LeetCode OJ Solution

Progress // 当前进度

	LeetCode#	CCI*	COF**
	1444 (8)	109	75
	53 (2)	2	2
	95 (3)	2	2
	26 (0)	1	1
	174 (5)	5	5

• # Some problems are locked by leetcode. The number in brackets is solved. // 部分题目被锁，括号内是其数目
• * CCI is the abbreviation of "Cracking the Coding Interview", here is the portal // CCI 是《程序员面试金典》的题库，传送链接已附上
• ** COF is the abbreviation of "Coding Interviews: Questions, Analysis and Solutions", here is the portal // COF 是《剑指 Offer（第 2 版）》的题库，传送链接已附上

Solutions // 刷题成果

• LeetCode (Total):
  

• LeetCode Locked Problems:

• CCI:

• COF:

• Unreleased: None

• The C++ solution is currently the way I work through the Leetcode // 我现在主要用 C++ 刷题

• Haskell solution is just for fun :) // 偶尔也会用 Haskell 水一些题

• The Archive Unreleased is for some problem somehow it shows up for practicing but does not list up in the problem set. It is rare to find one, and it will be moved into the problem set after its release.

Solved Problem List // 题目列表

Archive	AC/TTL	Archive	AC/TTL	Archive	AC/TTL	Archive	AC/TTL
0	52	1	29	2	24/99(0/1)	3	13/99(0/1)
4	10/99(0/1)	5	7	6	3	7	6
8	6	9	5	10	7	11	4
12	2	13	0	14	1/95(5/5)

• Each Archive contains 100 problems.
• several questions were locked, pattern a/b (c/d) means that accepted a problems within b problems, moveover, accepted c locked problems within d problems.

Archive#00: Problem 001 ~ Problem 100

ID	Difficulty	Problem	cpp	python	ruby	java
001	Easy	Two Sum	⭕	⭕	⭕
002	Medium	Add Two Numbers	⭕	⭕	⭕
003	Medium	Longest Substring Without Repeating Characters	⭕
004	Hard	Median of Two Sorted Arrays	⭕	⭕	⭕
005	Medium	Longest Palindromic Substring	⭕		⭕
006	Hard	ZigZag Conversion	⭕	⭕	⭕
007	Easy	Reverse Integer	⭕
008	Medium	String to Integer (atoi)	⭕
009	Easy	Palindrome Number	⭕
010	Hard	Regular Expression Matching	⭕
011	Medium	Container With Most Water	⭕
012	Medium	Integer to Roman	⭕
013	Easy	Roman to Integer	⭕
014	Easy	Longest Common Prefix	⭕
015	Medium	3Sum	⭕
016	Medium	3Sum Closest	⭕
017	Medium	Letter Combinations of a Phone Number	⭕	⭕	⭕
019	Medium	Remove Nth Node From End of List	⭕	⭕	⭕
020	Easy	Valid Parentheses	⭕
021	Easy	Merge Two Sorted Lists	⭕		⭕
022	Medium	Valid Parentheses	⭕
023	Hard	Merge k Sorted Lists	⭕	⭕	⭕
024	Medium	Swap Nodes in Pairs	⭕		⭕
025	Hard	Reverse Nodes in k-Group	⭕
029	Medium	Divide Two Integers	⭕
031	Medium	Next Permutation	⭕	⭕
032	Hard	Longest Valid Parentheses	⭕	⭕
033	Medium	Search in Rotated Sorted Array	⭕
039	Medium	Combination Sum	⭕
042	Hard	Trapping Rain Water	⭕	⭕	⭕
044	Hard	Wildcard Matching	⭕
045	Hard	Jump Game II	⭕
046	Medium	Permutations	⭕
049	Medium	Group Anagrams	⭕	⭕	⭕
050	Medium	Pow(x, n)	⭕
053	Easy	Maximum Subarray	⭕	⭕	⭕
055	Medium	Jump Game	⭕
056	Medium	Merge Intervals	⭕
061	Medium	Rotate List	⭕		⭕
064	Medium	Minimum Path Sum	⭕
065	Hard	Valid Number	⭕	⭕	⭕
068	Hard	Text Justification	⭕	⭕
069	Easy	Sqrt(x)	⭕
072	Hard	Edit Distance	⭕
074	Medium	Search a 2D Matrix	⭕
081	Medium	Search in Rotated Sorted Array II	⭕
082	Medium	Remove Duplicates from Sorted List II	⭕	⭕	⭕	⭕
083	Easy	Remove Duplicates from Sorted List	⭕	⭕	⭕	⭕
086	Medium	Partition List	⭕	⭕	⭕	⭕
091	Medium	Decode Ways	⭕
093	Medium	Restore IP Addresses	⭕
098	Medium	Validate Binary Search Tree	⭕
100

