HackerRank

Solutions to HackerRank problems

• Algorithms
• Data Structures
• Python
• Linux Shell
• CPP
• C
• Interview Preparation Kit

Algorithms

Subdomain	Difficulty	Challenge	Solution
Warmup	Easy	Solve Me First	solve-me-first.py
Warmup	Easy	Simple Array Sum	simple-array-sum.py
Warmup	Easy	Compare the Triplets	compare-the-triplets.py
Warmup	Easy	A Very Big Sum	a-very-big-sum.py
Warmup	Easy	Diagonal Difference	diagonal-difference.py
Warmup	Easy	Plus Minus	plus-minus.py
Warmup	Easy	Staircase	staircase.py
Warmup	Easy	Mini-Max Sum	mini-max-sum.py
Warmup	Easy	Birthday Cake Candles	birthday-cake-candles.py
Warmup	Easy	Time Conversion	time-conversion.py
Implementation	Easy	Grading Students	grading.py
Implementation	Easy	Apple and Orange	apple-and-orange.py
Implementation	Easy	Kangaroo	kangaroo.py
Implementation	Easy	Between Two Sets	between-two-sets.py
Implementation	Easy	Breaking the Records	breaking-best-and-worst-records.py
Implementation	Easy	Birthday Chocolate	the-birthday-bar.py
Implementation	Easy	Divisible Sum Pairs	divisible-sum-pairs.py
Implementation	Easy	Migratory Birds	migratory-birds.py
Implementation	Easy	Day of the Programmer	day-of-the-programmer.py
Implementation	Easy	Bon Appétit	bon-appetit.py
Implementation	Easy	Sock Merchant	sock-merchant.py
Implementation	Easy	Drawing Book	drawing-book.py
Implementation	Easy	Counting Valleys	counting-valleys.py
Implementation	Easy	Electronics Shop	electronics-shop.py
Implementation	Easy	Cats and a Mouse	cats-and-a-mouse.py
Implementation	Easy	Picking Numbers	picking-numbers.py
Implementation	Easy	The Hurdle Race	the-hurdle-race.py
Implementation	Easy	Designer PDF Viewer	designer-pdf-viewer.py
Implementation	Easy	Utopian Tree	utopian-tree.py
Implementation	Easy	Angry Professor	angry-professor.py
Implementation	Easy	Beautiful Days at the Movies	beautiful-days-at-the-movies.py
Implementation	Easy	Viral Advertising	strange-advertising.py
Implementation	Easy	Save the Prisoner!	save-the-prisoner.py
Implementation	Easy	Circular Array Rotation	circular-array-rotation.py
Implementation	Easy	Sequence Equation	permutation-equation.py
Implementation	Easy	Jumping on the Clouds: Revisited	jumping-on-the-clouds-revisited.py
Implementation	Easy	Find Digits	find-digits.py
Implementation	Easy	Append and Delete	append-and-delete.py
Implementation	Easy	Sherlock and Squares	sherlock-and-squares.py
Implementation	Easy	Library Fine	library-fine.py
Implementation	Easy	Cut the sticks	cut-the-sticks.py
Implementation	Easy	Repeated String	repeated-string.py
Implementation	Easy	Jumping on the Clouds	jumping-on-the-clouds.py
Implementation	Easy	Equalize the Array	equality-in-a-array.py
Implementation	Easy	ACM ICPC Team	acm-icpc-team.py
Implementation	Easy	Taum and B'day	taum-and-bday.py
Implementation	Easy	Modified Kaprekar Numbers	kaprekar-numbers.py
Implementation	Easy	Beautiful Triplets	beautiful-triplets.py
Implementation	Easy	Minimum Distances	minimum-distances.py
Implementation	Easy	Chocolate Feast	chocolate-feast.py
Implementation	Easy	Service Lane	service-lane.py
Implementation	Easy	Lisa's Workbook	lisa-workbook.py
Implementation	Easy	Flatland Space Stations	flatland-space-stations.py
Implementation	Easy	Fair Rations	fair-rations.py
Implementation	Easy	Cavity Map	cavity-map.py
Implementation	Easy	Manasa and Stones	manasa-and-stones.py
Implementation	Easy	Happy Ladybugs	happy-ladybugs.py
Implementation	Easy	Strange Counter	strange-code.py
Implementation	Easy	Halloween Sale	halloween-sale.py
Implementation	Medium	Forming a Magic Square	magic-square-forming.py
Implementation	Medium	Climbing the Leaderboard	climbing-the-leaderboard.py
Implementation	Medium	Extra Long Factorials	extra-long-factorials.py
Implementation	Medium	Non-Divisible Subset	non-divisible-subset.py
Implementation	Medium	Queen's Attack II	queens-attack-2.py
Implementation	Medium	Encryption	encryption.py
Implementation	Medium	Bigger is Greater	bigger-is-greater.py
Implementation	Medium	The Time in Words	the-time-in-words.py
Implementation	Medium	The Grid Search	the-grid-search.py
Implementation	Medium	3D Surface Area	3d-surface-area.py
Implementation	Medium	Absolute Permutation	absolute-permutation.py
Implementation	Medium	Ema's Supercomputer	two-pluses.py
Implementation	Medium	Larry's Array	larrys-array.py
