palindromic Subsequence	C++ Python	Note	Medium
502	Super Washing Machines	C++ Python	Note	Hard
503	Coin Change 2	C++ Python	Note	Medium
504	Detect Capital	C++ Python	Note	Easy
505	Longest Uncommon Subsequence I	C++ Python	Note	Easy
506	Longest Uncommon Subsequence II	C++ Python	Note	Medium
507	Continuous Subarray Sum	C++ Python	Note	Medium
508	Longest Word in Dictionary through Deleting	C++ Python	Note	Medium
509	Contiguous Array	C++ Python	Note	Medium
510	Beautiful Arrangement	C++ Python	Note	Medium
511	Word Abbreviation	C++ Python	Note	None
512	Minesweeper	C++ Python	Note	Medium
513	Minimum Absolute Difference in BST	C++ Python	Note	Easy
514	Lonely Pixel I	C++ Python	Note	None
515	K-diff Pairs in an Array	C++ Python	Note	Easy
516	Lonely Pixel II	C++ Python	Note	None
517	Design TinyURL	C++ Python	Note	Medium
518	Encode and Decode TinyURL	C++ Python	Note	Medium
519	Construct Binary Tree from String	C++ Python	Note	None
520	Complex Number Multiplication	C++ Python	Note	Medium
521	Convert BST to Greater Tree	C++ Python	Note	Easy
522	Minimum Time Difference	C++ Python	Note	Medium
523	Single Element in a Sorted Array	C++ Python	Note	Medium
524	Reverse String II	C++ Python	Note	Easy
525	01 Matrix	C++ Python	Note	Medium
526	Diameter of Binary Tree	C++ Python	Note	Easy
527	Output Contest Matches	C++ Python	Note	None
528	Boundary of Binary Tree	C++ Python	Note	None
529	Remove Boxes	C++ Python	Note	Hard
530	Friend Circles	C++ Python	Note	Medium
531	Split Array with Equal Sum	C++ Python	Note	None
532	Binary Tree Longest Consecutive Sequence II	C++ Python	Note	None
533	Student Attendance Record I	C++ Python	Note	Easy
534	Student Attendance Record II	C++ Python	Note	Hard
535	Optimal Division	C++ Python	Note	Medium
536	Brick Wall	C++ Python	Note	Medium
537	Split Concatenated Strings	C++ Python	Note	None
538	Next Greater Element III	C++ Python	Note	Medium
539	Reverse Words in a String III	C++ Python	Note	Easy
540	Subarray Sum Equals K	C++ Python	Note	Medium
541	Array Partition I	C++ Python	Note	Easy
542	Longest Line of Consecutive One in Matrix	C++ Python	Note	None
543	Binary Tree Tilt	C++ Python	Note	Easy
544	Find the Closest Palindrome	C++ Python	Note	Hard
545	Array Nesting	C++ Python	Note	Medium
546	Reshape the Matrix	C++ Python	Note	Easy
547	Permutation in String	C++ Python	Note	Medium
548	Maximum Vacation Days	C++ Python	Note	None
549	Median Employee Salary	C++ Python	Note	None
550	Managers with at Least 5 Direct Reports	C++ Python	Note	None
551	Find Median Given Frequency of Numbers	C++ Python	Note	None
552	Subtree of Another Tree	C++ Python	Note	Easy
553	Squirrel Simulation	C++ Python	Note	None
554	Winning Candidate	C++ Python	Note	None
555	Distribute Candies	C++ Python	Note	Easy
556	Out of Boundary Paths	C++ Python	Note	Medium
557	Employee Bonus	C++ Python	Note	None
558	Get Highest Answer Rate Question	C++ Python	Note	None
559	Find Cumulative Salary of an Employee	C++ Python	Note	None
560	Count Student Number in Departments	C++ Python	Note	None
561	Shortest Unsorted Continuous Subarray	C++ Python	Note	Easy
562	Kill Process	C++ Python	Note	None
563	Delete Operation for Two Strings	C++ Python	Note	Medium
564	Find Customer Referee	C++ Python	Note	None
565	Investments in 2016	C++ Python	Note	None
566	Customer Placing the Largest Number of Orders	C++ Python	Note	None
567	Erect the Fence	C++ Python	Note	Hard
568	Design In-Memory File System	C++ Python	Note	None
569	Tag Validator	C++ Python	Note	Hard
