203 efficient solutions to LeetCode problems

#	Question	Solution	Difficulty
1	Two Sum	Solution	Easy
2	Add Two Numbers	Solution	Medium
4	Median of Two Sorted Arrays	Solution	Hard
5	Longest Palindromic Substring	Solution	Medium
7	Reverse Integer	Solution	Easy
9	Palindrome Number	Solution	Easy
13	Roman to Integer	Solution	Easy
14	Longest Common Prefix	Solution	Easy
15	3sum	Solution	Medium
16	3sum Closest	Solution	Medium
17	Letter Combinations of a Phone Number	Solution	Medium
19	Remove Nth Node From End of List	Solution	Medium
20	Valid Parentheses	Solution	Easy
21	Merge Two Sorted Lists	Solution	Easy
22	Generate Parentheses	Solution	Medium
23	Merge k Sorted Lists	Solution	Hard
26	Remove Duplicates from Sorted Array	Solution	Easy
27	Remove Element	Solution	Easy
28	Implement strStr()	Solution	Easy
33	Search in Rotated Sorted Array	Solution	Medium
34	Find First and Last Position of Element in Sorted Array	Solution	Medium
35	Search Insert Position	Solution	Easy
38	Count and Say	Solution	Easy
42	Trapping Rain Water	Solution	Hard
46	Permutations	Solution	Medium
47	Permutations II	Solution	Medium
48	Rotate Image	Solution	Medium
49	Group Anagrams	Solution	Medium
51	N-Queens	Solution	Hard
52	N-Queens II	Solution	Hard
53	Maximum Subarray	Solution	Easy
55	Jump Game	Solution	Medium
58	Length of Last Word	Solution	Easy
62	Unique Paths	Solution	Medium
63	Unique Paths II	Solution	Medium
66	Plus One	Solution	Easy
67	Add Binary	Solution	Easy
69	Sqrt(x)	Solution	Easy
70	Climbing Stairs	Solution	Easy
73	Set Matrix Zeroes	Solution	Medium
78	Subsets	Solution	Medium
80	Remove Duplicates from Sorted Array II	Solution	Medium
81	Search in Rotated Sorted Array II	Solution	Medium
82	Remove Duplicates from Sorted List II	Solution	Medium
83	Remove Duplicates from Sorted List	Solution	Easy
88	Merge Sorted Array	Solution	Easy
90	Subsets II	Solution	Medium
92	Reverse Linked List II	Solution	Medium
94	Binary Tree Inorder Traversal	Solution	Medium
98	Validate Binary Search Tree	Solution	Medium
100	Same Tree	Solution	Easy
101	Symmetric Tree	Solution	Easy
102	Binary Tree Level Order Traversal	Solution	Medium
104	Maximum Depth of Binary Tree	Solution	Easy
107	Binary Tree Level Order Traversal II	Solution	Easy
108	Convert Sorted Array to Binary Search Tree	Solution	Easy
110	Balanced Binary Tree	Solution	Easy
111	Minimum Depth of Binary Tree	Solution	Easy
118	Pascal's Triangle	Solution	Easy
119	Pascal's Triangle II	Solution	Easy
121	Best Time to Buy and Sell Stock	Solution	Easy
122	Best Time to Buy and Sell Stock II	Solution	Easy
125	Valid Palindrome	Solution	Easy
127	Word Ladder	Solution	Medium
136	Single Number	Solution	Easy
139	Word Break	Solution	Medium
141	Linked List Cycle	Solution	Easy
142	Linked List Cycle II	Solution	Medium
143	Reorder List	Solution	Medium
144	Binary Tree Preorder Traversal	Solution	Medium
145	Binary Tree Postorder Traversal	Solution	Hard
146	LRU Cache	Solution	Medium
148	Sort List	Solution	Medium
149	Max Points on a Line	Solution	Hard
151	Reverse Words in a String	Solution	Medium
155	Min Stack	Solution	Easy
160	Intersection of Two linked Lists	Solution	Easy
162	Find Peak Element	Solution	Medium
167	Two Sum II - Input array is sorted	Solution	Easy
168	Excel Sheet Column Title	Solution	Easy
169	Majority Element	Solution	Easy
171	Excel Sheet Column Number	Solution	Easy
172	Factorial Trailing Zeroes	Solution	Easy
175	Combine Two Tables	Solution	Easy
176	Second Highest Salary	Solution	Easy
177	Nth Highest Salary	Solution	Medium
178	Rank Scores	Solution	Medium
180	Consecutive Numbers	Solution	Medium
181	Employees Earning More Than Their Managers	Solution	Easy
182	Duplicate Emails	Solution	Easy
183	Customers Who Never Order	Solution	Easy
184	Department Highest Salary	Solution	Medium
185	Department Top Three Salaries	Solution	Hard
189	Rotate Array	Solution	Easy
190	Reverse Bits	Solution	Easy
191	Number of 1 Bits	Solution	Easy
196	Delete Duplicate Emails	Solution	Easy
197	Rising Temperature	Solution	Easy
198	House Robber	Solution	Easy
200	Number of Islands	Solution	Medium
202	Happy Number	Solution	Easy
203	Remove Linked List Elements	Solution	Easy
204	Count Primes	Solution	Easy