Implementation	Medium	Almost Sorted	almost-sorted.py
Sorting	Easy	Big Sorting	big-sorting.py
Strings	Easy	Super Reduced String	reduced-string.py
Strings	Easy	CamelCase	camelcase.py
Strings	Easy	Two Characters	two-characters.py
Strings	Easy	Caesar Cipher	caesar-cipher-1.py
Strings	Easy	Mars Exploration	mars-exploration.py
Strings	Easy	HackerRank in a String!	hackerrank-in-a-string.py
Strings	Easy	Pangrams	pangrams.py
Strings	Easy	Weighted Uniform Strings	weighted-uniform-string.py
Strings	Easy	Separate the Numbers	separate-the-numbers.py
Strings	Easy	Funny String	funny-string.py
Strings	Easy	Gemstones	gem-stones.py
Strings	Easy	Alternating Characters	alternating-characters.py
Strings	Easy	Beautiful Binary String	beautiful-binary-string.py
Strings	Easy	The Love-Letter Mystery	the-love-letter-mystery.py
Strings	Easy	Palindrome Index	palindrome-index.py
Strings	Easy	Anagram	anagram.py
Strings	Easy	Making Anagrams	making-anagrams.py
Strings	Easy	Game of Thrones - I	game-of-thrones.py
Strings	Easy	Two Strings	two-strings.py
Strings	Easy	String Construction	string-construction.py
Strings	Easy	Strong Password	strong-password.py
Strings	Medium	Sherlock and Anagrams	sherlock-and-anagrams.py
Strings	Medium	Sherlock and the Valid String	sherlock-and-valid-string.py
Strings	Medium	Common Child	common-child.py
Sorting	Easy	Intro to Tutorial Challenges	tutorial-intro.py
Sorting	Easy	Insertion Sort - Part 1	insertionsort1.py
Sorting	Easy	Insertion Sort - Part 2	insertionsort2.py
Sorting	Easy	Correctness and the Loop Invariant	correctness-invariant.py
Sorting	Easy	Running Time of Algorithms	runningtime.py
Sorting	Easy	Quicksort 1 - Partition	quicksort1.py
Sorting	Easy	Counting Sort 1	countingsort1.py
Sorting	Easy	Counting Sort 2	countingsort2.py
Sorting	Easy	Closest Numbers	closest-numbers.py
Sorting	Easy	Find the Median	find-the-median.py
Sorting	Medium	The Full Counting Sort	countingsort4.py
Search	Easy	Ice Cream Parlor	icecream-parlor.py
Search	Easy	Missing Numbers	missing-numbers.py
Search	Easy	Sherlock and Array	sherlock-and-array.py
Search	Medium	KnightL on a Chessboard	knightl-on-chessboard.py
Search	Medium	Connected Cells in a Grid	connected-cell-in-a-grid.py
Search	Medium	Pairs	pairs.py
Graph Theory	Hard	Dijkstra: Shortest Reach 2	dijkstrashortreach.py
Greedy	Easy	Minimum Absolute Difference in an Array	minimum-absolute-difference-in-an-array.py
Greedy	Easy	Marc's Cakewalk	marcs-cakewalk.py
Greedy	Easy	Grid Challenge	grid-challenge.py
Greedy	Easy	Luck Balance	luck-balance.py
Greedy	Easy	Maximum Perimeter Triangle	maximum-perimeter-triangle.py
Greedy	Easy	Beautiful Pairs	beautiful-pairs.py
Greedy	Easy	Sherlock and The Beast	sherlock-and-the-beast.py
Greedy	Easy	Priyanka and Toys	priyanka-and-toys.py
Greedy	Easy	Largest Permutation	largest-permutation.py
Greedy	Easy	Mark and Toys	mark-and-toys.py
Greedy	Easy	Jim and the Orders	jim-and-the-orders.py
Greedy	Easy	Permuting Two Arrays	two-arrays.py
Greedy	Medium	Max Min	angry-children.py
Dynamic Programming	Medium	The Coin Change Problem	coin-change.py
Dynamic Programming	Medium	Equal	equal.py
Bit Manipulation	Easy	Lonely Integer	lonely-integer.py
Bit Manipulation	Easy	Maximizing XOR	maximizing-xor.py
Bit Manipulation	Easy	Sum vs XOR	sum-vs-xor.py
Bit Manipulation	Easy	Flipping bits	flipping-bits.py
Bit Manipulation	Medium	Counter game	counter-game.py
Bit Manipulation	Medium	Xor-sequence	xor-se.py
Bit Manipulation	Medium	The Great XOR	the-great-xor.py
Bit Manipulation	Medium	Yet Another Minimax Problem	yet-another-minimax-problem.py
Bit Manipulation	Medium	Sansa and XOR	sansa-and-xor.py
Bit Manipulation	Medium	AND Product	and-product.py
Bit Manipulation	Medium	Cipher	cipher.py
Recursion	Medium	The Power Sum	the-power-sum.py
Recursion	Medium	Recursive Digit Sum	recursive-digit-sum.py
Recursion	Medium	Password Cracker	password-cracker.py
Recursion	Hard	K Factorization	k-factorization.py
Recursion	Advanced	Repetitive K-Sums	repeat-k-sums.py
Game Theory	Easy	Game of Stones	game-of-stones-1.py
Game Theory	Easy	Tower Breakers	tower-breakers-1.py
Game Theory	Easy	A Chessboard Game	a-chessboard-game-1.py
Game Theory	Easy	Introduction to Nim Game	nim-game-1.py
Game Theory	Easy	Misère Nim	misere-nim-1.py
Game Theory	Easy	Poker Nim	poker-nim-1.py
Game Theory	Easy	Nimble Game	nimble-game-1.py