Archive#01: Problem 101 ~ Problem 200

ID	Difficulty	Problem	cpp	python	ruby	java
104	Easy	Maximum Depth of Binary Tree	⭕	⭕	⭕
121	Easy	Best Time to Buy and Sell Stock	⭕
122	Easy	Best Time to Buy and Sell Stock II	⭕	⭕
123	Hard	Best Time to Buy and Sell Stock III	⭕
124	Hard	Binary Tree Maximum Path Sum	⭕
125	Easy	Valid Palindrome	⭕	⭕	⭕
126	Hard	Word Ladder II	⭕
127	Medium	Word Ladder	⭕
130	Medium	Surrounded Regions	⭕
133	Medium	Clone Graph	⭕
136	Easy	Single Number	⭕	⭕	⭕
137	Medium	Single Number II	⭕	⭕	⭕
139	Medium	Word Break	⭕
141	Easy	Linked List Cycle	⭕
142	Medium	Linked List Cycle II	⭕
143	Medium	Reorder List	⭕
146	Medium	Evaluate Reverse Polish Notation	⭕
149	Hard	Max Points on a Line	⭕
150	Medium	Evaluate Reverse Polish Notation	⭕
151	Medium	Reverse Words in a String	⭕
152	Easy	Maximum Subarray	⭕	⭕	⭕
155	Medium	Min Stack	⭕
165	Medium	Compare Version Numbers	⭕
166	Medium	Fraction to Recurring Decimal	⭕
169	Easy	Majority Element	⭕	⭕
188	Hard	Best Time to Buy and Sell Stock IV	⭕
189	Easy	Rotate Array	⭕	⭕	⭕
199	Medium	Binary Tree Right Side View	⭕		⭕
200	Medium	Number of Islands	⭕

Archive#02: Problem 201 ~ Problem 300

ID	Difficulty	Problem	cpp	python	ruby	java
201	Medium	Bitwise AND of Numbers Range	⭕		⭕
202	Easy	Happy Number	⭕	⭕	⭕
204	Easy	Count Primes	⭕
208	Medium	Implement Trie (Prefix Tree)	⭕
211	Medium	Add and Search Word - Data structure design	⭕
218	Hard	The Skyline Problem	⭕
220	Medium	Contains Duplicate III	⭕
221	Medium	Maximal Square	⭕
224	Hard	Basic Calculator	⭕
225	Easy	Implement Stack using Queues	⭕
226	Easy	Invert Binary Tree	⭕		⭕
227	Medium	Basic Calculator II	⭕
231	Easy	Power of Two	⭕		⭕
235	Easy	Lowest Common Ancestor of a Binary Search Tree	⭕	⭕	⭕
236	Medium	Lowest Common Ancestor of a Binary Tree	⭕
238	Medium	Product of Array Except Self	⭕
241	Medium	Different Ways to Add Parentheses	⭕	⭕	⭕
260	Medium	Single Number III	⭕	⭕	⭕
273	Hard	Integer to English Words	⭕
278	Easy	First Bad Version	⭕
279	Medium	Perfect Squares	⭕
283	Easy	Move Zeroes	⭕	⭕	⭕
289	Medium	Game of Life	⭕
300	Medium	Longest Increasing Subsequence	⭕	⭕

Archive#03: Problem 301 ~ Problem 400

ID	Difficulty	Problem	cpp	python	ruby	java
306	Medium	Additive Number	⭕	⭕
307	Medium	Range Sum Query - Mutable	⭕
309	Medium	Best Time to Buy and Sell Stock with Cooldown	⭕
315	Hard	Count of Smaller Numbers After Self	⭕
318	Medium	Maximum Product of Word Lengths	⭕
327	Hard	Count of Range Sum	⭕
355	Medium	Design Twitter	⭕
365	Medium	Water and Jug Problem	⭕	⭕
367	Easy	Valid Perfect Square	⭕
383	Easy	Ransom Note	⭕
385	Medium	Mini Parser	⭕	⭕	⭕
387	Easy	First Unique Character in a String	⭕
394	Medium	Decode String	⭕	⭕	⭕
400