206	Reverse Linked List	Solution	Easy
207	Course Schedule	Solution	Medium
208	Implement Trie (Prefix Tree)	Solution	Medium
210	Course Schedule II	Solution	Medium
217	Contains Duplicate	Solution	Easy
226	Invert Binary Tree	Solution	Easy
231	Power of Two	Solution	Easy
232	Implement Queue using Stacks	Solution	Easy
234	Palindrome Linked List	Solution	Easy
235	Lowest Common Ancestor of a Binary Search Tree	Solution	Easy
236	Lowest Common Ancestor of a Binary Tree	Solution	Medium
237	Delete Node in a Linked List	Solution	Easy
238	Product of Array Except Self	Solution	Medium
239	Sliding Window Maximum	Solution	Hard
240	Search a 2D Matrix II	Solution	Medium
242	Valid Anagram	Solution	Easy
262	Trips and Users	Solution	Hard
263	Ugly Number	Solution	Easy
264	Ugly Number II	Solution	Medium
268	Missing Number	Solution	Easy
273	Integer to English Words	Solution	Hard
278	First Bad Version	Solution	Easy
283	Move Zeroes	Solution	Easy
290	Word Pattern	Solution	Easy
292	Nim Game	Solution	Easy
295	Find Median from Data Stream	Solution	Hard
300	Longest Increasing Subsequence	Solution	Medium
303	Range Sum Query - Immutable	Solution	Easy
309	Best Time to Buy and Sell Stock with Cooldown	Solution	Medium
326	Power of Three	Solution	Easy
328	Odd Even Linked List	Solution	Medium
342	Power of Four	Solution	Easy
344	Reverse String	Solution	Easy
347	Top K Frequent Elements	Solution	Medium
349	Intersection of Two Arrays	Solution	Easy
350	Intersection of Two Arrays II	Solution	Easy
354	Russian Doll Envelopes	Solution	Hard
367	Valid Perfect Square	Solution	Easy
371	Sum of Two Integers	Solution	Easy
380	Insert Delete GetRandom O(1)	Solution	Medium
381	Insert Delete GetRandom O(1) - Duplicates allowed	Solution	Hard
383	Ransom Note	Solution	Easy
384	Shuffle an Array	Solution	Medium
387	First Unique Character in a String	Solution	Easy
389	Find the Difference	Solution	Easy
412	Fizz Buzz	Solution	Easy
414	Third Maximum Number	Solution	Easy
429	N-ary Tree Level Order Traversal	Solution	Easy
437	Path Sum III	Solution	Easy
442	Find All Duplicates in an Array	Solution	Medium
443	String Compression	Solution	Easy
445	Add Two Numbers II	Solution	Medium
448	Find All Numbers Disappeared in an Array	Solution	Easy
454	4Sum II	Solution	Medium
461	Hamming Distance	Solution	Easy
470	Implement Rand10() Using Rand7()	Solution	Medium
477	Total Hamming Distance	Solution	Medium
480	Sliding Window Median	Solution	Hard
500	Keyboard Row	Solution	Easy
509	Fibonacci Number	Solution	Easy
516	Longest Palindromic Subsequence	Solution	Medium
518	Coin Change 2	Solution	Medium
520	Detect Capital	Solution	Easy
525	Contiguous Array	Solution	Medium
543	Diameter of Binary Tree	Solution	Easy
559	Maximum Depth of N-ary Tree	Solution	Easy
560	Subarray Sum Equals K	Solution	Medium
572	Subtree of Another Tree	Solution	Easy
581	Shortest Unsorted Continuous Subarray	Solution	Easy
589	N-ary Tree Preorder Traversal	Solution	Easy
590	N-ary Tree Postorder Traversal	Solution	Easy
595	Big Countries	Solution	Easy
596	Classes More Than 5 Students	Solution	Easy
601	Human Traffic of Stadium	Solution	Hard
617	Merge Two Binary Trees	Solution	Easy
620	Not Boring Movies	Solution	Easy
626	Exchange Seats	Solution	Medium
627	Swap Salary	Solution	Easy
692	Top K Frequent Words	Solution	Medium
695	Max Area of Island	Solution	Medium
703	Kth Largest Element in a Stream	Solution	Easy
704	Binary Search	Solution	Easy
706	Design HashMap	Solution	Easy
707	Design Linked List	Solution	Easy
709	To Lower Case	Solution	Easy
733	Flood Fill	Solution	Easy
771	Jewels and Stones	Solution	Easy
895	Maximum Frequency Stack	Solution	Hard
912	Sort an Array	Solution	Medium
976	Largest Perimeter Triangle	Solution	Easy
1010	Pairs of Songs With Total Durations Divisible by 60	Solution	Easy
1092	Shortest Common Supersequence	Solution	Hard
1114	Print in Order	Solution	Easy
1115	Print FooBar Alternately	Solution	Medium
1116	Print Zero Even Odd	Solution	Medium
1117	Building H2O	Solution	Medium
1139	Largest 1-Bordered Square	Solution	Medium
1179	Reformat Department Table	Solution	Easy
1195	Fizz Buzz Multithreaded	Solution	Medium
1207	Unique Number of Occurrences	Solution	Easy