Data Structures

Subdomain	Difficulty	Challenge	Solution
Arrays	Easy	Arrays - DS	arrays-ds.py
Arrays	Easy	2D Array - DS	2d-array.py
Arrays	Easy	Dynamic Array	dynamic-array.py
Arrays	Easy	Left Rotation	array-left-rotation.py
Arrays	Medium	Sparse Arrays	sparse-arrays.py
Arrays	Hard	Array Manipulation	crush.py
Linked Lists	Easy	Print the Elements of a Linked List	print-the-elements-of-a-linked-list.py
Linked Lists	Easy	Insert a Node at the Tail of a Linked List	insert-a-node-at-the-tail-of-a-linked-list.py
Linked Lists	Easy	Insert a node at the head of a linked list	insert-a-node-at-the-head-of-a-linked-list.py
Linked Lists	Easy	Insert a node at a specific position in a linked list	insert-a-node-at-a-specific-position-in-a-linked-list.py
Linked Lists	Easy	Delete a Node	delete-a-node-from-a-linked-list.py
Linked Lists	Easy	Print in Reverse	print-the-elements-of-a-linked-list-in-reverse.py
Linked Lists	Easy	Reverse a linked list	reverse-a-linked-list.py
Linked Lists	Easy	Compare two linked lists	compare-two-linked-lists.py
Linked Lists	Easy	Merge two sorted linked lists	merge-two-sorted-linked-lists.py
Linked Lists	Easy	Get Node Value	get-the-value-of-the-node-at-a-specific-position-from-the-tail.py
Linked Lists	Easy	Delete duplicate-value nodes from a sorted linked list	delete-duplicate-value-nodes-from-a-sorted-linked-list.py
Linked Lists	Easy	Find Merge Point of Two Lists	find-the-merge-point-of-two-joined-linked-lists.py
Linked Lists	Easy	Inserting a Node Into a Sorted Doubly Linked List	insert-a-node-into-a-sorted-doubly-linked-list.py
Linked Lists	Easy	Reverse a doubly linked list	reverse-a-doubly-linked-list.py
Linked Lists	Medium	Cycle Detection	detect-whether-a-linked-list-contains-a-cycle.py
Trees	Easy	Tree: Preorder Traversal	tree-preorder-traversal.py
Trees	Easy	Tree: Postorder Traversal	tree-postorder-traversal.py
Trees	Easy	Tree: Inorder Traversal	tree-inorder-traversal.py
Trees	Easy	Tree: Height of a Binary Tree	tree-height-of-a-binary-tree.py
Trees	Easy	Tree : Top View	tree-top-view.py
Trees	Easy	Tree: Level Order Traversal	tree-level-order-traversal.py
Trees	Easy	Binary Search Tree : Insertion	binary-search-tree-insertion.py
Trees	Easy	Binary Search Tree : Lowest Common Ancestor	binary-search-tree-lowest-common-ancestor.py
Trees	Medium	Tree: Huffman Decoding	tree-huffman-decoding.py
Trees	Medium	Swap Nodes [Algo]	swap-nodes-algo.py
Trees	Medium	Is This a Binary Search Tree?	is-binary-search-tree.py
Balanced Trees	Medium	Self Balancing Tree	self-balancing-tree.c
Balanced Trees	Hard	Median Updates	median.py
Stacks	Easy	Maximum Element	maximum-element.py
Stacks	Easy	Equal Stacks	equal-stacks.py
Stacks	Medium	Balanced Brackets	balanced-brackets.py
Stacks	Medium	Game of Two Stacks	game-of-two-stacks.py
Stacks	Medium	Largest Rectangle	largest-rectangle.py
Stacks	Medium	Simple Text Editor	simple-text-editor.py
Stacks	Medium	Waiter	waiter.py
Stacks	Hard	Poisonous Plants	poisonous-plants.py
Stacks	Hard	AND xor OR	and-xor-or.py
Queues	Medium	Queue using Two Stacks	queue-using-two-stacks.py
Queues	Medium	Castle on the Grid	castle-on-the-grid.py
Queues	Medium	Down to Zero II	down-to-zero-ii.py
Queues	Hard	Truck Tour	truck-tour.py
Queues	Hard	Queries with Fixed Length	queries-with-fixed-length.py
Heap	Easy	QHEAP1	qheap1.py
Heap	Easy	Jesse and Cookies	jesse-and-cookies.py
Heap	Hard	Find the Running Median	find-the-running-median.py
Heap	Hard	Minimum Average Waiting Time	minimum-average-waiting-time.py
Disjoint Set	Medium	Components in a graph	components-in-graph.py
Disjoint Set	Hard	Merging Communities	merging-communities.py
Disjoint Set	Hard	Super Maximum Cost Queries	maximum-cost-queries.py
Multiple Choice	Hard	Data Structures MCQ 1	how-well-do-you-know-trees.py
Multiple Choice	Hard	Data Structures MCQ 2	are-you-an-expert-on-data-structures.py
Multiple Choice	Hard	Data Structures MCQ 3	are-you-an-expert-on-data-structures-1.py
Trie	Medium	Contacts	contacts.py
Trie	Hard	No Prefix Set	no-prefix-set.py
Advanced	Medium	Mr. X and His Shots	x-and-his-shots.py
Advanced	Medium	Jim and the Skyscrapers	jim-and-the-skyscrapers.py
Advanced	Medium	Find Maximum Index Product	find-maximum-index-product.py

