problems.md

Problems List

Algorithms and Data Structure

Title	Difficulty	Source	Tags	C# Solution	Java Solution	JS Solution	Python Solution	Go Solution
Array
Chunk array	Easy	N/A	Array	ArrayChunk.cs	ArrayChunk.java	chunk.js	array_chunk.py	chunk.go
Intersection of two arrays	Easy	Leetcode	Array	Intersect.cs	Intersect.java	intersect.js	intersect.py
Check if an array is sorted	Easy	N/A	Array	IsSorted.cs	IsSorted.java	issorted.js	is_sorted.py
Create a spiral matrix	Medium	N/A	Array	Matrix.cs	Matrix.java	matrix.js	matrix.py
Maximum subarray mod sum	Hard	HackerRank	Array	MaxSubArrayModSum.cs	MaxSubArrayModSum.java	maxSubArrayModSum.js	max_subarray_modsum.py
Maximum subarray sum	Medium	Leetcode	Array	MaxSubArraySum.cs	MaxSubArraySum.java	maxSubArraySum.js	max_subarray_sum.py
Missing number in array	Easy	N/A	Array	Missing.cs	Missing.java	missing.js	missing.py
Move zeroes	Easy	Leetcode	Array	MovingZeroes.cs	MovingZeroes.java	moveZeroes.js	moving_zeroes.py
Plus one	Medium	Leetcode	Array	PlusOne.cs	PlusOne.java	plusOne.js	plus_one.py
Remove duplicates from sorted array	Easy	Leetcode	Array	RemoveDuplicates.cs	RemoveDuplicates.java	removeDuplicates.js	remove_duplicates.py
Rotate an array	Medium	Leetcode	Array	RotateArray.cs	RotateArray.java	rotateArray.js	rotate_array.py
Rotate image	Medium	Leetcode	Array	RotateImage.cs	RotateImage.java	rotateImage.js	rotate_image.py
Sock merchant	Easy	HackerRank	Array	SockMerchant.cs	SocketMerchant.java	sockMerchant.js	sock_merchant.py
Triple sum	Medium	HackerRank	Array	TripleSum.cs	TripleSum.java	tripleSum.js	triple_sum.py
Two sum	Easy	Leetcode	Array	TwoSum.cs	TwoSum.java	twoSum.js	two_sum.py
Two sum - 1	Medium	FreeCodeCamp	Array			twoSum1.js
Valid Sodoku	Medium	Leetcode	Array	ValidSudoku.cs	ValidSudoku.java	validSudoku.js	validate_sudoku.py
Assorted
Crossword puzzle	Hard	HackerRank	Assorted	N/A	N/A	crosswordPuzzle.js	N/A
Make candies	Hard	HackerRank	Assorted	MakeCandies.cs	MakeCandies.java	makeCandies.js	make_candies.py
Max profit	Medium	Leetcode	Assorted	MaxProfit.cs	MaxProfit.java	maxProfit.js	max_profit.py
Minimum time	Medium	HackerRank	Assorted	MinTime.cs	MinTime.java	minTime.js	min_time.py
Draw pyramid	Easy	N/A	Assorted	Pyramid.cs	DrawPyramid.java	pyramid.js	pyramid.py
Draw steps	Easy	N/A	Assorted	Steps.cs	DrawSteps.java	steps.js	steps.py
Update inventory	Easy	FreeCodeCamp	Hash Table, Array			updateInventory.js
Opened doors	Medium	FreeCodeCamp	Rosetta			openedDoors.js
Dynamic
Grid traveler	Medium	N/A	Dynamic	GridTraveler.cs	GridTraveler.java	gridTraveler.js	grid_traveler.py
If a target number can be generated by adding numbers from a given array	Hard	N/A	Dynamic	CanSum.cs	CanSum.java	canSum.js	can_sum.py
Get all the combinations of numbers from a given array that can add up to the target number	Hard	N/A	Dynamic	HowSum.cs	HowSum.java	howSum.js	how_sum.py
Get the shortest combination of numbers from a given array that can add up to the target number	Hard	N/A	Dynamic	BestSum.cs	BestSum.java	bestSum.js	best_sum.py
If a target string can be constructed by the strings from a given array	Hard	N/A	Dynamic	CanConstruct.cs	CanConstruct.java	canConstruct.js	can_construct.py
Get all the combinations of strings from a given array that can construct to the target string	Hard	N/A	Dynamic	AllConstruct.cs	AllConstruct.java	allConstruct.js	all_construct.py
Count the number of combinations of strings from a given array that can construct to the target string	Hard	N/A	Dynamic	CountConstruct.cs	CountConstruct.java	countConstruct.js	count_construct.py
Longest common substring	Hard	HackerRank	Dynamic	CommonChild.cs	CommonChild.java	commonChild.js	common_child.py
Greedy
Greedy florist	Medium	HackerRank	Greedy	GreedyFlorist.cs	GreedyFlorist.java	greedyFlorist.js	greedy_florist.py
