This repository contains HackerRank problems solutions

• 30 DAYS OF CODE

• JAVA

• ALGORITHMS

• CRACKING THE CODING INTERVIEW

• DATA STRUCTURES

• GENERAL PROGRAMMING

• IMPLEMENTATION

  Coding environment used- Windows 8.1, Eclipse Oxygen, JAVA 8

30 DAYS OF CODE

Day	Challenge	Solution
0	Hello, World	Day0HelloWorld.java
1	Data Types	Day1DataTypes.java
2	Operators	Day2Operators.java
3	Intro to Conditional Statements	Day3IntroToConditionalStatements.java
4	Class vs. Instance	Day4ClassVsInstance.java
5	Loops	Day5Loops.java
6	Let's Review	Day6LetsReview.java
7	Arrays	Day7Arrays.java
8	Dictionaries and Maps	Day8DictionariesAndMaps.java
9	Recursion	Day9Recursion.java
10	Binary Numbers	Day10BinaryNumbers.java
11	2D Arrays	Day112DArrays.java
12	Inheritance	Student.java
13	Abstract Classes	MyBook.java
14	Scope	Day14Scope.java
15	Linked List	Day15LinkedList.java
16	Exceptions - String to Integer	Day16ExceptionsStringToInteger.java
17	MoreExceptions	Day17MoreExceptions.java
18	QueuesAndStacks	Day18QueuesAndStacks.java
19	Interfaces	Day19Interfaces.java
20	Sorting	Day20Sorting.java
21	Generics	Day21Generics.java
22	BinarySearchTrees	Day22BinarySearchTrees.java
23	BSTLevelOrderTraversal	Day23BSTLevelOrderTraversal.java
24	MoreLinkedLists	Day24MoreLinkedLists.java
25	RunningTimeAndComplexity	Day25RunningTimeAndComplexity.java
26	Nested Logic	Day26NestedLogic.java
27	Day 27: Testing	Day27Testing.java
28	RegEx,Patterns,and Intro to Databases	Day28RegExPatternsAndIntroToDatabases.java
29	Bitwise AND	Day29BitwiseAND.java

