Solutions for LeetCode problems Solutions for LeetCode problems

#	Difficulty	Problem	Solution
1	Easy	Two Sum	TwoSum.java (Tests)
2	Medium	Add Two Numbers	AddTwoNumbers.java (Tests)
3	Medium	Longest Substring Without Repeating Characters	LongestSubstringWithoutRepeatingCharacters.java (Tests)
4	Hard	Median of Two Sorted Arrays	MedianOfTwoSortedArrays.java (Tests)
5	Medium	Longest Palindromic Substring	LongestPalindromicSubstring.java (Tests)
7	Easy	Reverse Integer	ReverseInteger.java (Tests)
8	Medium	String to Integer (atoi)	StringToIntegerAtoi.java (Tests)
11	Medium	Container With Most Water	ContainerWithMostWater.java (Tests)
12	Medium	Integer to Roman	IntegerToRoman.java (Tests)
13	Easy	Roman to Integer	RomanToInteger.java (Tests)
14	Easy	Longest Common Prefix	LongestCommonPrefix.java (Tests)
15	Medium	3Sum	ThreeSum.java (Tests)
17	Medium	Letter Combinations of a Phone Number	LettersOfPhoneNumber.java (Tests)
20	Easy	Valid Parentheses	ValidParentheses.java (Tests)
21	Easy	Merge Two Sorted Lists	MergeTwoSortedLists.java (Tests)
22	Medium	Generate Parentheses	GenerateParentheses.java (Tests)
23	Hard	Merge k Sorted Lists	MergeKSortedLists.java (Tests)
26	Easy	Remove Duplicates from Sorted Array	RemoveDuplicatesFromSortedArray.java (Tests)
28	Easy	Implement strStr()	ImplementStrStr.java (Tests)
29	Medium	Divide Two Integers	DivideTwoIntegers.java (Tests)
31	Medium	Next Permutation	NextPermutation.java (Tests)
33	Medium	Search in Rotated Sorted Array	SearchInRotatedSortedArray.java (Tests)
34	Medium	Find First and Last Position of Element in Sorted Array	FindFirstAndLastPositionOfElementInSortedArray.java (Tests)
37	Hard	Sudoku Solver	SudokuSolver.java (Tests)
38	Easy	Count and Say	CountAndSay.java (Tests)
42	Hard	Trapping Rain Water	TrappingRainWater.java (Tests)
48	Medium	Rotate Image	RotateImage.java (Tests)
49	Medium	Group Anagrams	GroupAnagrams.java (Tests)
50	Medium	Pow(x, n)	PowxN.java (Tests)
53	Easy	Maximum Subarray	MaximumSubarray.java (Tests)
56	Medium	Merge Intervals	MergeIntervals.java (Tests)
57	Hard	Insert Interval	InsertInterval.java (Tests)
65	Hard	Valid Number	ValidNumber.java (Tests)
66	Easy	Plus One	PlusOne.java (Tests)
67	Easy	Add Binary	AddBinary.java (Tests)
69	Easy	Sqrt(x)	Sqrtx.java (Tests)
70	Easy	Climbing Stairs	ClimbingStairs.java (Tests)
71	Medium	Simplify Path	SimplifyPath.java (Tests)
72	Hard	Edit Distance	EditDistance.java (Tests)
73	Medium	Set Matrix Zeroes	SetMatrixZeroes.java (Tests)
76	Hard	Minimum Window Substring	MinimumWindowSubstring.java (Tests)
78	Medium	Subsets	Subsets.java (Tests)
79	Medium	Word Search	WordSearch.java (Tests)
81	Medium	Search in Rotated Sorted Array II	SearchInRotatedSortedArray2.java (Tests)
84	Hard	Largest Rectangle in Histogram	LargestRectangleInHistogram.java (Tests)
85	Hard	Maximal Rectangle	MaximalRectangle.java (Tests)
88	Easy	Merge Sorted Array	MergeSortedArray.java (Tests)
89	Medium	Gray Code	GrayCode.java (Tests)
101	Easy	Symmetric Tree	SymmetricTree.java (Tests)
