LeetCode

LeetCode Problems

#	Title	Solution	Note	Difficulty
1	Two Sum	Java	Note	Easy
2	Add Two Numbers	Java	Note	Medium
3	Longest Substring Without Repeating Characters	Java	Note	Medium
4	Median of Two Sorted Arrays	Java	Note	Hard
5	Longest Palindromic Substring	Java	Note	Medium
6	ZigZag Conversion	Java	Note	Medium
7	Reverse Integer	Java	Note	Easy
8	String to Integer (atoi)	Java	Note	Medium
9	Palindrome Number	Java	Note	Easy
11	Container With Most Water	Java	Note	Medium
12	Integer to Roman	Java	Note	Medium
13	Roman to Integer	Java	Note	Easy
14	Longest Common Prefix	Java	Note	Easy
15	3Sum	Java	Note	Medium
16	3Sum Closest	Java	Note	Medium
17	Letter Combinations of a Phone Number	Java	Note	Medium
18	4Sum	Java	Note	Medium
19	Remove Nth Node From End of List	Java	Note	Medium
20	Valid Parentheses	Java	Note	Easy
21	Merge Two Sorted Lists	Java	Note	Easy
22	Generate Parentheses	Java	Note	Medium
23	Merge k Sorted Lists	Java	Note	Hard
24	Swap Nodes in Pairs	Java	Note	Medium
26	Remove Duplicates from Sorted Array	Java	Note	Easy
27	Remove Element	Java	Note	Easy
28	Implement strStr()	Java	Note	Easy
29	Divide Two Integers	Java	Note	Medium
31	Next Permutation	Java	Note	Medium
33	Search in Rotated Sorted Array	Java	Note	Medium
34	Find First and Last Position of Element in Sorted Array	Java	Note	Medium
35	Search Insert Position	Java	Note	Easy
36	Valid Sudoku	Java	Note	Medium
38	Count and Say	Java	Note	Easy
39	Combination Sum	Java	Note	Medium
40	Combination Sum II	Java	Note	Medium
41	First Missing Positive	Java	Note	Hard
42	Trapping Rain Water	Java	Note	Hard
43	Multiply Strings	Java	Note	Medium
45	Jump Game II	Java	Note	Hard
46	Permutations	Java	Note	Medium
47	Permutations II	Java	Note	Medium
48	Rotate Image	Java	Note	Medium
49	Group Anagrams	Java	Note	Medium
50	Pow(x, n)	Java	Note	Medium
51	N-Queens	Java	Note	Hard
52	N-Queens II	Java	Note	Hard
53	Maximum Subarray	Java	Note	Easy
54	Spiral Matrix	Java	Note	Medium
55	Jump Game	Java	Note	Medium
56	Merge Intervals	Java	Note	Medium
58	Length of Last Word	Java	Note	Easy
59	Spiral Matrix II	Java	Note	Medium
60	Permutation Sequence	Java	Note	Medium
61	Rotate List	Java	Note	Medium
62	Unique Paths	Java	Note	Medium
63	Unique Paths II	Java	Note	Medium
64	Minimum Path Sum	Java	Note	Medium
66	Plus One	Java	Note	Easy
67	Add Binary	Java	Note	Easy
69	Sqrt(x)	Java	Note	Easy
70	Climbing Stairs	Java	Note	Easy
71	Simplify Path	Java	Note	Medium
73	Set Matrix Zeroes	Java	Note	Medium
75	Sort Colors	Java	Note	Medium
76	Minimum Window Substring	Java	Note	Hard
77	Combinations	Java	Note	Medium
78	Subsets	Java	Note	Medium
79	Word Search	Java	Note	Medium
80	Remove Duplicates from Sorted Array II	Java	Note	Medium
81	Search in Rotated Sorted Array II	Java	Note	Medium
82	Remove Duplicates from Sorted List II	Java	Note	Medium
83	Remove Duplicates from Sorted List	Java	Note	Easy
86	Partition List	Java	Note	Medium
88	Merge Sorted Array	Java	Note	Easy
89	Gray Code	Java	Note	Medium
90	Subsets II	Java	Note	Medium
91	Decode Ways	Java	Note	Medium
92	Reverse Linked List II	Java	Note	Medium
93	Restore IP Addresses	Java	Note	Medium
94	Binary Tree Inorder Traversal	Java	Note	Medium
96	Unique Binary Search Trees	Java	Note	Medium
98	Validate Binary Search Tree	Java	Note	Medium
100	Same Tree	Java	Note	Easy
101	Symmetric Tree	Java	Note	Easy
102	Binary Tree Level Order Traversal	Java	Note	Medium
103	Binary Tree Zigzag Level Order Traversal	Java	Note	Medium
104	Maximum Depth of Binary Tree	Java	Note	Easy
105	Construct Binary Tree from Preorder and Inorder Traversal	Java	Note	Medium
106	Construct Binary Tree from Inorder and Postorder Traversal	Java	Note	Medium
107	Binary Tree Level Order Traversal II	Java	Note	Easy
108	Convert Sorted Array to Binary Search Tree	Java	Note	Easy
109	Convert Sorted List to Binary Search Tree	Java	Note	Medium
110	Balanced Binary Tree	Java	Note	Easy
111	Minimum Depth of Binary Tree	Java	Note	Easy
112	Path Sum	Java	Note	Easy
113	Path Sum II	Java	Note	Medium
114	Flatten Binary Tree to Linked List	Java	Note	Medium
116	Populating Next Right Pointers in Each Node	Java	Note	Medium
117	Populating Next Right Pointers in Each Node II	Java	Note	Medium
118	Pascal’s Triangle	Java	Note	Easy
119	Pascal’s Triangle II	Java	Note	Easy