Luck Balance	Easy	HackerRank	Greedy	LuckBalance.cs	LuckBalance.java	luckBalance.js	luck_balance.py
Max Min	Medium	HackerRank	Greedy	MaxMin.cs	MaxMin.java	maxMin.js	max_min.py
Minimum absolute difference	Easy	HackerRank	Greedy	MinimumAbsoluteDifference.cs	MinimumAbsoluteDifference.java	minimumAbsoluteDifference.js	min_absolute_diff.py
Reverse shuffle merge	Hard	HackerRank	Greedy	ReverseShuffleMerge.cs	ReverseShuffleMerge.java	reverseShuffleMerge.js	reverse_shuffle_merge.py
Math
Find out combinations	Hard	N/A	Math, Dynamic			combinations.js
Factorial	Easy	N/A	Math, Dynamic			factorial.js
The sum of even numbers in a Fibonacci sequence	Medium	FreeCodeCamp	Math			fiboEvenSum.js
Fibonacci	Easy	N/A	Dynamic, Math	Fibonacci.cs	Fibonacci.java	fibonacci.js	fibonacci.py
Fizzbuzz	Easy	N/A	Math	Fizzbuzz.cs	Fizzbuzz.java	fizzbuzz.js	fizzbuzz.py
Integer partition	Hard	N/A	Math, Dynamic			integerPartition.js
Count integer partitions	Hard	FreeCodeCamp	Math			countIntegerPartitions.js
Is prime number	Easy	N/A	Math	IsPrime.cs	IsPrime.java	isprime.js	is_prime.py	is_prime.go
Find out permutations	Hard	Leetcode	Dynamic, Math	Permutations.cs	Permutations.java	permutations.js	permutations.py
No repeated consecutive permutations	Hard	FreeCodeCamp	Math, Dynamic			noRepeatPermutations.js
Symmectric difference	Medium	FreeCodeCamp	Math, Dynamic			symmetricDiff.js
Solve24	Hard	FreeCodeCamp	Rosetta			solve24.js
String
Anagrams	Easy	Leetcode	String, Hash table	Anagrams.cs	Anagrams.java	anagrams.js	anagrams.py
Capitalize a string	Easy	N/A	String	Capitalize.cs	Capitalize.java	capitalize.js	capitalize.py
Check permutations	Easy	N/A	String, Hash table	CheckPermutations.cs	CheckPermutations.java	checkPermutation.js	permutation.py
Defanging IP	Easy	Leetcode	String	DefangingIP.cs	DefangingIP.java	defangingIP.js	defanging_ip.py
First unique character in a string	Easy	Leetcode	String, Hash table	FirstUniqueChar.cs	FirstUniqueChar.cs	firstUniqueChar.js	first_unique_char.py
Is curly braces balanced	Easy	N/A	String	IsBalanced.cs	IsBalanced.java	isBalanced.js	balanced.py
All characters are unique in a string	Easy	N/A	String, Hash table	IsUnique.cs	IsUnique.java	isUnique.js	unique.py
Longest palindrome substring	Medium	Leetcode	String			longestPalindromeSubstring.js
Longest substring without repeat characters	Medium	Leetcode	String, Sliding window			longestSubstring.js
Making anagrams	Medium	HackerRank	String, Hash table	MakeAnagrams.cs	MakeAnagrams.java	makeAnagrams.js	make_anagrams.py
Most commonly used character in a string	Easy	N/A	String, Hash table	MaxChar.cs	MaxChar.java	maxChar.js	max_char.py
One away	Medium	N/A	String	OneAway.cs	OneAway.java	oneAway.js	one_away.py
Check if a string is palindrome	Easy	N/A	String	Palindrome.cs	Palindrome.java	palindrome.js	palindrome.py
Check if a string is a permutation of a palindrome	Easy	N/A	String, Hash table	PalindromePermutation.cs	PalindromePermutation.java	palindromePermutation.js	palindrome_permutation.py
Remove vowels from a string	Easy	N/A	String	RemoveVowels.cs	RemoveVowels.java	removeVowels.js	remove_vowels.py
Reverse an integer	Easy	N/A	String	ReverseInt.cs	ReverseInteger.java	reverseint.js	reverse_int.py
Reverse a string	Easy	N/A	String	ReverseStr.cs	ReverseString.java	reversestring.js	reverse_string.py
Special palindrome	Medium	HackerRank	String	SpecialString.cs	SpecialString.java	specialString.js	special_string.py
String compression	Easy	N/A	String	StringCompression.cs	StringCompression.java	stringCompression.js	string_compress.py
String rotation	Easy	N/A	String	StringRotation.cs	StringRotation.java	stringRotation.js	string_rotation.py
Convert string to integer	Easy	Leetcode	String			stringToInteger.js