102	Medium	Binary Tree Level Order Traversal	BinaryTreeLevelOrderTraversal.java (Tests)
103	Medium	Binary Tree Zigzag Level Order Traversal	BinaryTreeZigzagTraversal.java (Tests)
104	Easy	Maximum Depth of Binary Tree	MaximumDepthOfBinaryTree.java (Tests)
108	Easy	Convert Sorted Array to Binary Search Tree	ConvertSortedArrayToBinarySearchTree.java (Tests)
118	Easy	Pascal's Triangle	PascalTriangle.java (Tests)
119	Easy	Pascal's Triangle II	PascalTriangle2.java (Tests)
121	Easy	Best Time to Buy and Sell Stock	BestTimeBuySellStock.java (Tests)
122	Easy	Best Time to Buy and Sell Stock II	BestTimeBuySellStock2.java (Tests)
123	Hard	Best Time to Buy and Sell Stock III	BestTimeBuySellStock3.java (Tests)
124	Hard	Binary Tree Maximum Path Sum	BinaryTreeMaximumPathSum.java (Tests)
125	Easy	Valid Palindrome	ValidPalindrome.java (Tests)
126	Hard	Word Ladder II	WordLadder2.java (Tests)
127	Medium	Word Ladder	WordLadder.java (Tests)
130	Medium	Surrounded Regions	SurroundedRegions.java (Tests)
133	Medium	Clone Graph	CloneGraph.java (Tests)
136	Easy	Single Number	SingleNumber.java (Tests)
138	Medium	Copy List with Random Pointer	CopyListWithRandomPointer.java (Tests)
139	Medium	Word Break	WordBreak.java (Tests)
140	Hard	Word Break II	WordBreak2.java (Tests)
141	Easy	Linked List Cycle	LinkedListCycle.java (Tests)
146	Medium	LRU Cache	LRUCache.java (Tests)
152	Medium	Maximum Product Subarray	MaximumProductSubarray.java (Tests)
155	Easy	Min Stack	MinStack.java (Tests)
157	Easy	Read N Characters Given Read4	ReadNCharactersGivenRead4.java (Tests)
158	Hard	Read N Characters Given Read4 II - Call multiple times	ReadNCharactersGivenRead42.java (Tests)
160	Easy	Intersection of Two Linked Lists	IntersectionOfTwoLinkedLists.java (Tests)
165	Medium	Compare Version Numbers	CompareVersionNumbers.java (Tests)
166	Medium	Fraction to Recurring Decimal	FractionToRecurringDecimal.java (Tests)
167	Easy	Two Sum II - Input array is sorted	TwoSum2InputArrayIsSorted.java (Tests)
169	Easy	Majority Element	MajorityElement.java (Tests)
171	Easy	Excel Sheet Column Number	ExcelSheetColumnNumber.java (Tests)
173	Medium	Binary Search Tree Iterator	BinarySearchTreeIterator.java (Tests)
184	Medium	Department Highest Salary	DepartmentHighestSalary.sql
188	Hard	Best Time to Buy and Sell Stock IV	BestTimeBuySellStock4.java (Tests)
189	Easy	Rotate Array	RotateArray.java (Tests)
190	Easy	Reverse Bits	ReverseBits.java (Tests)
198	Easy	House Robber	HouseRobber.java (Tests)
199	Medium	Binary Tree Right Side View	BinaryTreeRightSideView.java (Tests)
200	Medium	Number of Islands	NumberOfIslands.java (Tests)
202	Easy	Happy Number	HappyNumber.java (Tests)
204	Easy	Count Primes	CountPrimes.java (Tests)
206	Easy	Reverse Linked List	ReverseLinkedList.java (Tests)
207	Medium	Course Schedule	CourseSchedule.java (Tests)
211	Medium	Add and Search Word - Data structure design	AddAndSearchWordDataStructureDesign.java (Tests)
212	Hard	Word Search II	WordSearch2.java (Tests)
215	Medium	Kth Largest Element in an Array	KthLargestElementInArray.java (Tests)
