Data Structures and Algorithms in Java

This repository is a collection of algorithms, data structures and coding challenges which I've solved over a period of time. The algorithms/solutions are implemented considering efficient Time and Space Complexity approaches. All the solutions are 100% correct and tested against various test cases, unless marked as TODO/InProgress.

This section contains implementation of different Data Structures in Java.

Data Structure	Implementation
Stack Methods Implemented: push(), pop(), peek(), isEmpty()	View
Queue Methods Implemented: offer(), poll(), peek(), isEmpty()	View
Linked List Methods Implemented: appendToTail(), add(), appendToHead(), removeFirst(), removeLast(), clone(), addAll(), reverseBetween(), getMid(), isPalindrome(), reverse(), toString(), mergeWith(), mergeTwoLists(), reverseInKGroups(), hasCycle(), removeKthFromEnd()	View
Tree Methods Implemented: preorderIterative(), inorderIterative(), levelOrder() ... many more	View
Graph Methods Implemented: BFS(), DFS(), Djikstras(), TopologicalSort()	View
Trie Methods Implemented: search(), insert(), startsWith()	View
MaxHeap Methods Implemented: insert(), fetchTop(), doubleSize()	View
MinHeap Methods Implemented: insert(), fetchTop(), doubleSize()	View
HashMap Methods Implemented: put(), add(), containsKey(), remove()	View
SegmentTree Methods Implemented: query(), update()	View
CartesianTree Methods Implemented: buildCartesianTree()	View
BinaryIndexedTree Methods Implemented: build(), query(), queryRange()	View