Archive#04: Problem 401 ~ Problem 500

ID	Difficulty	Problem	cpp	python	ruby	java
409	Easy	Longest Palindrome	⭕	⭕	⭕
415	Easy	Add Strings	⭕	⭕
420	Hard	Strong Password Checker	⭕
445	Medium	Add Two Numbers II	⭕
464	Medium	Can I Win	⭕
466	Hard	Count The Repetitions	⭕
468	Medium	Validate IP Address	⭕
476	Easy	Number Complement	⭕
493	Hard	Reverse Pairs	⭕
494	Medium	Target Sum	⭕
500

Archive#05: Problem 501 ~ Problem 600

ID	Difficulty	Problem	cpp	python	ruby	java
525	Medium	Contiguous Array	⭕
540	Medium	Single Element in a Sorted Array	⭕		⭕
541	Easy	Reverse String II	⭕
542	Medium	01 Matrix	⭕
543	Easy	Diameter of Binary Tree	⭕	⭕
560	Medium	Subarray Sum Equals K	⭕
572	Easy	Subtree of Another Tree	⭕
600

Archive#06: Problem 601 ~ Problem 700

ID	Difficulty	Problem	cpp	python	ruby	java
622	Medium	Design Circular Queue	⭕
678	Medium	Valid Parenthesis String	⭕
695	Medium	Max Area of Island	⭕
700

Archive#07: Problem 701 ~ Problem 800

ID	Difficulty	Problem	cpp	python	ruby	java
714	Medium	Best Time to Buy and Sell Stock with Transaction Fee	⭕
733	Easy	Flood Fill	⭕
735	Medium	Asteroid Collision	⭕
739	Medium	Daily Temperatures	⭕
752	Medium	Open the Lock	⭕
771	Easy	Jewels and Stones	⭕
800

Archive#08: Problem 801 ~ Problem 900

ID	Difficulty	Problem	cpp	python	ruby	java
820	Medium	Short Encoding of Words	⭕
836	Easy	Rectangle Overlap	⭕	⭕	⭕
844	Easy	Backspace String Compare	⭕	⭕	⭕
876	Easy	Middle of the Linked List	⭕
887	Easy	Super Egg Drop	⭕
892	Easy	Surface Area of 3D Shapes	⭕
900

Archive#09: Problem 901 ~ Problem 1000

ID	Difficulty	Problem	cpp	python	ruby	java
912	Medium	Sort an Array	⭕	⭕	⭕	⭕
945	Medium	Minimum Increment to Make Array Unique	⭕
983	Medium	Minimum Cost For Tickets	⭕
993	Easy	Cousins in Binary Tree	⭕
997	Easy	Find the Town Judge	⭕
1000

Archive#10: Problem 1001 ~ Problem 1100

ID	Difficulty	Problem	cpp	python	ruby	java
1008	Medium	Construct Binary Search Tree from Preorder Traversal	⭕
1009	Easy	Complement of Base 10 Integer	⭕
1013	Easy	Partition Array Into Three Parts With Equal Sum	⭕	⭕
1046	Easy	Last Stone Weight	⭕
1049	Medium	Last Stone Weight II	⭕
1071	Easy	Greatest Common Divisor of Strings	⭕	⭕
1095	Hard	Find in Mountain Array	⭕
1100

Archive#11: Problem 1101 ~ Problem 1200

ID	Difficulty	Problem	cpp	python	ruby	java
1111	Medium	Maximum Nesting Depth of Two Valid Parentheses Strings	⭕	⭕	⭕
1143	Medium	Longest Common Subsequence	⭕
1160	Easy	Find Words That Can Be Formed by Characters	⭕	⭕
1162	Medium	As Far from Land as Possible	⭕
1200

Archive#12: Problem 1201 ~ Problem 1300

ID	Difficulty	Problem	cpp	python	ruby	java
1232	Easy	Check If It Is a Straight Line	⭕
1248	Medium	Count Number of Nice Subarrays	⭕
1300

Archive#13: Problem 1301 ~ Problem 1400

ID	Difficulty	Problem	cpp	python	ruby	java
1400

Archive#14: Problem 1401 ~ Problem 1500

ID	Difficulty	Problem	cpp	python	ruby	java
1415	Medium	The k-th Lexicographical String of All Happy Strings of Length n	⭕
1426	Easy	Counting Elements	⭕	⭕	⭕
1427	Easy	Perform String Shifts	⭕	⭕	⭕
1428	Medium	Leftmost Column with at Least a One	⭕
1429	Medium	First Unique Number	⭕
1430	Medium	Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree	⭕
1500

Locked LeetCode Problems (8)