All characters appear same time in a string	Medium	HackerRank	String	ValidString.cs	ValidString.java	validString.js	valid_string.py
Get the number of vowels in a string	Easy	N/A	String	Vowels.cs		vowels.js	count_vowels.py
Convert a string in a zigzag pattern	Easy	Leetcode	String			zigzagConversion.js
DS - Graph
Implement a graph and relevant methods	Medium	N/A	Graph	Graph.cs	Graph.java	graph.js	graph.py
DS - Hash table
Implement hash table and relevant methods	Medium	N/A	Hash table	HashTable.cs	HashTable.java	hashTable.js	hash.py
DS - Linked list
Implement linked list and relevant methods	Medium	N/A	Linked list	MyLinkedList.cs	MyLinkedList.java	linkedlist.js	linkedlist.py
Implement doubly linked list and relevant methods	Medium	N/A	Linked list			doublyLinkedList.js
Check if a linked list is circular	Medium	N/A	Linked list	Circular.cs	Circular.java	circular.js	circular.py
Get the last n-th node of a linked list	Medium	N/A	Linked list	SearchFromLast.cs	SearchFromLast.java	fromlast.js	fromlast.py
Get the middle node of a linked list	Medium	N/A	Linked list	MidPoint.cs	MidPoint.java	midpoint.js	midpoint.py
Partition a linked list by a given number	Hard	N/A	Linked list	Partition.cs	Partition.java	partition.js	partition.py
Remove duplicate nodes from a linked list	Medium	N/A	Linked list	RemoveDuplicate.cs	RemoveDuplicate.java	removeDuplicate.js	remove_duplicate.py
Sum two numbers represented by linked list	Hard	N/A	Linked list	SumLists.cs	SumLists.java	sumLists.js	sumlists.py
DS - Tree
Implement a tree	Medium	N/A	Tree	Tree.cs	Tree.java	tree.js	tree.py
Implement a binary search tree	Medium	N/A	Tree	BinarySearchTree.cs	Bst.java	bst.js	bst.py
Validate a binary search tree	Medium	N/A	Tree	BinarySearchTree.cs	Bst.java	bst-val.js	bst_val.py
Implement three ways to traverse a binary tree	Medium	N/A	Tree	BTreeTraverse.cs	BTreeTraverse.java	bTreeTraverse.js	btree_traverse.py
The width of each level of a tree	Hard	N/A	Tree	N/A	LevelWidth.java	levelwidth.js	levelwidth.py
Read all nodes of a binary search tree	Hard	N/A	Tree	ListOfDepths.cs	ListOfDepths.java	listOfDepth.js	depthslist.py
Create a binary search tree with minimal height	Hard	N/A	Tree	MinimalTree.cs	MinimalBst.java	minimalTree.js	minimal_bst.py
Swap nodes of a tree	Hard	HackerRank	Tree	SwapNodes.cs	SwapNodes.java	swapNodes.js	swap_nodes.py
Implement a trie	Hard	FreeCodeCamp	Tree			trie.js
DS - Stack and Queue
Implement a stack and relevant methods	Easy	N/A	Stack			stack.js	stack.py
Implement a queue and relevant methods	Easy	N/A	Queue			queue.js	queue.py
Animal queue	Medium	N/A	Queue	AnimalQueue.cs	AnimalQueue.java	animalQueue.js	animal_queue.py
Priority queue	Medium	FreeCodeCamp	Queue			priorityQueue.js
Circular queue	Medium	FreeCodeCamp	Queue			circularQueue.js
Get the minimum number of a stack	Easy	N/A	Stack	GetMin.cs	GetMin.java	getMin.js	get_min.py
Check if a string has balanced brackets	Medium	HackerRank	Stack	IsBalanced.cs	IsBalanced.java	isBalanced2.js	is_balanced.py
Largest rectangle	Medium	Leetcode	Stack	LargestRectangle.cs	LargestRectangle.java	largestRectangle.js	largest_rectangle.py
Queue from stack	Medium	N/A	Stack, Queue	QueueFromStack.cs	QueueFromStack.java	qfroms.js	queue_from_stack.py
Set of stacks	Medium	N/A	Stack	SetOfStacks.cs	SetOfStacks.java	setOfStacks.js	stack_set.py
Sort a stack	Medium	N/A	Stack	SortStack.cs	SortStack.java	sortStack.js	sort_stack.py
Weave two queues	Medium	N/A	Queue	Weave.cs	Weave.java	weave.js	weave.py
Linear search	Easy	N/A	Searching	LinearSearch.cs	LinearSearch.java	linearSearch.js	linear_search.py
DS - Set
Implement a set	Easy	N/A	Set			set.js
DS - Heap
Implement a max heap and its relevant methods	Easy	N/A	Heap			maxHeap.js
Implement a min heap and its relevant methods	Easy	N/A	Heap			minHeap.js