217	Easy	Contains Duplicate	ContainsDuplicate.java (Tests)
221	Medium	Maximal Square	MaximalSquare.java (Tests)
224	Hard	Basic Calculator	BasicCalculator.java (Tests)
227	Medium	Basic Calculator II	BasicCalculator2.java (Tests)
230	Medium	Kth Smallest Element in a BST	KthSmallestElementInBST.java (Tests)
234	Easy	Palindrome Linked List	PalindromeLinkedList.java (Tests)
235	Easy	Lowest Common Ancestor of a Binary Search Tree	LowestCommonAncestorOfBST.java (Tests)
236	Medium	Lowest Common Ancestor of a Binary Tree	LowestCommonAncestorOfBT.java (Tests)
237	Easy	Delete Node in a Linked List	DeleteNodeInALinkedList.java (Tests)
238	Medium	Product of Array Except Self	ProductOfArrayExceptSelf.java (Tests)
239	Hard	Sliding Window Maximum	SlidingWindowMaximum.java (Tests)
240	Medium	Search a 2D Matrix II	Search2dMatrix2.java (Tests)
242	Easy	Valid Anagram	ValidAnagram.java (Tests)
249	Medium	Group Shifted Strings	GroupShiftedStrings.java (Tests)
252	Easy	Meeting Rooms	MeetingRooms.java (Tests)
253	Medium	Meeting Rooms II	MeetingRooms2.java (Tests)
257	Easy	Binary Tree Paths	BinaryTreePaths.java (Tests)
266	Easy	Palindrome Permutation	PalindromePermutation.java (Tests)
268	Easy	Missing Number	MissingNumber.java (Tests)
269	Hard	Alien Dictionary	AlienDictionary.java (Tests)
270	Easy	Closest Binary Search Tree Value	ClosestBinarySearchTreeValue.java (Tests)
273	Hard	Integer to English Words	IntegerToEnglishWords.java (Tests)
278	Easy	First Bad Version	FirstBadVersion.java (Tests)
282	Hard	Expression Add Operators	ExpressionAddOperators.java (Tests)
283	Easy	Move Zeroes	MoveZeroes.java (Tests)
295	Hard	Find Median from Data Stream	MedianFinder.java (Tests)
297	Hard	Serialize and Deserialize Binary Tree	SerializeAndDeserializeBT.java (Tests)
299	Easy	Bulls and Cows	BullsAndCows.java (Tests)
301	Hard	Remove Invalid Parentheses	RemoveInvalidParentheses.java (Tests)
311	Medium	Sparse Matrix Multiplication	SparseMatrixMultiplication.java (Tests)
314	Medium	Binary Tree Vertical Order Traversal	BinaryTreeVerticalOrderTraversal.java (Tests)
315	Hard	Count Of Smaller Numbers After Self	CountOfSmallerNumbersAfterSelf.java (Tests)
322	Medium	Coin Change	CoinChange.java (Tests)
323	Medium	Number of Connected Components in an Undirected Graph	NumberOfConnectedComponentsInGraph.java (Tests)
329	Hard	Longest Increasing Path in a Matrix	LongestIncreasingPathInAMatrix.java (Tests)
339	Easy	Nested List Weight Sum	NestedListWeightSum.java (Tests)
340	Hard	Longest Substring with At Most K Distinct Characters	LongestSubstringWithAtMostKDistinctCharacters.java (Tests)
344	Easy	Reverse String	ReverseString.java (Tests)
346	Easy	Moving Average from Data Stream	MovingAverageFromDataStream.java (Tests)
347	Medium	Top K Frequent Elements	TopKFrequentElements.java (Tests)
348	Medium	Design Tic-Tac-Toe	TicTacToe.java (Tests)
350	Easy	Intersection of Two Arrays II	IntersectionOfTwoArrays2.java (Tests)
359	Easy	Logger Rate Limiter	LoggerRateLimiter.java (Tests)
362	Medium	Design Hit Counter	HitCounter.java (Tests)