570	Fraction Addition and Subtraction	C++ Python	Note	Medium
571	Valid Square	C++ Python	Note	Medium
572	Longest Harmonious Subsequence	C++ Python	Note	Easy
573	Big Countries	C++ Python	Note	Easy
574	Classes More Than 5 Students	C++ Python	Note	Easy
575	Friend Requests I: Overall Acceptance Rate	C++ Python	Note	None
576	Range Addition II	C++ Python	Note	Easy
577	Minimum Index Sum of Two Lists	C++ Python	Note	Easy
578	Non-negative Integers without Consecutive Ones	C++ Python	Note	Hard
579	Human Traffic of Stadium	C++ Python	Note	Hard
580	Friend Requests II: Who Has the Most Friends	C++ Python	Note	None
581	Consecutive Available Seats	C++ Python	Note	None
582	Design Compressed String Iterator	C++ Python	Note	None
583	Can Place Flowers	C++ Python	Note	Easy
584	Construct String from Binary Tree	C++ Python	Note	Easy
585	Sales Person	C++ Python	Note	None
586	Tree Node	C++ Python	Note	None
587	Find Duplicate File in System	C++ Python	Note	Medium
588	Triangle Judgement	C++ Python	Note	None
589	Valid Triangle Number	C++ Python	Note	Medium
590	Shortest Distance in a Plane	C++ Python	Note	None
591	Shortest Distance in a Line	C++ Python	Note	None
592	Second Degree Follower	C++ Python	Note	None
593	Average Salary: Departments VS Company	C++ Python	Note	None
594	Add Bold Tag in String	C++ Python	Note	None
595	Merge Two Binary Trees	C++ Python	Note	Easy
596	Students Report By Geography	C++ Python	Note	None
597	Biggest Single Number	C++ Python	Note	None
598	Not Boring Movies	C++ Python	Note	Easy
599	Task Scheduler	C++ Python	Note	Medium
600	Add One Row to Tree	C++ Python	Note	Medium
601	Maximum Distance in Arrays	C++ Python	Note	None
602	Minimum Factorization	C++ Python	Note	None
603	Exchange Seats	C++ Python	Note	Medium
604	Swap Salary	C++ Python	Note	Easy
605	Maximum Product of Three Numbers	C++ Python	Note	Easy
606	K Inverse Pairs Array	C++ Python	Note	Hard
607	Course Schedule III	C++ Python	Note	Hard
608	Design Excel Sum Formula	C++ Python	Note	None
609	Smallest Range	C++ Python	Note	Hard
610	Sum of Square Numbers	C++ Python	Note	Easy
611	Find the Derangement of An Array	C++ Python	Note	None
612	Design Log Storage System	C++ Python	Note	None
613	Exclusive Time of Functions	C++ Python	Note	Medium
614	Average of Levels in Binary Tree	C++ Python	Note	Easy
615	Shopping Offers	C++ Python	Note	Medium
616	Decode Ways II	C++ Python	Note	Hard
617	Solve the Equation	C++ Python	Note	Medium
618	Design Search Autocomplete System	C++ Python	Note	None
619	Maximum Average Subarray I	C++ Python	Note	Easy
620	Maximum Average Subarray II	C++ Python	Note	None
621	Set Mismatch	C++ Python	Note	Easy
622	Maximum Length of Pair Chain	C++ Python	Note	Medium
623	Palindromic Substrings	C++ Python	Note	Medium
624	Replace Words	C++ Python	Note	Medium
625	Dota2 Senate	C++ Python	Note	Medium
626	2 Keys Keyboard	C++ Python	Note	Medium
627	4 Keys Keyboard	C++ Python	Note	None
628	Find Duplicate Subtrees	C++ Python	Note	Medium
629	Two Sum IV - Input is a BST	C++ Python	Note	Easy
630	Maximum Binary Tree	C++ Python	Note	Medium
631	Print Binary Tree	C++ Python	Note	Medium
632	Coin Path	C++ Python	Note	None
633	Judge Route Circle	C++ Python	Note	Easy
634	Find K Closest Elements	C++ Python	Note	Medium
635	Split Array into Consecutive Subsequences	C++ Python	Note	Medium
636	Remove 9	C++ Python	Note	None
637	Image Smoother	C++ Python	Note	Easy
638	Maximum Width of Binary Tree	C++ Python	Note	Medium
639	Equal Tree Partition	C++ Python	Note	None
640	Strange Printer	C++ Python	Note	Hard