• Solved
  • 1426 - Counting Elements
  • 1427 - Perform String Shifts
  • 1428 - Leftmost Column with at Least a One
  • 1429 - First Unique Number
  • 1430 - Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree
• Finded but without permission
  • 288 - Unique Word Abbreviation
  • 308 - Range Sum Query 2D - Mutable
  • 444 - Sequence Reconstruction

Archive#CCI

ID	Difficulty	Problem	cpp	python	ruby	java
面试题 01.06	Easy	字符串压缩	⭕
面试题 01.07	Medium	旋转矩阵	⭕
面试题 08.11	Medium	硬币	⭕
面试题 16.03	Hard	交点	⭕
面试题 17.16	Easy	按摩师	⭕

Archive#COF

ID	Difficulty	Problem	cpp	python	ruby	java
面试题 13	Medium	机器人的运动范围	⭕
面试题 40	Easy	最小的 k 个数	⭕
面试题 51	Hard	数组中的逆序对	⭕
面试题 56-I	Medium	数组中数字出现的次数	⭕
面试题 62	Easy	圆圈中最后剩下的数字	⭕

Tags // 标签分类

Programming Fundamentals // 编程基础

• (37): 001, 004, 011, 015, 016, 031, 033, 039, 042, 045, 053, 055, 056, 064, 074, 081, 121, 122, 123, 126, 152, 169, 189, 238, 283, 289, 560, 695, 714, 945, 1013, 1160, 1232, 1426, 1427, 1428, cci0107
• (35): 003, 005, 006, 008, 010, 012, 013, 014, 017, 020, 022, 032, 044, 049, 065, 068, 072, 091, 093, 125, 126, 151, 165, 227, 273, 383, 385, 387, 415, 468, 541, 678, 1071, 1415, cci0106
• (12): 098, 104, 124, 199, 226, 235, 236, 543, 572, 993, 1008, 1430
• (8): 136, 137, 169, 201, 231, 260, 318, 476

Algorithm // 算法

• (11): 010, 017, 022, 039, 044, 046, 093, 126, 211, 306, 1415
• (16): 004, 029, 033, 050, 069, 074, 081, 278, 300, 315, 327, 367, 493, 887, 1095, 1111
• (11): 126, 127, 130, 133, 199, 200, 279, 542, 752, 993, 1162
• (12): 098, 104, 124, 130, 133, 199, 200, 394, 494, 542, 695, 733
• (10): 004, 023, 053, 169, 218, 241, 315, 327, 493, cof40
• (27): 005, 010, 032, 044, 053, 064, 072, 091, 121, 123, 139, 152, 188, 221, 279, 300, 309, 464, 466, 494, 714, 887, 983, 1049, 1143, cci0811, cci1716
• (7): 044, 045, 055, 122, 714, 1046, 1111
• (1): 218
• (13): 003, 011, 015, 016, 019, 042, 061, 086, 125, 142, 283, 844, 1248
• (1): 003
• (5): 056, 220, 315, 327, 493

Data Structure // 数据结构

• (5): 218, 307, 315, 327, 493
• (3): 133, 997, 1162
• (17): 001, 003, 049, 136, 149, 166, 202, 204, 355, 387, 409, 525, 560, 739, 771, 1160, 1429
• (5): 023, 218, 355, 1046, cof40
• (15): 002, 019, 021, 023, 024, 025, 061, 082, 083, 086, 141, 142, 143, 445, 876
• (1): 220
• (1): 622
• (5): 218, 307, 315, 327, 493
• (11): 020, 042, 150, 155, 224, 225, 385, 394, 735, 739, 844
• (2): 208, 211
• (2): 130, 200

Math, Arithmetic, Game Theory // 数学相关

• (27): 002, 007, 008, 009, 012, 013, 029, 050, 065, 069, 149, 166, 202, 204, 224, 231, 273, 279, 365, 367, 836, 887, 892, 1009, 1232, 1427, cci1603
• (3): 892, 1232, cci1603
• (1): 464

High-level Programming Techniques // 编程技巧

• (8): 146, 155, 208, 211, 225, 355, 622, 1429

Un-taged (by LeetCode)

Several questions were not attaching any tags by the LeetCode. So I mark them with my tags (green colored) for looking them over. It may be a thinking way, a concept, a programming technique, or a data structure. // 部分题目并没有给出官方的标签，所以我自作主张给了一份绿色标签，包括思维方式、概念、编程技巧或特殊数据结构。

• (1): 540
• (2): 540, cof56a
• (1): 912
• (1): cof62
• (1): 912, cof51
• (1): 912
• (1): cof13
• (1): 912
• (1): cof62
• (1): 420, 820
• (1): 820

License

This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.