Algorithms Problems Java

#	Problem	Description
0	Island Perimeter	View
1	Reshape Matrix	View
2	Next Greater Element 1	View
3	Average of Levels in a Binary Tree	View
4	Judge Route Circle	View
5	Nim Game	View
6	Invert a Binary Tree	View
7	Two Sum 4 BST	View
8	Find the difference	View
9	Merge Two Binary Trees	View
10	Sum of 2 Integers	View
11	BinaryTree to String	View
12	Construct Rectangle	View
13	Distribute Candies	View
14	Convert BST to Greater Tree	View
15	Intersection of 2 Arrays	View
16	Minimum Absolute difference in BST	View
17	Ransome Note	View
18	Excelsheet Column Number	View
19	Assign Cookies	View
20	Binary Tree Tilt	View
21	Sum of left leaves	View
22	Minimum index sum of 2 lists	View
23	Majority Element	View
24	Relative Ranking	View
25	Delete Node	View
26	Contains Duplicate	View
27	Minimum moves to equal array	View
28	Longest Palindrome	View
29	Max product 3 nos	View
30	Student attendance record	View
31	Diameter of Binary Tree	View
32	Sorted array to BST	View
33	Longest Harmonic Subsequence Length	View
34	UglyNumber	View
35	Symmetric SubTree	View
36	PathSum III	View
37	Power Of 2	View
38	House Robber I	View
39	Level Order Bottomup	View
40	Set Mismatch	View
41	Intersection Arrays	View
42	LongestContinuosIncreasingSubsequence	View
43	Power 4	View
44	ReverseOfVowels	View
45	image Smoother	View
46	Perfect Square	View
47	Balanced Binary Tree	View
48	Arange Coins	View
49	Isomorphic String	View
50	Factorial Zeroes	View
51	Path Sum	View
52	Min Depth	View
53	WordPattern	View
54	Non Decreasing Array	View
55	PsychometricTesting	View
56	Sum Square Number	View
57	Length Of Last Word	View
58	Valid Palindrome II	View
59	ExcelSheetColumnTitle	View
60	PerfectNumber	View
61	FirstBadVersion	View
62	Can Place Flowers	View
63	Square Root	View
64	MaximumAverageSubarrayI	View
65	SwapNodesInPairs	View
66	Subsets I	View
67	Subsets II	View
68	Permutations	View
69	Permutations II	View
70	CombinationSum	View
71	ValidSquare	View
72	KEmptySlots	View
73	LongestAbsolutePath	View
74	LongestSubStringWithKDistinctChars	View
75	LicenseKeyFormatting	View
76	RangeSumQuery2DMutable	View
77	MovingAverage	View
78	BinaryTreeLongestConsecutiveSequence	View
79	SentenceScreenFitting	View
80	BombEnemy	View
81	ZigZagIterator	View
82	DecodeString	View
83	PalindromePairs	View
84	PowerSetSubStringsWithoutDups	View
85	PalindromicSubStrings	View
86	RepeatedStringMatch	View
87	ShortestDistanceFromAllBuildings	View
88	SkyLineProblem	View
89	MergeSortedArray	View
90	IntegerToEnglishWords	View
91	BattleShipsInABoard	View
92	LinkedListCycle	View
93	PopulatingNextRightPointersI	View
94	SearchInRotatedSortedArray	View
95	SpiralMatrixNoTouch	View
96	InorderSuccessorBST	View
97	SortColors	View
98	FindMinimumInRotatedSortedArray	View
99	AddTwoNumbersII	View
100	LowestCommonAncestorBST	View
101	ReverseWordsInStringII	View
102	MinimumPathSum	View
103	DungeonGame	View
104	SerializeAndDeserializeBinaryTree	View
105	MissingRanges	View
106	LongestConsecutiveSequence	View
107	ValidTriangleNumber	View
108	ContainerWithMostWater	View
109	BulbSwitcherI	View
110	SplitArrayWithEqualSum	View
111	FindTheCeleberity	View
112	CompareVersion	View
113	SummaryRanges	View
114	ThreeSumSmaller	View
115	UTF_8Validation	View
116	ValidAbbrevation	View
117	StrobographicNumberII	View
118	BSTIterator	View
119	MergeIntervals	View
120	FlattenNestedListIterator	View
121	EncodeAndDecodeStrings	View
122	QueueReconstructionByHeight.java	View
123	LongestSubstringWithAtMost2DistinctChars	View
124	ConstructBinaryTreeFromInorderAndPostOrderTraversal	View
125	ConstructBinaryTreeFromInorderAndPreOrderTraversal	View
126	RangeAddition	View
127	ClimbStairs	View
128	SimplifyPath	View
129	StrobogrammaticNumber	View
130	WiggleSort	View
131	BinaryTreeVerticalOrderTraversal	View
132	TrapRainWater	View
133	NthDigit	View
134	MaximumProductSubarray	View
135	IsSubSequence	View
136	RangeSumQueryImmutable	View
137	PaintHouse	View
138	EditDistance	View
139	LargestRectangleInHistogram	View
140	ShortestUnsortedContinuousSubarray	View
141	MaximalRectangle	View