371	Easy	Sum of Two Integers	SumOfTwoIntegers.java (Tests)
380	Medium	Insert Delete GetRandom O(1)	InsertDeleteGetRandomO1.java (Tests)
387	Easy	First Unique Character in a String	FirstUniqueCharacterInString.java (Tests)
394	Medium	Decode String	DecodeString.java (Tests)
398	Medium	Random Pick Index	RandomPickIndex.java (Tests)
405	Easy	Convert a Number to Hexadecimal	ConvertANumberToHexadecimal.java (Tests)
412	Easy	Fizz Buzz	FizzBuzz.java (Tests)
415	Easy	Add Strings	AddStrings.java (Tests)
416	Medium	Partition Equal Subset Sum	PartitionEqualSubsetSum.java (Tests)
438	Medium	Find All Anagrams in a String	FindAllAnagramsInAString.java (Tests)
443	Easy	String Compression	StringCompression.java (Tests)
449	Medium	Serialize and Deserialize BST	SerializeAndDeserializeBST.java (Tests)
485	Easy	Max Consecutive Ones	MaxConsecutiveOnes.java (Tests)
487	Medium	Max Consecutive Ones II	MaxConsecutiveOnes2.java (Tests)
489	Hard	Robot Room Cleaner	RobotRoomCleaner.java (Tests)
518	Medium	Coin Change 2	CoinChange2.java (Tests)
523	Medium	Continuous Subarray Sum	ContinuousSubarraySum.java (Tests)
528	Medium	Random Pick with Weight	RandomPickWithWeight.java (Tests)
535	Medium	Encode and Decode TinyURL	EncodeAndDecodeTinyURL.java (Tests)
538	Easy	Convert BST to Greater Tree	ConvertBSTtoGreaterTree.java (Tests)
543	Easy	Diameter of Binary Tree	DiameterOfBinaryTree.java (Tests)
560	Medium	Subarray Sum Equals K	SubarraySumEqualsK.java (Tests)
562	Medium	Longest Line of Consecutive One in Matrix	LongestLineOfConsecutiveOneInMatrix.java (Tests)
617	Easy	Merge Two Binary Trees	MergeTwoBinaryTrees.java (Tests)
621	Medium	Task Scheduler	TaskScheduler.java (Tests)
636	Medium	Exclusive Time of Functions	ExclusiveTimeOfFunctions.java (Tests)
652	Medium	Find Duplicate Subtrees	FindDuplicateSubtrees.java (Tests)
659	Medium	Split Array into Consecutive Subsequences	SplitArrayIntoConsecutiveSubsequences.java (Tests)
670	Medium	Maximum Swap	MaximumSwap.java (Tests)
680	Easy	Valid Palindrome II	ValidPalindrome2.java (Tests)
689	Hard	Maximum Sum of 3 Non-Overlapping Subarrays	MaximumSumOf3NonOverlappingSubarrays.java (Tests)
690	Easy	Employee Importance	EmployeeImportance.java (Tests)
692	Medium	Top K Frequent Words	TopKFrequentWords.java (Tests)
721	Medium	Accounts Merge	AccountsMerge.java (Tests)
729	Medium	My Calendar I	MyCalendar.java (Tests)
733	Easy	Flood Fill	FloodFill.java (Tests)
746	Easy	Min Cost Climbing Stairs	MinCostClimbingStairs.java (Tests)
752	Medium	Open the Lock	OpenTheLock.java (Tests)
763	Medium	Partition Labels	PartitionLabels.java (Tests)
767	Medium	Reorganize String	ReorganizeString.java (Tests)
771	Easy	Jewels and Stones	JewelsAndStones.java (Tests)
772	Hard	Basic Calculator III	BasicCalculator3.java (Tests)
785	Medium	Is Graph Bipartite?	IsGraphBipartite.java (Tests)
791	Medium	Custom Sort String	CustomSortString.java (Tests)
809	Medium	Expressive Words	ExpressiveWords.java (Tests)
819	Easy	Most Common Word	MostCommonWord.java (Tests)