JAVA

Subdomain	Challenge	Solution
Introduction	Welcome to Java!	WelcomeToJava.java
Introduction	Java Stdin and Stdout I	JavaStdinAndStdoutI.java
Introduction	Java If-Else	JavaIfElse.java
Introduction	Java Stdin and Stdout II	JavaStdinAndStdoutII.java
Introduction	Java Output Formatting	JavaOutputFormatting.java
Introduction	Java Loops I	JavaLoopsI.java
Introduction	Java Loops II	JavaLoopsII.java
Introduction	Java Datatypes	JavaDatatypes.java
Introduction	Java End-of-file	JavaEndOfFile.java
Introduction	Java Static Initializer Block	JavaStaticInitializerBlock.java
Introduction	Java Int to String	JavaIntToString.java
Introduction	Java Date and Time	JavaDateAndTime.java
Introduction	Java Currency Formatter	JavaCurrencyFormatter.java
Strings	Java Strings Introduction	JavaStringsIntroduction.java
Strings	Java Substring	JavaSubstring.java
Strings	Java Substring Comparisons	JavaSubstringComparisons.java
Strings	Java String Reverse	JavaStringReverse.java
Strings	Java Anagrams	JavaAnagrams.java
Strings	Java String Tokens	JavaStringTokens.java
Strings	Pattern Syntax Checker	PatternSyntaxChecker.java
Strings	Valid Username Regular Expression	ValidUsernameRegularExpression.java
Strings	Tag Content Extractor	TagContentExtractor.java
Strings	Java Regex	JavaRegex.java
Strings	Java Regex 2 - Duplicate Words	JavaRegex2DuplicateWords.java
BigInteger	Java BigInteger	JavaBigInteger.java
BigInteger	Java BigDecimal	JavaBigDecimal.java
BigInteger	Java Primality Test	JavaPrimalityTest.java
Data Structures	Java 1D Array	Java1DArray.java
Data Structures	Java 2D Array	Java2DArray.java
Data Structures	Java Subarray	JavaSubarray.java
Data Structures	Java Arraylist	JavaArraylist.java
Data Structures	Java Map	JavaMap.java
Data Structures	Java Hashset	JavaHashset.java
Data Structures	Java Comparator	JavaComparator.java
Data Structures	Java Sort	JavaSort.java
Data Structures	Java List	JavaList.java
Data Structures	Java Generics	JavaGenerics.java
Data Structures	Java Stack	JavaStack.java
Data Structures	Java Dequeue	JavaDequeue.java
Data Structures	Java BitSet	JavaBitSet.java
Data Structures	Java Priority Queue	JavaPriorityQueue.java
Data Structures	Java 1D Array (Part 2)	Java1DArrayPart2.java
Object Oriented Programming	Java Inheritance I	JavaInheritanceI.java
Object Oriented Programming	Java Inheritance II	JavaInheritanceII.java
Object Oriented Programming	Java Abstract Class	JavaAbstractClass.java
Object Oriented Programming	Java Interface	JavaInterface.java
Object Oriented Programming	Java Method Overriding	JavaMethodOverriding.java
Object Oriented Programming	Java Method Overriding 2(Super Keyword)	JavaMethodOverriding2SuperKeyword.java
Object Oriented Programming	Java Instanceof keyword	JavaInstanceofkeyword.java
Object Oriented Programming	Java Iterator	JavaIterator.java
Exception Handling	Java Exception Handling (Try-catch)	JavaExceptionHandlingTryCatch.java
Exception Handling	Java Exception Handling	JavaExceptionHandling.java
Advanced	Java Varargs - Simple Addition	JavaVarargsSimpleAddition.java
Advanced	Java Reflection - Attributes	JavaReflectionAttributes.java
Advanced	Can You Access?	CanYouAccess.java
Advanced	Java Factory Pattern	JavaFactoryPattern.java
Advanced	Java Singleton Pattern	JavaSingletonPattern.java
Advanced	Covariant Return Types	CovariantReturnTypes.java
Advanced	Prime Checker	PrimeChecker.java
Advanced	Java Annotations	JavaAnnotations.java
Advanced	Java Lambda Expressions	JavaLambdaExpressions.java
Advanced	Java MD5	JavaMD5.java
Advanced	Java SHA-256	JavaSHA256.java
Advanced	Java Visitor Pattern	JavaVisitorPattern.java