120	Triangle	Java	Note	Medium
121	Best Time to Buy and Sell Stock	Java	Note	Easy
122	Best Time to Buy and Sell Stock II	Java	Note	Easy
123	Best Time to Buy and Sell Stock III	Java	Note	Hard
125	Valid Palindrome	Java	Note	Easy
127	Word Ladder	Java	Note	Medium
129	Sum Root to Leaf Numbers	Java	Note	Medium
130	Surrounded Regions	Java	Note	Medium
131	Palindrome Partitioning	Java	Note	Medium
133	Clone Graph	Java	Note	Medium
134	Gas Station	Java	Note	Medium
136	Single Number	Java	Note	Easy
138	Copy List with Random Pointer	Java	Note	Medium
139	Word Break	Java	Note	Medium
141	Linked List Cycle	Java	Note	Easy
142	Linked List Cycle II	Java	Note	Medium
146	LRU Cache	Java	Note	Medium
148	Sort List	Java	Note	Medium
150	Evaluate Reverse Polish Notation	Java	Note	Medium
152	Maximum Product Subarray	Java	Note	Medium
155	Min Stack	Java	Note	Easy
160	Intersection of Two Linked Lists	Java	Note	Easy
162	Find Peak Element	Java	Note	Medium
166	Fraction to Recurring Decimal	Java	Note	Medium
167	Two Sum II - Input array is sorted	Java	Note	Easy
169	Majority Element	Java	Note	Easy
171	Excel Sheet Column Number	Java	Note	Easy
172	Factorial Trailing Zeroes	Java	Note	Easy
175	Combine Two Tables	SQL	Note	Easy
176	Second Highest Salary	SQL	Note	Easy
179	Largest Number	Java	Note	Medium
188	Best Time to Buy and Sell Stock IV	Java	Note	Hard
189	Rotate Array	Java	Note	Easy
190	Reverse Bits	Java	Note	Easy
191	Number of 1 Bits	Java	Note	Easy
198	House Robber	Java	Note	Easy
200	Number of Islands	Java	Note	Medium
202	Happy Number	Java	Note	Easy
204	Count Primes	Java	Note	Easy
206	Reverse Linked List	Java	Note	Easy
207	Course Schedule	Java	Note	Medium
208	Implement Trie (Prefix Tree)	Java	Note	Medium
210	Course Schedule II	Java	Note	Medium
215	Kth Largest Element in an Array	Java	Note	Medium
217	Contains Duplicate	Java	Note	Easy
221	Maximal Square	Java	Note	Medium
226	Invert Binary Tree	Java	Note	Easy
227	Basic Calculator II	Java	Note	Medium
230	Kth Smallest Element in a BST	Java	Note	Medium
234	Palindrome Linked List	Java	Note	Easy
236	Lowest Common Ancestor of a Binary Tree	Java	Note	Medium
237	Delete Node in a Linked List	Java	Note	Easy
238	Product of Array Except Self	Java	Note	Medium
239	Sliding Window Maximum	Java	Note	Hard
240	Search a 2D Matrix II	Java	Note	Medium
242	Valid Anagram	Java	Note	Easy
268	Missing Number	Java	Note	Easy
279	Perfect Squares	Java	Note	Medium
283	Move Zeroes	Java	Note	Easy
287	Find the Duplicate Number	Java	Note	Medium
289	Game of Life	Java	Note	Medium
300	Longest Increasing Subsequence	Java	Note	Medium
309	Best Time to Buy and Sell Stock with Cooldown	Java	Note	Medium
322	Coin Change	Java	Note	Medium
324	Wiggle Sort II	Java	Note	Medium
326	Power of Three	Java	Note	Easy
328	Odd Even Linked List	Java	Note	Medium
334	Increasing Triplet Subsequence	Java	Note	Medium
337	House Robber III	Java	Note	Medium
338	Counting Bits	Java	Note	Medium
341	Flatten Nested List Iterator	Java	Note	Medium
344	Reverse String	Java	Note	Easy
347	Top K Frequent Elements	Java	Note	Medium
350	Intersection of Two Arrays II	Java	Note	Easy
371	Sum of Two Integers	Java	Note	Easy
378	Kth Smallest Element in a Sorted Matrix	Java	Note	Medium
380	Insert Delete GetRandom O(1)	Java	Note	Medium
384	Shuffle an Array	Java	Note	Medium
387	First Unique Character in a String	Java	Note	Easy
394	Decode String	Java	Note	Medium
395	Longest Substring with At Least K Repeating Characters	Java	Note	Medium
406	Queue Reconstruction by Height	Java	Note	Medium
412	Fizz Buzz	Java	Note	Easy
416	Partition Equal Subset Sum	Java	Note	Medium
437	Path Sum III	Java	Note	Easy
438	Find All Anagrams in a String	Java	Note	Medium
448	Find All Numbers Disappeared in an Array	Java	Note	Easy
454	4Sum II	Java	Note	Medium
494	Target Sum	Java	Note	Medium
543	Diameter of Binary Tree	Java	Note	Easy
560	Subarray Sum Equals K	Java	Note	Medium
567	Permutation in String	Java	Note	Medium
581	Shortest Unsorted Continuous Subarray	Java	Note	Easy
617	Merge Two Binary Trees	Java	Note	Easy
621	Task Scheduler	Java	Note	Medium
647	Palindromic Substrings	Java	Note	Medium
714	Best Time to Buy and Sell Stock with Transaction Fee	Java	Note	Medium
992	Subarrays with K Different Integers	Java	Note	Hard