Python

Subdomain	Difficulty	Challenge	Solution
Introduction	Easy	Say "Hello, World!" With Python	py-hello-world.py
Introduction	Easy	Python If-Else	py-if-else.py
Introduction	Easy	Arithmetic Operators	python-arithmetic-operators.py
Introduction	Easy	Python: Division	python-division.py
Introduction	Easy	Loops	python-loops.py
Introduction	Easy	Print Function	python-print.py
Introduction	Medium	Write a function	write-a-function.py
Basic Data Types	Easy	List Comprehensions	list-comprehensions.py
Basic Data Types	Easy	Find the Runner-Up Score!	find-second-maximum-number-in-a-list.py
Basic Data Types	Easy	Nested Lists	nested-list.py
Basic Data Types	Easy	Finding the percentage	finding-the-percentage.py
Basic Data Types	Easy	Lists	python-lists.py
Basic Data Types	Easy	Tuples	python-tuples.py
Strings	Easy	sWAP cASE	swap-case.py
Strings	Easy	String Split and Join	python-string-split-and-join.py
Strings	Easy	What's Your Name?	whats-your-name.py
Strings	Easy	Mutations	python-mutations.py
Strings	Easy	Find a string	find-a-string.py
Strings	Easy	String Validators	string-validators.py
Strings	Easy	Text Alignment	text-alignment.py
Strings	Easy	Text Wrap	text-wrap.py
Strings	Easy	Designer Door Mat	designer-door-mat.py
Strings	Easy	String Formatting	python-string-formatting.py
Strings	Easy	Alphabet Rangoli	alphabet-rangoli.py
Strings	Easy	Capitalize!	capitalize.py
Strings	Medium	The Minion Game	the-minion-game.py
Strings	Medium	Merge the Tools!	merge-the-tools.py
Sets	Easy	Introduction to Sets	py-introduction-to-sets.py
Sets	Easy	Symmetric Difference	symmetric-difference.py
Sets	Easy	Set .add()	py-set-add.py
Sets	Easy	Set .discard(), .remove() & .pop()	py-set-discard-remove-pop.py
Sets	Easy	Set .union() Operation	py-set-union.py
Sets	Easy	Set .intersection() Operation	py-set-intersection-operation.py
Sets	Easy	Set .difference() Operation	py-set-difference-operation.py
Sets	Easy	Set .symmetric_difference() Operation	py-set-symmetric-difference-operation.py
Sets	Easy	Set Mutations	py-set-mutations.py
Sets	Easy	The Captain's Room	py-the-captains-room.py
Sets	Easy	Check Subset	py-check-subset.py
Sets	Easy	Check Strict Superset	py-check-strict-superset.py
Sets	Medium	No Idea!	no-idea.py
Math	Easy	Polar Coordinates	polar-coordinates.py
Math	Easy	Mod Divmod	python-mod-divmod.py
Math	Easy	Power - Mod Power	python-power-mod-power.py
Math	Easy	Integers Come In All Sizes	python-integers-come-in-all-sizes.py
Math	Medium	Find Angle MBC	find-angle.py
Math	Medium	Triangle Quest 2	triangle-quest-2.py
Math	Medium	Triangle Quest	python-quest-1.py
Itertools	Easy	itertools.product()	itertools-product.py
Itertools	Easy	itertools.permutations()	itertools-permutations.py
Itertools	Easy	itertools.combinations()	itertools-combinations.py
Itertools	Easy	itertools.combinations_with_replacement()	itertools-combinations-with-replacement.py
Itertools	Medium	Compress the String!	compress-the-string.py
Itertools	Medium	Iterables and Iterators	iterables-and-iterators.py
Itertools	Hard	Maximize It!	maximize-it.py
Collections	Easy	collections.Counter()	collections-counter.py
Collections	Easy	DefaultDict Tutorial	defaultdict-tutorial.py
Collections	Easy	Collections.namedtuple()	py-collections-namedtuple.py
Collections	Easy	Collections.OrderedDict()	py-collections-ordereddict.py
Collections	Easy	Collections.deque()	py-collections-deque.py
Collections	Medium	Word Order	word-order.py