641	Non-decreasing Array	C++ Python	Note	Easy
642	Path Sum IV	C++ Python	Note	None
643	Beautiful Arrangement II	C++ Python	Note	Medium
644	Kth Smallest Number in Multiplication Table	C++ Python	Note	Hard
645	Trim a Binary Search Tree	C++ Python	Note	Easy
646	Maximum Swap	C++ Python	Note	Medium
647	Second Minimum Node In a Binary Tree	C++ Python	Note	Easy
648	Bulb Switcher II	C++ Python	Note	Medium
649	Number of Longest Increasing Subsequence	C++ Python	Note	Medium
650	Longest Continuous Increasing Subsequence	C++ Python	Note	Easy
651	Cut Off Trees for Golf Event	C++ Python	Note	Hard
652	Implement Magic Dictionary	C++ Python	Note	Medium
653	Map Sum Pairs	C++ Python	Note	Medium
654	Valid Parenthesis String	C++ Python	Note	Medium
655	24 Game	C++ Python	Note	Hard
656	Valid Palindrome II	C++ Python	Note	Easy
657	Next Closest Time	C++ Python	Note	None
658	Baseball Game	C++ Python	Note	Easy
659	K Empty Slots	C++ Python	Note	None
660	Redundant Connection	C++ Python	Note	Medium
661	Redundant Connection II	C++ Python	Note	Hard
662	Repeated String Match	C++ Python	Note	Easy
663	Longest Univalue Path	C++ Python	Note	Easy
664	Knight Probability in Chessboard	C++ Python	Note	Medium
665	Maximum Sum of 3 Non-Overlapping Subarrays	C++ Python	Note	Hard
666	Employee Importance	C++ Python	Note	Easy
667	Stickers to Spell Word	C++ Python	Note	Hard
668	Top K Frequent Words	C++ Python	Note	Medium
669	Binary Number with Alternating Bits	C++ Python	Note	Easy
670	Number of Distinct Islands	C++ Python	Note	None
671	Max Area of Island	C++ Python	Note	Easy
672	Count Binary Substrings	C++ Python	Note	Easy
673	Degree of an Array	C++ Python	Note	Easy
674	Partition to K Equal Sum Subsets	C++ Python	Note	Medium
675	Falling Squares	C++ Python	Note	Hard
676	Number of Distinct Islands II	C++ Python	Note	None
677	Minimum ASCII Delete Sum for Two Strings	C++ Python	Note	Medium
678	Subarray Product Less Than K	C++ Python	Note	Medium
679	Best Time to Buy and Sell Stock with Transaction Fee	C++ Python	Note	Medium
680	Range Module	C++ Python	Note	Hard
681	Max Stack	C++ Python	Note	None
682	1-bit and 2-bit Characters	C++ Python	Note	Easy
683	Maximum Length of Repeated Subarray	C++ Python	Note	Medium
684	Find K-th Smallest Pair Distance	C++ Python	Note	Hard
685	Longest Word in Dictionary	C++ Python	Note	Easy
686	Accounts Merge	C++ Python	Note	Medium
687	Remove Comments	C++ Python	Note	Medium
688	Candy Crush	C++ Python	Note	None
689	Find Pivot Index	C++ Python	Note	Easy
690	Split Linked List in Parts	C++ Python	Note	Medium
691	Number of Atoms	C++ Python	Note	Hard
692	Minimum Window Subsequence	C++ Python	Note	None
693	Self Dividing Numbers	C++ Python	Note	Easy
694	My Calendar I	C++ Python	Note	Medium
695	Count Different Palindromic Subsequences	C++ Python	Note	Hard
696	My Calendar II	C++ Python	Note	Medium
697	My Calendar III	C++ Python	Note	Hard
698	Flood Fill	C++ Python	Note	Easy
699	Sentence Similarity	C++ Python	Note	Easy
700	Asteroid Collision	C++ Python	Note	Medium
701	Parse Lisp Expression	C++ Python	Note	Hard
702	Sentence Similarity II	C++ Python	Note	Medium
703	Monotone Increasing Digits	C++ Python	Note	Medium
704	Daily Temperatures	C++ Python	Note	Medium
705	Delete and Earn	C++ Python	Note	Medium
706	Cherry Pickup	C++ Python	Note	Hard
707	Closest Leaf in a Binary Tree	C++ Python	Note	New
708	Network Delay Time	C++ Python	Note	New
709	Find Smallest Letter Greater Than Target	C++ Python	Note	New
710	Prefix and Suffix Search	C++ Python	Note	New