ALGORITHMS

Subdomain	Challenge	Solution
Sorting	Quicksort 1 - Partition	Quicksort1Partition.java
Sorting	Marc's Cakewalk	MarcsCakewalk.java
Sorting	Minimum Absolute Difference in an Array	MinimumAbsoluteDifferenceInAnArray.java
Sorting	Luck Balance	LuckBalance.java
Sorting	Climbing the Leaderboard	ClimbingTheLeaderboard.java
Sorting	Big Sorting	BigSorting.java
Sorting	Insertion Sort - Part 1	InsertionSortPart1.java
Sorting	Insertion Sort - Part 2	InsertionSortPart2.java
Sorting	Correctness and the Loop Invariant	CorrectnessAndTheLoopInvariant.java
Sorting	Running Time of Algorithms	RunningTimeOfAlgorithms.java
Sorting	Counting Sort 1	CountingSort1.java
Sorting	Counting Sort 2	CountingSort2.java
Sorting	Counting Sort 3	CountingSort3.java
Sorting	Intro to Tutorial Challenges	IntroToTutorialChallenges.java
Sorting	Find the Median	FindTheMedian.java
Sorting	Closest Numbers	ClosestNumbers.java
Sorting	Mark and Toys	MarkAndToys.java
Sorting	Jim and the Orders	JimAndTheOrders.java
search	Lonely Integer	LonelyInteger.java
search	Bit Manipulation: Lonely Integer	BitManipulationLonelyInteger.java
search	Ice Cream Parlor	IceCreamParlor.java
search	HashTables: IceCreamParlor	HashTablesIceCreamParlor.java
search	Minimum Loss	MinimumLoss.java
Greedy Algorithms	Marc's Cakewalk	MarcsCakewalk.java
Greedy Algorithms	Luck Balance	LuckBalance.java
Greedy Algorithms	Equal Stacks	EqualStacks.java
Greedy Algorithms	Mark and Toys	MarkAndToys.java
Greedy Algorithms	Jim and the Orders	JimAndTheOrders.java
Greedy Algorithms	Priyanka and Toys	PriyankaAndToys.java
Graph Theory	Kruskal (MST): Really Special Subtree	KruskalMSTReallySpecialSubtree.java
Graph Theory	Breadth First Search: Shortest Reach	BreadthFirstSearchShortestReach.java
Graph Theory	Prim's (MST) : Special Subtree	PrimsMSTSpecialSubtree.java
Strings	Super Reduced String	SuperReducedString.java
Strings	Caesar Cipher	CaesarCipher.java
Strings	Mars Exploration	MarsExploration.java
Strings	CamelCase	CamelCase.java
Strings	Gemstones	Gemstones.java
Strings	The Love-Letter Mystery	TheLoveLetterMystery.java
Strings	Pangrams	Pangrams.java
Strings	Alternating Characters	AlternatingCharacters.java
Strings	Beautiful Binary String	BeautifulBinaryString.java
Strings	Big Sorting	BigSorting.java
Strings	Anagram	Anagram.java
Strings	Two Strings	TwoStrings.java
Strings	Funny String	FunnyString.java
Strings	String Construction	StringConstruction.java
Strings	Strings: Making Anagrams	StringsMakingAnagrams.java
Strings	Making Anagrams	MakingAnagrams.java
Strings	Caesar Cipher: Encryption	CaesarCipherEncryption.java
Strings	Game of Thrones - I	GameOfThronesI.java
Strings	Sherlock and the Valid String	SherlockAndTheValidString.java
Dynamic Programming	Fibonacci Modified	FibonacciModified.java
Bit Manipulation	Lonely Integer	LonelyInteger.java
Bit Manipulation	Bit Manipulation: Lonely Integer	BitManipulationLonelyInteger.java
Bit Manipulation	Sum vs XOR	SumvsXOR.java
Bit Manipulation	Maximizing XOR	MaximizingXOR.java
Bit Manipulation	Sansa and XOR	SansaAndXOR.java

CRACKING THE CODING INTERVIEW

Topic	Challenge	Solution
Techniques / Concepts	Time Complexity: Primality	Primality.java
Techniques / Concepts	Recursion: Fibonacci Numbers	FibonacciNumber.java
Techniques / Concepts	Recursion: Davis' Staircase	DavisStaircase.java
Techniques / Concepts	Bit Manipulation: Lonely Integer	LonelyInteger.java
Techniques / Concepts	DP: Coin Change	DPCoinChange.java
Data Structures	Arrays: Left Rotation	LeftRotation.java
Data Structures	Strings: Making Anagrams	MakingAnagrams.java
Data Structures	Hash Tables: Ransom Note	HashTablesRansomNote.java
Data Structures	Linked Lists: Detect a Cycle	DetectACycle.java
Data Structures	Stacks: Balanced Brackets	BalancedBrackets.java
Data Structures	Trees: Is This a Binary Search Tree?	TreesIsThisABinarySearchTree.java
Data Structures	Heaps: Find the Running Median	HeapsFindTheRunningMedian.java
Data Structures	Tries: Contacts	TriesContacts.java
Algorithms	Sorting: Bubble Sort	SortingBubbleSort.java
Algorithms	Sorting: Comparator	SortingComparator.java
Algorithms	Hash Tables: Ice Cream Parlor	HashTablesIceCreamParlor.java
Algorithms	BFS: Shortest Reach in a Graph	BFSShortestReachInAGraph.java