Collections	Medium	Company Logo	most-commons.py
Collections	Medium	Piling Up!	piling-up.py
Date and Time	Easy	Calendar Module	calendar-module.py
Date and Time	Medium	Time Delta	python-time-delta.py
Errors and Exceptions	Easy	Exceptions	exceptions.py
Errors and Exceptions	Easy	Incorrect Regex	incorrect-regex.py
Classes	Easy	Class 2 - Find the Torsional Angle	class-2-find-the-torsional-angle.py
Classes	Medium	Classes: Dealing with Complex Numbers	class-1-dealing-with-complex-numbers.py
Built-Ins	Easy	Zipped!	zipped.py
Built-Ins	Easy	Input()	input.py
Built-Ins	Easy	Python Evaluation	python-eval.py
Built-Ins	Easy	Any or All	any-or-all.py
Built-Ins	Medium	Athlete Sort	python-sort-sort.py
Built-Ins	Medium	ginortS	ginorts.py
Python Functionals	Easy	Map and Lambda Function	map-and-lambda-expression.py
Python Functionals	Medium	Validating Email Addresses With a Filter	validate-list-of-email-address-with-filter.py
Python Functionals	Medium	Reduce Function	reduce-function.py
Regex and Parsing	Easy	Detect Floating Point Number	introduction-to-regex.py
Regex and Parsing	Easy	Re.split()	re-split.py
Regex and Parsing	Easy	Group(), Groups() & Groupdict()	re-group-groups.py
Regex and Parsing	Easy	Re.findall() & Re.finditer()	re-findall-re-finditer.py
Regex and Parsing	Easy	Re.start() & Re.end()	re-start-re-end.py
Regex and Parsing	Easy	Validating Roman Numerals	validate-a-roman-number.py
Regex and Parsing	Easy	Validating phone numbers	validating-the-phone-number.py
Regex and Parsing	Easy	Validating and Parsing Email Addresses	validating-named-email-addresses.py
Regex and Parsing	Easy	Hex Color Code	hex-color-code.py
Regex and Parsing	Easy	HTML Parser - Part 1	html-parser-part-1.py
Regex and Parsing	Easy	HTML Parser - Part 2	html-parser-part-2.py
Regex and Parsing	Easy	Detect HTML Tags, Attributes and Attribute Values	detect-html-tags-attributes-and-attribute-values.py
Regex and Parsing	Easy	Validating UID	validating-uid.py
Regex and Parsing	Medium	Regex Substitution	re-sub-regex-substitution.py
Regex and Parsing	Medium	Validating Credit Card Numbers	validating-credit-card-number.py
Regex and Parsing	Hard	Validating Postal Codes	validating-postalcode.py
Regex and Parsing	Hard	Matrix Script	matrix-script.py
XML	Easy	XML 1 - Find the Score	xml-1-find-the-score.py
XML	Easy	XML2 - Find the Maximum Depth	xml2-find-the-maximum-depth.py
Closures and Decorators	Easy	Standardize Mobile Number Using Decorators	standardize-mobile-number-using-decorators.py
Closures and Decorators	Easy	Decorators 2 - Name Directory	decorators-2-name-directory.py
Numpy	Easy	Arrays	np-arrays.py
Numpy	Easy	Shape and Reshape	np-shape-reshape.py
Numpy	Easy	Transpose and Flatten	np-transpose-and-flatten.py
Numpy	Easy	Concatenate	np-concatenate.py
Numpy	Easy	Zeros and Ones	np-zeros-and-ones.py
Numpy	Easy	Eye and Identity	np-eye-and-identity.py
Numpy	Easy	Array Mathematics	np-array-mathematics.py
Numpy	Easy	Floor, Ceil and Rint	floor-ceil-and-rint.py
Numpy	Easy	Sum and Prod	np-sum-and-prod.py
Numpy	Easy	Min and Max	np-min-and-max.py
Numpy	Easy	Mean, Var, and Std	np-mean-var-and-std.py
Numpy	Easy	Dot and Cross	np-dot-and-cross.py
Numpy	Easy	Inner and Outer	np-inner-and-outer.py
Numpy	Easy	Polynomials	np-polynomials.py
Numpy	Easy	Linear Algebra	np-linear-algebra.py
Debugging	Medium	Words Score	words-score.py
Debugging	Medium	Default Arguments	default-arguments.py