833	Medium	Find And Replace in String	FindAndReplaceInString.java (Tests)
840	Easy	Magic Squares In Grid	MagicSquaresInGrid.java (Tests)
843	Hard	Guess the Word	GuessTheWord.java (Tests)
844	Easy	Backspace String Compare	BackspaceStringCompare.java (Tests)
846	Medium	Hand of Straights	HandOfStraights.java (Tests)
865	Medium	Smallest Subtree With all the Deepest Nodes	SmallestSubtreeWithAllTheDeepestNodes.java (Tests)
896	Easy	Monotonic Array	MonotonicArray.java (Tests)
900	Medium	RLE Iterator	RLEIterator.java (Tests)
914	Easy	X of a Kind in a Deck of Cards	XOfAKindInADeckOfCards.java (Tests)
934	Medium	Shortest Bridge	ShortestBridge.java (Tests)
937	Easy	Reorder Log Files	ReorderLogFiles.java (Tests)
938	Easy	Range Sum of BST	RangeSumOfBst.java (Tests)
946	Medium	Validate Stack Sequences	ValidateStackSequences.java (Tests)
951	Medium	Flip Equivalent Binary Trees	FlipEquivalentBinaryTrees.java (Tests)
953	Easy	Verifying an Alien Dictionary	VerifyingAnAlienDictionary.java (Tests)
973	Medium	K Closest Points to Origin	KClosestPointsToOrigin.java (Tests)
986	Medium	Interval List Intersections	IntervalListIntersections.java (Tests)
987	Medium	Vertical Order Traversal of a Binary Tree	VerticalOrderTraversalOfABinaryTree.java (Tests)
1004	Medium	Max Consecutive Ones III	MaxConsecutiveOnes3.java (Tests)
1014	Medium	Best Sightseeing Pair	BestSightseeingPair.java (Tests)
1026	Medium	Maximum Difference Between Node and Ancestor	MaximumDifferenceBetweenNodeAndAncestor.java (Tests)
1031	Medium	Maximum Sum of Two Non-Overlapping Subarrays	MaximumSumOfTwoNonOverlappingSubarrays.java (Tests)
1048	Medium	Longest String Chain	LongestStringChain.java (Tests)
1060	Medium	Missing Element in Sorted Array	MissingElementInSortedArray.java (Tests)
1094	Medium	Car Pooling	CarPooling.java (Tests)
1110	Medium	Delete Nodes And Return Forest	DeleteNodesAndReturnForest.java (Tests)
1138	Medium	Alphabet Board Path	AlphabetBoardPath.java (Tests)
1140	Medium	Stone Game II	StoneGame2.java (Tests)
1189	Easy	Maximum Number of Balloons	MaximumNumberOfBalloons.java (Tests)
1193	Medium	Monthly Transactions I	MonthlyTransactions.sql
1197	Medium	Minimum Knight Moves	MinimumKnightMoves.java (Tests)
1231	Hard	Divide Chocolate	DivideChocolate.java (Tests)
1249	Medium	Minimum Remove to Make Valid Parentheses	MinimumRemoveToMakeValidParentheses.java (Tests)
1296	Medium	Divide Array in Sets of K Consecutive Numbers	DivideArrayInSetsOfKConsecutiveNumbers.java (Tests)
1376	Medium	Time Needed to Inform All Employees	TimeNeededToInformAllEmployees.java (Tests)
1423	Medium	Maximum Points You Can Obtain from Cards	MaximumPointsYouCanObtainFromCards.java (Tests)
1428	Medium	Leftmost Column with at Least a One	LeftmostColumnWithAtLeastAOne.java (Tests)
1438	Medium	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	LongestContinuousSubarrayWithDiffUpToLimit.java (Tests)
1463	Hard	Cherry Pickup II	CherryPickup2.java (Tests)
1504	Medium	Count Submatrices With All Ones	CountSubmatricesWithAllOnes.java (Tests)