DATA STRUCTURES

Subdomain	Challenge	Solution
Arrays	Arrays - DS	ArraysDS.java
Arrays	2D Array - DS	TwoDArrayDS.java
Arrays	Dynamic Array	DynamicArray.java
Arrays	Left Rotation	LeftRotation.java
Arrays	Big Sorting	BigSorting.java
Arrays	Sparse Arrays	SparseArrays.java
Arrays	Array Manipulation	ArrayManipulation.java
Stacks	Maximum Element	MaximumElement.java
Stacks	Balanced Brackets	BalancedBrackets.java
Stacks	Equal Stacks	EqualStacks.java
Stacks	Largest Rectangle	LargestRectangle.java
Stacks	Simple Text Editor	SimpleTextEditor.java
Trees	Preorder Traversal	PreorderTraversal.java
Trees	Inorder Traversal	InorderTraversal.java
Trees	Postorder Traversal	PostorderTraversal.java
Trees	Height of a Binary Tree	HeightOfABinaryTree.java
Trees	Level Order Traversal	LevelOrderTraversal.java
Trees	Huffman Decoding	HuffmanDecoding.java
Trees	Top View	TopView.java
Linked List	Print the Elements of a Linked List	PrintTheElementsOfALinkedList.java
Linked List	Insert a node at the head of a linked list	InsertANodeAtHeadOfAList.java
Linked List	Insert a Node at the Tail of a Linked List	InsertANodeAtTheTailOfALinkedList.java
Linked List	Insert a node at a specific position in a linked list	InsertANodeAtASpecificPositionInALinkedList.java
Linked List	Delete a Node	DeleteANode.java
Linked List	Print in Reverse	PrintInReverse.java
Linked List	Reverse a linked list	ReverseALinkedList.java
Linked List	Compare two linked lists	CompareTwoLinkedLists.java
Linked List	Merge two sorted linked lists	MergeTwoSortedLinkedLists.java
Linked List	Get Node Value	GetNodeValue.java
Linked List	Delete duplicate-value nodes from a sorted linked list	DeleteDuplicateValueNodesFromASortedLinkedList.java
Linked List	Cycle Detection	CycleDetection.java
Linked List	Find Merge Point of Two Lists	FindMergePointOfTwoLists.java
Linked List	Inserting a Node Into a Sorted Doubly Linked List	InsertingANodeIntoASortedDoublyLinkedList.java
Linked List	Reverse a doubly linked list	ReverseADoublyLinkedList.java
Tries	Contacts	Contacts.java
Tries	No Prefix Set	NoPrefixSet.java
Queues	Queue using Two Stacks	QueueUsingTwoStacks.java
Heaps	QHEAP1	QHEAP1.java
Heaps	Jesse and Cookies	JesseAndCookies.java
Heaps	Find the Running Median	FindTheRunningMedian.java
Disjoint Set	Merging Communities	MergingCommunities.java
Disjoint Set	Components in a graph	ComponentsInAGraph.java