Linux Shell

Subdomain	Difficulty	Challenge	Solution
Bash	Easy	Let's Echo	bash-tutorials-lets-echo.sh
Bash	Easy	Looping and Skipping	bash-tutorials---looping-and-skipping.sh
Bash	Easy	A Personalized Echo	bash-tutorials---a-personalized-echo.sh
Bash	Easy	Looping with Numbers	bash-tutorials---looping-with-numbers.sh
Bash	Easy	The World of Numbers	bash-tutorials---the-world-of-numbers.sh
Bash	Easy	Comparing Numbers	bash-tutorials---comparing-numbers.sh
Bash	Easy	Getting started with conditionals	bash-tutorials---getting-started-with-conditionals.sh
Bash	Easy	More on Conditionals	bash-tutorials---more-on-conditionals.sh
Bash	Medium	Arithmetic Operations	bash-tutorials---arithmetic-operations.sh
Bash	Medium	Compute the Average	bash-tutorials---compute-the-average.sh
Bash	Hard	Functions and Fractals - Recursive Trees - Bash!	fractal-trees-all.sh
Text Processing	Easy	Cut #1	text-processing-cut-1.sh
Text Processing	Easy	Cut #2	text-processing-cut-2.sh
Text Processing	Easy	Cut #3	text-processing-cut-3.sh
Text Processing	Easy	Cut #4	text-processing-cut-4.sh
Text Processing	Easy	Cut #5	text-processing-cut-5.sh
Text Processing	Easy	Cut #6	text-processing-cut-6.sh
Text Processing	Easy	Cut #7	text-processing-cut-7.sh
Text Processing	Easy	Cut #8	text-processing-cut-8.sh
Text Processing	Easy	Cut #9	text-processing-cut-9.sh
Text Processing	Easy	Head of a Text File #1	text-processing-head-1.sh
Text Processing	Easy	Head of a Text File #2	text-processing-head-2.sh
Text Processing	Easy	Middle of a Text File	text-processing-in-linux---the-middle-of-a-text-file.sh
Text Processing	Easy	Tail of a Text File #1	text-processing-tail-1.sh
Text Processing	Easy	Tail of a Text File #2	text-processing-tail-2.sh
Text Processing	Easy	'Tr' Command #1	text-processing-tr-1.sh
Text Processing	Easy	'Tr' Command #2	text-processing-tr-2.sh
Text Processing	Easy	'Tr' Command #3	text-processing-tr-3.sh
Text Processing	Easy	Sort Command #1	text-processing-sort-1.sh
Text Processing	Easy	Sort Command #2	text-processing-sort-2.sh
Text Processing	Easy	Sort Command #3	text-processing-sort-3.sh
Text Processing	Easy	Sort Command #4	text-processing-sort-4.sh
Text Processing	Easy	Sort Command #5	text-processing-sort-5.sh
Text Processing	Easy	'Sort' command #6	text-processing-sort-6.sh
Text Processing	Easy	'Sort' command #7	text-processing-sort-7.sh
Text Processing	Easy	'Uniq' Command #1	text-processing-in-linux-the-uniq-command-1.sh
Text Processing	Easy	'Uniq' Command #2	text-processing-in-linux-the-uniq-command-2.sh
Text Processing	Easy	'Uniq' Command #3	text-processing-in-linux-the-uniq-command-3.sh
Text Processing	Easy	'Uniq' Command #4	text-processing-in-linux-the-uniq-command-4.sh
Text Processing	Medium	Paste - 3	paste-3.sh
Text Processing	Medium	Paste - 4	paste-4.sh
Text Processing	Medium	Paste - 1	paste-1.sh
Text Processing	Medium	Paste - 2	paste-2.sh
Arrays in Bash	Easy	Read in an Array	bash-tutorials-read-in-an-array.sh
Arrays in Bash	Easy	Slice an Array	bash-tutorials-slice-an-array.sh
Arrays in Bash	Easy	Concatenate an array with itself	bash-tutorials-concatenate-an-array-with-itself.sh
Arrays in Bash	Easy	Display an element of an array	bash-tutorials-display-the-third-element-of-an-array.sh
Arrays in Bash	Easy	Count the number of elements in an Array	bash-tutorials-count-the-number-of-elements-in-an-array.sh
Arrays in Bash	Medium	Filter an Array with Patterns	bash-tutorials-filter-an-array-with-patterns.sh
Arrays in Bash	Medium	Remove the First Capital Letter from Each Element	bash-tutorials-remove-the-first-capital-letter-from-each-array-element.sh
Arrays in Bash	Hard	Lonely Integer - Bash!	lonely-integer-2.sh
Grep Sed Awk	Easy	'Grep' - A	text-processing-in-linux-the-grep-command-4.sh
Grep Sed Awk	Easy	'Grep' - B	text-processing-in-linux-the-grep-command-5.sh
Grep Sed Awk	Easy	'Sed' command #3	text-processing-in-linux-the-sed-command-3.sh
Grep Sed Awk	Hard	'Sed' command #4	sed-command-4.sh
Grep Sed Awk	Hard	'Sed' command #5	sed-command-5.sh
Grep Sed Awk	Medium	'Awk' - 1	awk-1.sh
Grep Sed Awk	Medium	'Awk' - 2	awk-2.sh
Grep Sed Awk	Medium	'Awk' - 3	awk-3.sh
Grep Sed Awk	Medium	'Awk' - 4	awk-4.sh
Grep Sed Awk	Medium	'Grep' #1	text-processing-in-linux-the-grep-command-1.sh
Grep Sed Awk	Medium	'Grep' #2	text-processing-in-linux-the-grep-command-2.sh
Grep Sed Awk	Medium	'Grep' #3	text-processing-in-linux-the-grep-command-3.sh
Grep Sed Awk	Medium	'Sed' command #1	text-processing-in-linux-the-sed-command-1.sh
Grep Sed Awk	Medium	'Sed' command #2	text-processing-in-linux-the-sed-command-2.sh