142	PerfectSquares	View
143	DoubeCheckedSynchronizationSingleton	View
144	BurstBalloons	View
145	CoinChange	View
146	DecodeWays	View
147	BestTimeToBuyAndSellStock	View
148	BestTimeToBuyAndSellStockWithCooldown	View
149	UglyNumberII	View
150	IntegerBreak	View
151	WildCardMatching	View
152	DistinctSubsequence	View
153	InterleavingString	View
154	WordSearch	View
155	SudokuSolver	View
156	NQueens	View
157	NQueensII	View
158	Combinations	View
159	RestoreIpAddresses	View
160	LongestIncreasingPathInMatrix	View
161	JumpGame	View
162	SearchForRange	View
163	PeekingIterator	View
164	LongestWordInDictionaryViaDeleting	View
165	GCD	View
166	ExtendedEuclideanAlgorithm	View
167	WaterJugProblem	View
168	NextPermutation	View
169	MaximumVacationDays	View
170	LongestIncreasingSubSequence	View
171	PaintFence	View
172	LongestCommonSubsequence	View
173	MinimumInsertionForPalindrome	View
174	PowerOfThree	View
175	SubstringWithConcatenationOfWords	View
176	CombinationSumII	View
177	StringCompression	View
178	SegmentTree_RangeSum	View
179	SegmentTree_RangeMin	View
180	CountSmallerNumberAfterSelf	View
181	RangeSumQuery	View
182	MaximumBinaryTree	View
183	LargestBSTSubtree	View
184	HouseRobberII	View
185	TwoKeysKeyboard	View
186	MovieRating	View
187	ContigousSubarraysWithZeroSum	View
188	KStringSizeWith1CharRepeating2ce	View
189	FindSegementSize	View
190	UniqueBinarySearchTrees	View
191	UniqueBinarySearchTreesII	View
192	RussianDollEnvelopes	View
193	MedianTwoSortedArrays	View
194	LonelyPixelI	View
195	LonelyPixelII	View
196	KDiffPairsArray	View
197	TwoSumII	View
198	MultiplyStrings	View
199	PlusOne	View
200	ReverseBits	View
201	DetectCapital	View
202	FindLargestValueEachTreeRow	View
203	HappyNumber	View
204	AddBinary	View
205	MoveZeroes	View
206	PalindromeNumbers	View
207	NumberToBase	View
208	StrStr	View
209	LeastFrequentlyUsedCache	View
210	LeastRecentlyUsedCache	View
211	FirstUniqueCharacter	View
212	ZigZagConversion	View
213	FirstMissingPositive	View
214	FindDuplicateNumber	View
215	ProductArrayExceptSelf	View
216	LongestPalindromicSubstring	View
217	ReverseInteger	View
218	StringToInteger	View
219	ValidParanthesis	View
220	SurroundedRegions	View
221	CountingBits	View
222	FindDisappearedNumber	View
223	ThreeSum	View
224	LetterCombinationsOfPhoneNumber	View
225	GroupAnagrams	View
226	ValidAnagram	View
227	PascalsTriangleII	View
228	ThirdMaximumNumber	View
229	RegularExpressionMatching	View
230	SortByFrequency	View
231	LongestSubstringWithAtleastKRepeatingChars	View
232	GrayCode	View
233	RotateFunction	View
234	RepeatedSubstringPattern	View
235	NumberOfIslands	View
236	LongestPalindromicSubsequence	View
237	WordBreak	View
238	WordLadder	View
239	WordLadderII	View
240	WordBreakII	View
241	JewelsAndStones	View
242	UniqueEmailAddresses	View
243	FindAnagramMappings	View
244	FlippingAnImage	View
245	PeakIndexInAMountainArray	View
246	RecentCounter	View
247	DeleteColumnsToMakeSorted	View
248	LoggerRateLimiter	View
249	LeafSimilarTrees	View
250	BinaryTreeLevelOrderConstantSpace	View
251	MinimumAreaRectangle	View
252	MinimumAreaRectangleII	View
253	PatchingArray	View
254	QuickFind	View
255	QuickUnion	View
256	NRepeatedElementInSize2NArray	View
257	RangeMinimumQuery	View
258	ReversePairs	View
259	BinarySearch	View
260	FindSmallestLetterGreaterThanTarget	View
261	ClosestBinarySearchTreeValue	View
262	Heaters	View
263	SearchInASortedArrayOfUnknownSize	View
264	SearchInsertPosition	View
265	TwoSum	View
266	MaxIncreaseToKeepCitySkyline	View
267	ContinuousSubarraySum	View
268	LemonadeChange	View
269	StringWithoutAAAOrBBB	View
270	MinimumAddToMakeParenthesesValid	View
271	ScoreAfterFlippingMatrix	View
272	PartitionLabels	View
273	PalindromePartitioning	View
274	CombinationSumIII	View
275	MinimumNumberOfRefuelingStops	View
276	PalindromePartitioningII	View
277	PalindromePermutation	View
278	PalindromePermutationII	View
279	KClosestPointsToOrigin	View
280	BoyerMoore	View
281	ConvertBinarySearchTreeToSortedDoublyLinkedList	View
282	BeautifulArray	View
283	LinkedListRandomNode	View