GENERAL PROGRAMMING

Subdomain	Challenge	Solution	Video Explaination
Basic Programming	Solve Me First	SolveMeFirst.java	Tutorial
Basic Programming	Staircase	Staircase.java	Tutorial
Basic Programming	Plus Minus	PlusMinus.java	Tutorial
Basic Programming	Diagonal Difference	DiagonalDifference.java
Basic Programming	A Very Big Sum	AVeryBigSum.java	Tutorial
Basic Programming	Simple Array Sum	SimpleArraySum.java	Tutorial
Basic Programming	Compare the Triplets	CompareTheTriplets.java
Basic Programming	Divisible Sum Pairs	DivisibleSumPairs.java
Basic Programming	Kangaroo	Kangaroo.java
Basic Programming	Drawing Book	DrawingBook.java
Basic Programming	Birthday Cake Candles	BirthdayCakeCandles.java
Basic Programming	Bon Appétit	BonAppétit.java
Basic Programming	Sock Merchant	SockMerchant.java
Basic Programming	Apple and Orange	AppleAndOrange.java
Basic Programming	Between Two Sets	BetweenTwoSets.java
Basic Programming	Mini-Max Sum	MiniMaxSum.java
Basic Programming	Grading Students	GradingStudents.java
Basic Programming	Breaking the Records	BreakingTheRecords.java
Basic Programming	Migratory Birds	MigratoryBirds.java
Basic Programming	Birthday Chocolate	BirthdayChocolate.java
Basic Programming	Time Conversion	TimeConversion.java
Basic Programming	Library Fine	LibraryFine.java
Basic Programming	Save the Prisoner!	SaveThePrisoner.java
Basic Programming	Jumping on the Clouds: Revisited	JumpingOnTheCloudsRevisited.java
Basic Programming	Counting Valleys	CountingValleys.java
Basic Programming	Viral Advertising	ViralAdvertising.java
Basic Programming	Beautiful Days at the Movies	BeautifulDaysAtTheMovies.java
Basic Programming	Electronics Shop	ElectronicsShop.java
Basic Programming	Cats and a Mouse	CatsAndAMouse.java
Basic Programming	Day of the Programmer	DayOfTheProgrammer.java
Basic Programming	The Hurdle Race	TheHurdleRace.java
Basic Programming	Utopian Tree	UtopianTree.java
Basic Programming	Service Lane	ServiceLane.java
Basic Programming	Circular Array Rotation	CircularArrayRotation.java
Basic Programming	Sherlock and Squares	SherlockAndSquares.java
Basic Programming	Angry Professor	AngryProfessor.java
Basic Programming	Extra Long Factorials	ExtraLongFactorials.java
Basic Programming	Minimum Distances	MinimumDistances.java
Basic Programming	Non-Divisible Subset	NonDivisibleSubset.java
Basic Programming	Beautiful Triplets	BeautifulTriplets.java
Basic Programming	Jumping on the Clouds	JumpingOnTheClouds.java
Basic Programming	Equalize the Array	EqualizeTheArray.java
Basic Programming	Designer PDF Viewer	DesignerPDFViewer.java
Basic Programming	Forming a Magic Square	FormingAMagicSquare.java
Basic Programming	Repeated String	RepeatedString.java
Basic Programming	Bitwise AND	BitwiseAND.java
Basic Programming	Divisible Pairs Sum	DivisiblePairsSum.java
Basic Programming	Append and Delete	AppendAndDelete.java
Basic Programming	Picking Numbers	PickingNumbers.java
Basic Programming	Climbing the Leaderboard	ClimbingTheLeaderboard.java
Basic Programming	Sequence Equation	SequenceEquation.java
Basic Programming	Find Digits	FindDigits.java
Basic Programming	Chocolate Feast	ChocolateFeast.java
Basic Programming	Cut the sticks	CutTheSticks.java
Basic Programming	ACM ICPC Team	ACMICPCTeam.java
Basic Programming	Taum and B'day	TaumAndBday.java
Basic Programming	The Time in Words	TheTimeInWords.java
Basic Programming	Flatland Space Stations	FlatlandSpaceStations.java
Basic Programming	Lisa's Workbook	LisasWorkbook.java
Basic Programming	Fair Rations	FairRations.java
Basic Programming	Manasa and Stones	ManasaAndStones.java
Basic Programming	Cavity Map	CavityMap.java
Basic Programming	The Grid Search	TheGridSearch.java
Basic Programming	Happy Ladybugs	HappyLadybugs.java
Basic Programming	Strange Counter	StrangeCounter.java
Basic Programming	Consecutive 1's in Binary Numbers	Consecutive1sInBinaryNumbers.java

IMPLEMENTATION

Subdomain	Challenge	Solution
Brute Force	Day of the Programmer	DayOfTheProgrammer.java
Brute Force	Pangrams	Pangrams.java
Brute Force	Climbing the Leaderboard	ClimbingTheLeaderboard.java
Brute Force	Strings: Making Anagrams	StringsMakingAnagrams.java
Brute Force	Encryption	Encryption.java
Brute Force	Making Anagrams	MakingAnagrams.java