CPP

Subdomain	Difficulty	Challenge	Solution
Introduction	Easy	Say "Hello, World!" With C++	cpp-hello-world.cpp
Introduction	Easy	Input and Output	cpp-input-and-output.cpp
Introduction	Easy	Basic Data Types	c-tutorial-basic-data-types.cpp
Introduction	Easy	Conditional Statements	c-tutorial-conditional-if-else.cpp
Introduction	Easy	For Loop	c-tutorial-for-loop.cpp
Introduction	Easy	Functions	c-tutorial-functions.cpp
Introduction	Easy	Pointer	c-tutorial-pointer.cpp
Introduction	Easy	Arrays Introduction	arrays-introduction.cpp
Introduction	Easy	Variable Sized Arrays	variable-sized-arrays.cpp
Strings	Easy	StringStream	c-tutorial-stringstream.cpp
Strings	Easy	Strings	c-tutorial-strings.cpp
Classes	Easy	Structs	c-tutorial-struct.cpp
Classes	Easy	Class	c-tutorial-class.cpp
Classes	Easy	Classes and Objects	classes-objects.cpp
Classes	Easy	Box It!	box-it.cpp
Classes	Medium	Inherited Code	inherited-code.cpp
Classes	Medium	Exceptional Server	exceptional-server.cpp
Classes	Medium	Virtual Functions	virtual-functions.cpp
STL	Easy	Vector-Sort	vector-sort.cpp
STL	Easy	Vector-Erase	vector-erase.cpp
STL	Easy	Lower Bound-STL	cpp-lower-bound.cpp
STL	Easy	Sets-STL	cpp-sets.cpp
STL	Easy	Maps-STL	cpp-maps.cpp
STL	Easy	Print Pretty	prettyprint.cpp
STL	Medium	Deque-STL	deque-stl.cpp

C

Subdomain	Difficulty	Challenge	Solution
Introduction	Easy	"Hello World!" in C	hello-world-c.c
Introduction	Easy	Playing With Characters	playing-with-characters.c
Introduction	Easy	Sum and Difference of Two Numbers	sum-numbers-c.c
Introduction	Easy	Functions in C	functions-in-c.c
Introduction	Easy	Pointers in C	pointer-in-c.c
Conditionals and Loops	Easy	Conditional Statements in C	conditional-statements-in-c.c
Conditionals and Loops	Easy	For Loop in C	for-loop-in-c.c
Conditionals and Loops	Easy	Sum of Digits of a Five Digit Number	sum-of-digits-of-a-five-digit-number.c
Conditionals and Loops	Easy	Bitwise Operators	bitwise-operators-in-c.c
Conditionals and Loops	Medium	Printing Pattern using Loops	printing-pattern-2.c
Arrays and Strings	Medium	1D Arrays in C	1d-arrays-in-c.c
Arrays and Strings	Medium	Array Reversal	reverse-array-c.c
Arrays and Strings	Medium	Printing Tokens	printing-tokens-.c
Arrays and Strings	Medium	Digit Frequency	frequency-of-digits-1.c
Arrays and Strings	Medium	Dynamic Array in C	dynamic-array-in-c.c
Functions	Easy	Calculate the Nth term	recursion-in-c.c
Functions	Easy	Students Marks Sum	students-marks-sum.c
Functions	Medium	Permutations of Strings	permutations-of-strings.c
Functions	Medium	Variadic functions in C	variadic-functions-in-c.c
Functions	Hard	Sorting Array of Strings	sorting-array-of-strings.c
Structs and Enums	Easy	Boxes through a Tunnel	too-high-boxes.c
Structs and Enums	Medium	Small Triangles, Large Triangles	small-triangles-large-triangles.c
Structs and Enums	Hard	Post Transition	post-transition.c