284	RandomPickIndex	View
285	SurfaceAreaOf3DShapes	View
286	FlipGameII	View
287	MaximumDepthOfNaryTree	View
288	NaryTreeLevelOrderTraversal	View
289	EmployeeImportance	View
290	CousinsInBinaryTree	View
291	IncreasingOrderSearchTree	View
292	DistributeCoinsInBinaryTree	View
293	KeysAndRooms	View
294	NumberOfConnectedComponentsInAnUndirectedGraph	View
295	CloneGraph	View
296	WeightedQuickUnionPathCompression	View
297	RedundantConnection	View
298	MinimumDistanceBetweenBSTNodes	View
299	RangeSumOfBST	View
300	SplitBST	View
301	MyCalendarI	View
302	ImplementRand10UsingRand7	View
303	HandOfStraights	View
304	CourseSchedule	View
305	CourseScheduleII	View
306	CoinChangeII	View
307	MinimumSizeSubarraySum	View
308	RemoveKDigits	View
309	Find132pattern	View
310	EvaluateReversePolishNotation	View
311	AsteroidCollision	View
312	VerifyPreorderSequenceInBinarySearchTree	View
313	AllNodesDistanceKInBinaryTree	View
314	PopulatingNextRightPointersInEachNodeII	View
315	FindKthSmallestPairDistance	View
316	NumberOfMatchingSubsequences	View
317	ShortestWayToFormString	View
318	TopologicalSort	View
319	VerifyingAnAlienDictionary	View
320	AlienDictionary	View
321	ConstructBinaryTreeFromPreorderAndPostorderTraversal	View
322	WiggleSortII	View
323	VerticalOrderTraversalOfABinaryTree	View
324	JumpGameII	View
325	ShortestPalindrome	View
326	GraphMColoringProblem	View
327	PossibleBipartition	View
328	UniquePaths	View
329	MinimumSpanningTreeKruskals	View
330	TheEarliestMomentWhenEveryoneBecomeFriends	View
331	MaximumSubarray	View
332	PopulatingNextRightPointersInEachNode	View
333	NetworkDelayTime	View
334	CheapestFlightsWithinKStops	View
335	InsertIntoACyclicSortedList	View
336	DeleteNodesAndReturnForest	View
337	GenerateParentheses	View
338	CatalanNumber	View
339	ReconstructItinerary(EulerTour)	View
340	GameOfLife	View
341	KnightProbabilityInChessboard	View
342	MinimumHeightTrees	View
343	BinaryTreeColoringGame	View
344	SnapShotArray	View
345	CampusBikes	View
346	CampusBikesII	View
347	DailyTemperatures	View
348	GuessNumberHigherOrLowerII	View
349	SentenceSimilarityII	View
350	CarFleet	View
351	SortList	View
352	ShortestPathInBinaryMatrix	View
353	ClosestLeafInABinaryTree	View
354	CountCompleteTreeNodes	View
355	FourSum,KSum	View
356	DesignSnakeGame	View
357	RepeatedDNASequences	View
358	MostStonesRemovedWithSameRowOrColumn	View
359	SubarraySumEqualsK	View
360	SingleElementInASortedArray	View
361	PartitionEqualSubsetSum	View
362	PartitionToKEqualSumSubsets	View
363	BraceExpansion	View
364	StreamOfCharacters	View
365	ToeplitzMatrix	View
366	BullsAndCows	View
367	EvaluateDivision	View
368	BinaryStringWithSubstringsRepresenting1ToN	View
369	FillingBookcaseShelves	View
370	SortAPartiallySortedArray	View
371	LargestValuesFromLabels	View
372	HighFive	View
373	MergeSort	View
374	DifferentWaysToAddParentheses	View
375	QuickSort	View
376	UniquePathsII	View
377	MeetingRooms	View
378	MeetingRoomsII	View
379	TopKFrequentElements	View
380	GasStation	View
381	MyCalendarII	View
382	AddTwoNumbers	View
383	MergeTwoSortedLists	View
384	MergeKSortedLists	View
385	CopyListWithRandomPointer	View
386	SpiralMatrix	View
387	ReverseNodesInKGroup	View
388	TaskScheduler	View
389	DivideTwoIntegers	View
390	ConstructBinarySearchTreeFromPreorderTraversal	View
391	LowestCommonAncestorOfDeepestLeaves	View
392	IntervalListIntersections	View
393	MaximumDifferenceBetweenNodeAndAncestor	View
394	ShuffleAnArray	View
395	QuadTree	View
396	MaximumSubarrayMinProduct	View
397	FinalPricesWithASpecialDiscountInAShop	View
398	BuildingsWithOceanView	View
399	SetMatrixZeros	View
400	LowestCommonAncestorOfBinaryTreeII	View
401	FindNearestPointThatHasSameXYCoordinate	View
402	BuddyStrings	View
402	MaxAreaOfIsland	View
403	MaxConsecutiveOnesIII	View

Misc

DP 0: reduce the problem to finite state machine 1: reduce the fsm to graph 2: reduce graph to logical graph 3: traverse this graph with keeping constraints

System Design

#	Source	Description
0	Grokking	View

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