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leetcode's Issues

[014. Maximum Subarray]It's DP..not greedy..

Because of the way this algorithm uses optimal substructures (the maximum subarray ending at each position is calculated in a simple way from a related but smaller and overlapping subproblem: the maximum subarray ending at the previous position) this algorithm can be viewed as a simple example of dynamic programming.

From Maximum subarray problem on Wiki

8. String to Integer (atoi) is not found (404)

https://leetcode.com/problems/string-to-integer-atoi/

May I ask you for the solution of problem 8 string-to-integer-atoi ?

learn

026 merge sorted array

a=[4,5,6]
b=[1,2,3,4]
合并后应为[1,2,3,4,5,6]吧
现在为1,2,3,4,4,5,6

How to print binary tree in LeetCode way?

The serialization of a binary tree follows a level order traversal, where '#' signifies a path terminator where no node exists below.
Here's an example:
   1
  / \
 2   3
    /
   4
    \
     5
The above binary tree is serialized as "{1,2,3,#,#,4,#,#,5}".

Question : Give you a binary tree root : TreeNode *p, please print the serialization of tree.

struct TreeNode {
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

How to print undirected graph like LeetCode's serialisation?

OJ's undirected graph serialization:
Nodes are labeled uniquely.

We use # as a separator for each node, and , as a separator for node label and each neighbor of the node.
As an example, consider the serialized graph {0,1,2#1,2#2,2}.

The graph has a total of three nodes, and therefore contains three parts as separated by #.

First node is labeled as 0. Connect node 0 to both nodes 1 and 2.

Second node is labeled as 1. Connect node 1 to node 2.

Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.
Visually, the graph looks like the following:

   1
  / \
 /   \
0 --- 2
     / \
     \_/

Question:
Give you an undirected graph like above, print a string like 0,1,2#1,2#2,2.

Another example: 0,1,5#1,2,5#2,3#3,4,4#4,5,5#5, check this.

Create a LinkedList by initializer_list ?

We always need create some LinkedList in our unit test. Initializer_list is the most easiest way. How to use initializer_list to generate a LinkedList?

For instance:

Input: {1,2,3,4,5,6,7,8,9}
Output: 1->2->3->4->5->6->7->8->9

These codes is in C++? But I feel they are in C, isn't they?