Interview Preparation Kit

Subdomain	Difficulty	Challenge	Solution
Warmup	Easy	Counting Valleys	counting-valleys.py
Warmup	Easy	Jumping on the Clouds	jumping-on-the-clouds.py
Warmup	Easy	Repeated String	repeated-string.py
Warmup	Easy	Sock Merchant	sock-merchant.py
Arrays	Easy	2D Array - DS	2d-array.py
Arrays	Easy	Arrays: Left Rotation	ctci-array-left-rotation.py
Arrays	Medium	Minimum Swaps 2	minimum-swaps-2.py
Arrays	Medium	New Year Chaos	new-year-chaos.py
Arrays	Hard	Array Manipulation	crush.py
Dictionaries and Hashmaps	Easy	Hash Tables: Ransom Note	ctci-ransom-note.py
Dictionaries and Hashmaps	Easy	Two Strings	two-strings.py
Dictionaries and Hashmaps	Medium	Count Triplets	count-triplets-1.py
Dictionaries and Hashmaps	Medium	Frequency Queries	frequency-queries.py
Dictionaries and Hashmaps	Medium	Sherlock and Anagrams	sherlock-and-anagrams.py
Graphs	Hard	BFS: Shortest Reach in a Graph	ctci-bfs-shortest-reach.py
Graphs	Hard	DFS: Connected Cell in a Grid	ctci-connected-cell-in-a-grid.py
Greedy Algorithms	Easy	Luck Balance	luck-balance.py
Greedy Algorithms	Easy	Minimum Absolute Difference in an Array	minimum-absolute-difference-in-an-array.py
Greedy Algorithms	Medium	Greedy Florist	greedy-florist.py
Greedy Algorithms	Medium	Max Min	angry-children.py
linked Lists	Easy	Find Merge Point of Two Lists	find-the-merge-point-of-two-joined-linked-lists.py
Linked Lists	Easy	Insert a node at a specific position in a linked list	insert-a-node-at-a-specific-position-in-a-linked-list.py
Linked Lists	Easy	Inserting a Node Into a Sorted Doubly Linked List	insert-a-node-into-a-sorted-doubly-linked-list.py
Linked Lists	Easy	Linked Lists: Detect a Cycle	ctci-linked-list-cycle.py
Linked Lists	Easy	Reverse a doubly linked list	reverse-a-doubly-linked-list.py
Miscellaneous	Easy	Flipping bits	flipping-bits.py
Miscellaneous	Medium	Time Complexity: Primality	ctci-big-o.py
Recursion and Backtracking	Easy	Recursion: Fibonacci Numbers	ctci-fibonacci-numbers.py
Recursion and Backtracking	Medium	Recursion: Davis' Staircase	ctci-recursive-staircase.py
Recursion and Backtracking	Medium	Recursive Digit Sum	recursive-digit-sum.py
Search	Medium	Hash Tables: Ice Cream Parlor	ctci-ice-cream-parlor.py
Search	Medium	Swap Nodes [Algo]	swap-nodes-algo.py
Search	Medium	Pairs	pairs.py
Search	Medium	Triple sum	triple-sum.py
Search	Medium	Minimum Time Required	minimum-time-required.py
Sorting	Easy	Mark and Toys	mark-and-toys.py
Sorting	Easy	Sorting: Bubble Sort	ctci-bubble-sort.py
Sorting	Medium	Fraudulent Activity Notifications	fraudulent-activity-notifications.py
Sorting	Medium	Sorting: Comparator	ctci-comparator-sorting.py
Sorting	Hard	Merge Sort: Counting Inversions	ctci-merge-sort.py
Stacks and Queues	Medium	Balanced Brackets	balanced-brackets.py
Stacks and Queues	Medium	Castle on the Grid	castle-on-the-grid.py
Stacks and Queues	Medium	Largest Rectangle	largest-rectangle.py
Stacks and Queues	Medium	Queues: A Tale of Two Stacks	ctci-queue-using-two-stacks.py
Stacks and Queues	Hard	Poisonous Plants	poisonous-plants.py
Strings	Easy	Alternating Characters	alternating-characters.py
Strings	Easy	Strings: Making Anagrams	ctci-making-anagrams.py
Strings	Medium	Sherlock and the Valid String	sherlock-and-valid-string.py
Strings	Medium	Special Palindrome Again	special-palindrome-again.py
Strings	Medium	Common Child	common-child.py
Trees	Easy	Binary Search Tree : Lowest Common Ancestor	binary-search-tree-lowest-common-ancestor.py
Trees	Easy	Tree: Height of a Binary Tree	tree-height-of-a-binary-tree.py
Trees	Medium	Tree: Huffman Decoding	tree-huffman-decoding.py
Trees	Medium	Trees: Is This a Binary Search Tree?	ctci-is-binary-search-tree.py