Searching
Binary search	Medium	N/A	Searching	BinarySearch.cs	BinarySearch.java	binarySearch.js	binary_search.py
Jump search	Medium	N/A	Searching	JumpSearch.cs	JumpSearch.java	jumpSearch.js	jump_search.py
Interpolation Search	Medium	N/A	Searching	InterpolationSearch.cs	InterpolationSearch.java	interpolationSearch.js	interpolation_search.py
Exponential search	Medium	N/A	Searching	ExponentialSearch.cs	ExponentialSearch.java	exponentialSearch.js	exponential_search.py
Sorting
Bubble sort	Medium	N/A	Sorting	Sorting.cs	BubbleSort.java	bubbleSort.js	bubble_sort.py
Counting sort	Medium	N/A	Sorting	CountingSort.cs	CountingSort.java	countingSort.js	counting_sort.py
Merge sort	Hard	N/A	Sorting	Sorting.cs	MergeSort.java	mergeSort.js	merge_sort.py
Quick sort	Medium	N/A	Sorting			quickSort.js
Selection sort	Hard	N/A	Sorting	Sorting.cs	SelectionSort.java	selectionSort.js	selection_sort.py
Find the median of two sorted arrays	Medium	Leetcode	Sorting			medianSorted.js
Get how many times of inversions required to sort an array	Hard	HackerRank	Sorting	CountInversions.cs	CountInversions.java	countInversions.js	count_inversions.py
Fradulent activity notice	Hard	HackerRank	Sorting	FradulentActivityNotice.cs	FradulentActivityNotice.java	fradulentActivityNotice.js	fradulent_activity_notice.py
JS specific
Implement Array.prototype.at method	Easy	GreatFrontEnd	JS Polyfills	N/A	N/A	arrayAt.js	N/A
Implement Array.prototype.map method	Easy	GreatFrontEnd	JS Polyfills	N/A	N/A	arrayMap.js	N/A
Implement Lodash function: countBy	Easy	GreatFrontEnd	Lodash	N/A	N/A	countBy.js	N/A
Implement Lodash curry function	Hard	GreatFrontEnd	Lodash	N/A	N/A	curry.js	N/A
Implement Lodash function: debounce function	Medium	GreatFrontEnd	Lodash	N/A	N/A	debounce.js	N/A
Deep clone an object	Hard	GreatFrontEnd	Lodash	N/A	N/A	deepClone.js	N/A
Creat an event library	Hard	GreatFrontEnd	JS Polyfills	N/A	N/A	events.js	N/A
Implement Array.prototype.filter method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	filter.js	N/A
Implement Array.prototype.findIndex method	Easy	GreatFrontEnd	JS Polyfills	N/A	N/A	findIndex.js	N/A
Implement Array.prototype.findLastIndex method	Easy	GreatFrontEnd	JS Polyfills	N/A	N/A	findLastIndex.js	N/A
Flatten an array	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	flatten.js	N/A
Implement Function.prototype.apply method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	functionApply.js	N/A
Implement Function.prototype.call method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	functionCall.js	N/A
Implement Lodash function: get	Medium	GreatFrontEnd	Lodash	N/A	N/A	get.js	N/A
Implement Lodash function: groupBy	Medium	GreatFrontEnd	Lodash	N/A	N/A	groupBy.js	N/A
Implement Array.prototype.indexOf method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	indexof.js	N/A
Implement Lodash function: intersectionBy	Easy	GreatFrontEnd	Lodash	N/A	N/A	intersectionBy.js	N/A
Implement Lodash function: intersectionWith	Hard	GreatFrontEnd	Lodash	N/A	N/A	intersectionWith.js	N/A
Implement Lodash function: once	Hard	GreatFrontEnd	Lodash	N/A	N/A	once.js	N/A
Implement Promise.all method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	promiseAll.js	N/A
Implement Promise.allSettled method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	promiseAllSettled.js	N/A
Implement Promise.any method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	promiseAny.js	N/A
Implement Promise.race method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	promiseRace.js	N/A
Implement Array.prototype.reduce method	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	reduce.js	N/A
Implement type check utility functions	Medium	GreatFrontEnd	JS Polyfills	N/A	N/A	typeUtilities.js	N/A