006. Unique Binary Search Trees

这个不一定非要知道卡特兰数才可以搞定. root节点确认,左右两边的数集就确定了.

递归的方式最好理解, 不过会有超时,我也是n=19就挂掉了
用一个全局数组或者map标识一下已经计算过的结果,可以解决这个.
比如这样:

for(int i=1; i<=n; i++) { mpNum[n] += numTrees(i-1)*numTrees(n-i); }

循环也可以解决,但是看了别人的代码总是理解不上去.

以前注册过github就没咋会用, 没找到评论功能, issue是提bug的吧.
可以关闭此条了我就想评论一下.

068. Jump Game

这个题目给的tag是 array greedy , 你这个算法可以归做greedy么?

你这个解法真强大.. 我开始就想偏了, 递归-超时动态规划-超时.
看了你的解法, 我还是想了好几遍才想明白, 厉害! 你这手机三行就ac了

121. Best Time to Buy and Sell Stock II

题目上说不能在买了一个股票未卖出的情况下再继续买另一份股票。

对于数组：4 3 6 7 8 9 10 4 6 3 9

最低为3, 最高是10, 赚了7块. 由于题意没有限制交易次数. 所以我在赚了一发之后, 还可以再玩, 开启上帝视角, 我发现 4买6卖, 3买9卖, 又可以再赚两把. 一共是7 + 2 + 6 = 15块. 有规律么? 貌似低买高卖有一个很重要的前提: 这个区间应该是一个从低到高的有序序列!

这种买卖法是不是行不通？

064. Valid Sudoku

提供个不太实用，但是万一面试官问起来可以扯一扯的方法，算法归为迭代

其实是模拟人在做数独：找到出现频率最多的数字（比如说数字3），遍历没有出现这个数字的小的九宫格，然后对已经存在的数字3分别横向纵向发射，目标九宫格还剩下一个空格没扫射到，那么就填数字3了

以题目为例：
+-----------------+
|5 3 |
|6 | 1 9 5 |
| 9 8 6 |
|8 |-----6-------3|
|4 +---8---3 1|
|7 | * 2 6|
| 6 2 8 |
| 4 1 9 5|
| 8 7 9|
+-----------------+

找到数字3，小九宫格序号分别为 0 1 2 3 4 5 6 7 8，看3号小九宫格，小九宫格内前两行和第二列都被其他的数字3的横向纵向扫射到了，最后只有*这个位置填3了。

实际算法可以采用从数字1遍历到数字9对非存在数字的九宫格扫描，如果还有剩余，那么继续遍历，这个迭代的方式基本上是问题规模逐步减小的，扫描几次后，效率基本上瞬间定位。

所以时间复杂度应该比较小，具体到实现 1到9的位置可以初始就存入map中，小九宫格确定剩余空闲位是否为1时候应该比较繁琐。

027. Symmetric Tree

再提个解法: 中序遍历对于每一层级把数据都存到一个vector中去, 如果元素为null就-1站位, 最终结果就是每个深度从左到右都放到了vector中, 这个就是判断一个int数组是否从中间开始对称了. 没递归优美

这个issues主要是看你描述, 用堆栈来做, 我还没遇到过堆栈解过题, 你方便检索你的记录么, 哪个题目用到了堆栈来搞树的, 我来学习一下.

061. Longest Consecutive Sequence＿时间复杂度

@pezy 你几系出来的，　方法都比较抽象（高效简洁），　前两天每天看一次，都没看懂．　

今天用set实现了下，　再回头看终于明白了．　

如你所说，　直接的思路是排序＋迭代，　无论是map　还是set　都隐含了利用了其自动高效排序的性质优先降低了一次时间复杂度，　如果用了unordered_map，　你还用了默认为０这个性质来去重，　另外加上你用value标识连续数目，直接把代码写成几行了，　赞！

这个issues想和你讨论一下具体的时间复杂度．　每次都不太会分析．

unordered_map 实现：
遍历n，搜了下map内部机制是用　｀红黑树｀　实现？单次增删改按照｀logn来算，　那么总的时间复杂度是不是：　n*logn` ?　　一个循环内部按照logn的线性时间来算.

