Algorithmic Coding

Solve coding challenges involving performance-optimized data structures and algorithms.
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Questions List

Data Structures and Algorithms InterviewsFront end engineer's guide to DSA - important concepts to know, top practice questions to do and other tips
Guide
GUIDES
  • Selection SortImplement a function that performs a selection sort
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  • StackImplement a stack data structure containing the common stack methods
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  • Count Set Bits in a Binary NumberImplement a function to find set bits in binary representation of a given integer
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  • Find Duplicates in ArrayImplement a function to check if there are any duplicate numbers in the array
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  • Find Missing Number in SequenceImplement a function to find the missing element in a sorted array
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  • Insertion SortImplement a function that performs an insertion sort
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  • Optimal Stock TradingImplement a function to find the maximum profit achievable by buying and selling a stock once
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  • Pair sumImplement a function to find two numbers within an array of integers that add up to a target integer
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  • String AnagramImplement a function to determine if two strings are anagram of each other
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  • Binary Tree Maximum DepthImplement a function to find the maximum depth of a binary tree
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  • Flip Binary TreeImplement a function to flip the nodes in a binary tree
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  • Staircase Climbing CombinationsImplement a function to find the number of ways to reach at the top of staircase
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  • Balanced BracketsImplement a function to determine if a string contains balanced brackets
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  • Binary Tree EqualImplement a function to determine whether two binary trees are equal
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  • Bit CountingImplement a function to find number of set bits from 0 to n
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  • Bit ReversalImplement a function to flip the order of the bits in a given number
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  • Linked List ReversalImplement a function to reverse a linked list
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  • String PalindromeImplement a function to determine if a string is a palindrome
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  • Linked List Detect CycleImplement a function to detect if there are cycles in a linked list
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  • Binary Tree SubtreeImplement a function to check if a binary tree is a subtree of another binary tree
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  • Linked Lists Combine Two SortedImplement a function to combine two sorted linked list
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  • Meeting CalendarImplement a function to check if all meetings can be attended
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  • Array Product Excluding CurrentImplement a function to find the product of elements in an array excluding the current element
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  • Binary SearchImplement a function that performs binary search on an array of numbers
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  • Breadth-first SearchImplement a breadth-first search algorithm that traverses a directed graph in a breadth-first manner
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  • Depth-first SearchImplement a depth-first search algorithm that traverses a directed graph in a depth-first manner
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  • Heap SortImplement a function that performs a heap sort
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  • Is the Graph a TreeImplement a function to determine if a graph is a valid tree
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  • Maximum Water Trapped Between WallsImplement a function to find the maximum water volume between two walls in an array of walls
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  • QueueImplement a queue data structure containing the common queue methods
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  • Merge SortImplement a function that performs a recursive merge sort
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  • Quick SortImplement a function that performs a recursive quick sort
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  • Topological SortImplement a function that performs a topological sort
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  • Binary Tree Level Order TraversalImplement a function to find the level order traversal of a binary tree
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  • Maximum Sum in Contiguous ArrayImplement a function to find the subarray with the maximum sum
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  • Smallest element in rotated sorted arrayImplement a function to find the smallest element in rotated sorted array
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  • Find Element in Rotated ArrayImplement a function to find an integer in a rotated sorted array
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  • Maximum Product in Contiguous ArrayImplement a function to find the subarray which has the largest product
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  • Binary Search Tree Kth Smallest ElementImplement a function to find the kth smallest node in a BST
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  • Binary Search Tree Lowest Common AncestorImplement a function to find the LCA in a binary search tree
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  • Count Islands in a GridImplement a function to count distinct islands in a 2D binary grid
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  • Delete Nth Node from End of Linked ListImplement a function to delete the nth node from the end of a linked list
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  • Distinct Paths in GridImplement a function to calculate distinct paths for a robot moving on an m x n grid
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  • Matrix ZeroingImplement a function to set matrix rows and columns to zero
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  • Merge Overlapping IntervalsImplement a function to merge overlapping intervals
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  • Most Common ElementsImplement a function to determine the most common elements in an integer array
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  • Neighborhood TheftImplement a function to find maximum money to rob without alerting police
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  • Rearrange Linked ListImplement a function to rearrange the nodes in a linked list
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  • Sum Without AdditionImplement a function to find the sum of two integers without using + and - operator
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  • Triplet SumImplement a function to find all unique triplets with distinct indices that sum to 0
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  • Validate Binary Search TreeImplement a function to validate whether a binary tree is a valid binary search tree
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  • Combinations for Target SumImplement a function to count combinations that sum to the target
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  • Course DependencyImplement a function to check if all courses can be completed given prerequisites
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  • Decode MessageImplement a function to count ways to decode a numeric string
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  • Longest Consecutive Number SequenceImplement a function to find the length of the longest consecutive number sequence
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  • NEW
    Longest Increasing SubsequenceImplement a function to find the length of the longest increasing subsequence
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  • NEW
    Minimum Coins for ChangeImplement a function to return minimum coins needed to make the given amount
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  • Palindromic SubstringsImplement a function to count all palindromic substrings in a string
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  • Segment WordsImplement a function to check whether a string be formed from dictionary words
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  • String Anagram GroupsImplement a function to group an array of strings into anagrams
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  • Task CoordinationImplement a function to find minimum intervals for tasks with cooldown
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  • Trie (Prefix Tree)Implement a trie-prefix-tree with insert, search, and starts with functionality
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  • Binary Tree Rebuilding from Preorder and Inorder TraversalsImplement a function to construct a binary tree from preorder and inorder traversals
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  • Disjoint IntervalsImplement a function to determine the minimum amount of removals to get non-overlapping intervals
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  • End of Array ReachableImplement a function to determine if the end of the array is reachable
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  • Find the Longest Palindromic SubstringImplement a function to find the longest palindromic substring
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  • Find Word in GridImplement a function to check the existence of a word in a grid
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  • Graph Count Connected ComponentsImplement a function to count connected components in a graph
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  • Longest Common SubsequenceImplement a function to find the longest common subsequence in two strings
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  • Longest Non-repeating SubstringImplement a function to find the length of longest substring with unique characters
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  • Longest Repeating Substring After ReplacementsImplement a function to find the longest uniform substring after up to k replacements
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  • Matrix RotationImplement a function to rotate the given matrix by 90 degrees
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  • Matrix Spiral TraversalImplement a function to traverse the matrix in spiral order
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  • Merge New IntervalImplement a function to insert a new interval in the given intervals
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  • Neighborhood Theft (Circular)Implement a function to find maximum money to rob in circular houses without alerting police
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  • Ocean FlowImplement a function returning cells with water flow to both oceans
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  • Word FinderImplement a data structure where words can be added and support wildcard searching
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  • Graph CloneImplement a function to deeply clone a connected and undirected graph
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  • Minimum Meeting Rooms NeededImplement a function to find the minimum number of required conference rooms
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  • Binary Tree Serialization and DeserializationImplement a function to serialize and deserialize a binary tree
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  • Binary Tree Maximum Total PathImplement a function to find the maximum total of nodes in a binary tree path
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  • Find Words in GridImplement a function to find all the words present in the grid
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  • Linked Lists Combine K SortedImplement a function to combine k sorted linked lists
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  • Shortest Substring Containing CharactersImplement a function to return the smallest substring of a string containing all characters from another string
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  • Extraterrestrial LanguageImplement a function to verify and return an extraterrestrial language's alphabet order
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  • Number Stream MedianImplement a function to find the median of a dynamic stream of integers
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Algorithmic Coding Interview Questions for Front End Interviews