LeetCode/033. Search for a Range/

class Solution {
    public:
    // 一种新的思路，供大家参考
    // 改进二分查找，并通过修改target的值，使得最多经两次二分查找即可获得元素所在的区间
    // 复杂度O(logn) ~ O(2logn), 处于O(logn)级别，符合题目要求
    // 该算法最后的if-else判断应该还可以改进，如有好的想法请回复
    vector<int> searchRange(vector<int>& nums, int target) {
        if (nums.empty())
            return {-1, -1};
        int min_rank = -1, max_rank = -1;
        int lo = 0, hi = nums.size();
        while (lo < hi) { // 改进二分查找，使其总能返回多个命中元素的秩最大者。耗时O(logn)
            int mi = lo + ((hi - lo) >> 1);
            (target < nums[mi]) ? hi = mi : lo = mi + 1;
        } // 循环结束时，lo为大于target的元素的最小秩，故 --lo 即不大于target的元素的最大秩
        if (--lo != -1 && nums[lo] == target) { // 如target不存在可提前退出
            max_rank = lo; // 此时的lo即为target的最大秩（如存在）
            --target; hi = lo; lo = 0; // 第二次二分查找查找对象变为target - 1，查找区间缩小至[0, max_rank)
            while (lo < hi) { // 耗时O(log(max_rank + 1))
                int mi = lo + ((hi - lo) >> 1);
                (target < nums[mi]) ? hi = mi : lo = mi + 1;
            } // 循环结束时，lo为大于 target - 1 的元素的最小秩，即target的最小秩（如存在）
            min_rank = lo; // 此时的lo即为target的最小秩（如存在）
        }
        if (min_rank == -1)
            return {-1, -1};
        else
            return {min_rank, max_rank};
    }
};

021. Convert Sorted Array to Binary Search Tree

想了好久, 做出来了, 回头看你这实现才5行, 看来刷这个优先想递归.

我就没想可以直接递归.

非递算法是按照这个图示解出的:循环num,所有插入的新节点都是root->right一直right,
然后上去找某个节点的左树left深度小于right的化,那么就可以调整位置了.

http://www.cs.usfca.edu/~galles/visualization/AVLtree.html

031. Generate Parentheses

说明里if (n>0) addParenthesis(str+"(", n-1, m+1);

m+1 应该 m ? 一次左括号右括号只放置一个.

看你代码,原来是实现方式不一样, 我入参都是(n, n)了.

question_064. Valid Sudoku

这个题, 我看标签给的是hash_table
然后我用的是std::map<int, set<int>>来处理的, 那实际上和hash_table没什么关系吧.
即使是unordered_map unordered_set 也是stl内部的数据结构. 不知这题哪里考察hash_table了

067. Search for a Range

针对这种极端情况，我在最开始加上一句判断：
if (A[0] == A[n-1] && A[0] == target) return vector{0, n-1};

仅仅去掉两个元素, 时间复杂度应该没有变吧, 比如元素1和n-2闭区间都是目标元素, 复杂度也是O(n)了
这道题倒是可以实现时间复杂度为2logn

实现一个正常的二分查找, 用于定位是否有目标元素以及定位位置iPos
封装两个二分查找变种, 在[0, iPos] [iPos, n)分别找到(target-1) (target+1)应该插入的位置, 这两个位置就是最后要找到的区间.
这样最坏情况, 步骤1和2各用掉logn时间. 类似这样:

int iPos = binSearch(A, target, 0, n);
int leftPos = binSearch_l(A, target-1, 0, iPos);
int rightPos = binSearch_r(A, target+1, iPos+1, n);

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