Algorithmic coding is a critical skill for front end developers, as it demonstrates your ability to solve complex problems efficiently—an essential aspect of technical interviews. These questions are designed to test your understanding of core data structures, algorithms, and your ability to apply them to real-world scenarios. Mastering these concepts is key to performing well in front end interviews, where you may be asked to solve challenges that range from manipulating data structures to optimizing performance.

Our Algorithmic Coding questions are meticulously crafted to help you build and refine these essential skills. You'll encounter a wide variety of problems that challenge your knowledge of algorithms such as sorting, searching, and recursion, as well as data structures like arrays, linked lists, trees, and graphs. These questions are aligned with what's currently being asked in front end interviews, ensuring that your preparation is both relevant and effective.

What You'll Learn

  • Data Structures: Understand and implement key data structures such as arrays, linked lists, trees, and graphs. Learn how to use these structures to store and manipulate data efficiently.

  • Algorithm Design: Master the design of algorithms for tasks like sorting, searching, and traversing data structures. Practice developing algorithms that are both correct and optimized for performance.

  • Problem-Solving Techniques: Enhance your problem-solving skills by tackling a range of algorithmic challenges, from simple exercises to complex problems that require innovative solutions.

  • Complexity Analysis: Learn to analyze the time and space complexity of your algorithms, ensuring they meet the efficiency requirements expected in high-stakes interviews.

Key Features

  1. Crafted by industry experts: Every algorithmic coding question, along with its solution and test cases, has been meticulously developed by engineers with extensive experience in interviewing candidates at top tech companies. Their insights ensure that the questions are current and reflect the challenges you'll face in real interviews.

  2. Comprehensive question set: This focus area offers a diverse collection of algorithmic coding problems that range in difficulty and cover a broad spectrum of topics. These problems are carefully selected to help you build proficiency in the algorithmic concepts and techniques that are crucial for front end interviews.

  3. In-depth solutions in JavaScript/TypeScript: Each question is accompanied by a detailed solution that not only provides the correct answer but also walks you through the thought process behind it. These solutions break down both the "how" and "why", helping you understand the most efficient ways to tackle algorithmic problems. Unlike other resources, we have solved every question in JavaScript/TypeScript, making this a reliable source of credible solutions that are specifically tailored for front end developers.

  4. Realistic coding environment: Practice coding directly in your browser with a workspace that closely simulates the conditions of real front end coding interviews. This setup allows you to get comfortable with the tools and environments you'll encounter during the actual interview process.

  5. Instant feedback with automated testing: To maximize your learning, we provide automated test cases that offer immediate feedback on your code. This instant evaluation allows you to quickly identify and correct mistakes, ensuring you're continually improving as you prepare for your front end interviews.