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Mock interviews provide you with a way to test your abilities in a timed setting, just like a coding challenge or on-site interview. You choose the company and we will select an appropriate question from our constantly growing database.

Find out which questions turn up most frequently in interviews so that you know where to focus your personal studying. Invaluable data collected from thousands of samples.

Gain exclusive access to our latest and ever-growing collection of premium content, such as questions, Explore cards, and premium solutions, where detailed explanations are written by our team of algorithm and data structure experts.

Target your studying more accurately towards your dream job. Find out which companies asked which questions, we have nearly 200 questions from Google alone.

- Find the Start and End Number of Continuous Ranges
- Students and Examinations
- Traffic Light Controlled Intersection
- All People Report to the Given Manager
- Print Immutable Linked List in Reverse
- Page Recommendations
- Average Selling Price
- Web Crawler Multithreaded
- Number of Comments per Post
- Web Crawler
- Report Contiguous Dates
- Team Scores in Football Tournament
- Queries Quality and Percentage
- Monthly Transactions II
- Last Person to Fit in the Elevator
- Tournament Winners
- Monthly Transactions I
- Design Bounded Blocking Queue
- Immediate Food Delivery II
- Immediate Food Delivery I
- Diet Plan Performance
- Product Price at a Given Date
- Market Analysis II
- Market Analysis I
- Article Views II
- Article Views I
- User Activity for the Past 30 Days II
- User Activity for the Past 30 Days I
- Reported Posts II
- Number of Ships in a Rectangle
- User Purchase Platform
- Active Businesses
- Reported Posts
- Highest Grade For Each Student
- Handshakes That Don't Cross
- New Users Daily Count
- Palindrome Removal
- Delete Tree Nodes
- Remove Interval
- Hexspeak
- Unpopular Books
- Game Play Analysis V
- Divide Chocolate
- Synonymous Sentences
- Smallest Common Region
- Encode Number
- Game Play Analysis IV
- Game Play Analysis III
- Game Play Analysis II
- Game Play Analysis I
- Valid Palindrome III
- Tree Diameter
- Design A Leaderboard
- Array Transformation
- Sales Analysis III
- Sales Analysis II
- Sales Analysis I
- Minimum Time to Build Blocks
- Toss Strange Coins
- Meeting Scheduler
- Missing Number In Arithmetic Progression
- Project Employees III
- Project Employees II
- Project Employees I
- Product Sales Analysis III
- Product Sales Analysis II
- Product Sales Analysis I
- Lexicographically Smallest Equivalent String
- Number of Valid Subarrays
- Longest Repeating Substring
- Missing Element in Sorted Array
- All Paths from Source Lead to Destination
- Confusing Number
- Minimize Rounding Error to Meet Target
- Campus Bikes
- Shortest Way to Form String
- Maximum Number of Ones
- Stepping Numbers
- Two Sum BSTs
- Intersection of Three Sorted Arrays
- Optimize Water Distribution in a Village
- Find Smallest Common Element in All Rows
- Minimum Knight Moves
- How Many Apples Can You Put into the Basket
- Actors and Directors Who Cooperated At Least Three Times
- Customers Who Bought All Products
- Shortest Distance to Target Color
- Before and After Puzzle
- Count Substrings with Only One Distinct Letter
- Minimum Cost to Connect Sticks
- Design File System
- String Transforms Into Another String
- Single-Row Keyboard
- Divide Array Into Increasing Sequences
- Analyze User Website Visit Pattern
- Minimum Swaps to Group All 1's Together
- Check If a Number Is Majority Element in a Sorted Array
- Parallel Courses
- Connecting Cities With Minimum Cost
- Path With Maximum Minimum Value
- Largest Unique Number
- Maximum Average Subtree
- Armstrong Number
- Remove Vowels from a String
- Number of Days in a Month
- The Earliest Moment When Everyone Become Friends
- Find K-Length Substrings With No Repeated Characters
- Two Sum Less Than K
- Sum of Digits in the Minimum Number
- Confusing Number II
- Brace Expansion
- Index Pairs of a String
- High Five
- Digit Count in Range
- Campus Bikes II
- Fixed Point
- Robot Room Cleaner
- Insert into a Sorted Circular Linked List
- Similar RGB Color
- Split BST
- Minimize Max Distance to Gas Station
- Search in a Sorted Array of Unknown Size
- Basic Calculator III
- Encode N-ary Tree to Binary Tree
- Serialize and Deserialize N-ary Tree
- Find Anagram Mappings
- Employee Free Time
- Bold Words in String
- Convert Binary Search Tree to Sorted Doubly Linked List
- Pour Water
- IP to CIDR
- Number Of Corner Rectangles
- Closest Leaf in a Binary Tree
- Sentence Similarity II
- Sentence Similarity
- Minimum Window Subsequence
- Max Stack
- Candy Crush
- Number of Distinct Islands II
- Number of Distinct Islands
- Next Closest Time
- K Empty Slots
- Path Sum IV
- Equal Tree Partition
- Remove 9
- Coin Path
- 4 Keys Keyboard
- Design Search Autocomplete System
- Maximum Average Subarray II
- Find the Derangement of An Array
- Design Log Storage System
- Design Excel Sum Formula
- Maximum Distance in Arrays
- Minimum Factorization
- Add Bold Tag in String
- Design Compressed String Iterator
- Biggest Single Number
- Students Report By Geography
- Average Salary: Departments VS Company
- Second Degree Follower
- Shortest Distance in a Line
- Shortest Distance in a Plane
- Triangle Judgement
- Tree Node
- Sales Person
- Consecutive Available Seats
- Friend Requests II: Who Has the Most Friends
- Design In-Memory File System
- Friend Requests I: Overall Acceptance Rate
- Kill Process
- Customer Placing the Largest Number of Orders
- Investments in 2016
- Find Customer Referee
- Count Student Number in Departments
- Find Cumulative Salary of an Employee
- Get Highest Answer Rate Question
- Squirrel Simulation
- Employee Bonus
- Winning Candidate
- Maximum Vacation Days
- Find Median Given Frequency of Numbers
- Managers with at Least 5 Direct Reports
- Median Employee Salary
- Longest Line of Consecutive One in Matrix
- Split Concatenated Strings
- Binary Tree Longest Consecutive Sequence II
- Split Array with Equal Sum
- Boundary of Binary Tree
- Output Contest Matches
- Construct Binary Tree from String
- Lonely Pixel II
- Lonely Pixel I
- Word Abbreviation
- Inorder Successor in BST II
- The Maze II
- The Maze III
- The Maze
- Max Consecutive Ones II
- Find Permutation
- Encode String with Shortest Length
- Convex Polygon
- Optimal Account Balancing
- Sequence Reconstruction
- Ternary Expression Parser
- Word Squares
- Valid Word Square
- Sentence Screen Fitting
- Minimum Unique Word Abbreviation
- Valid Word Abbreviation
- Design Phone Directory
- Range Addition
- Plus One Linked List
- Find Leaves of Binary Tree
- Nested List Weight Sum II
- Design Hit Counter
- Bomb Enemy
- Sort Transformed Array
- Logger Rate Limiter
- Rearrange String k Distance Apart
- Line Reflection
- Design Snake Game
- Android Unlock Patterns
- Design Tic-Tac-Toe
- Moving Average from Data Stream
- Longest Substring with At Most K Distinct Characters
- Nested List Weight Sum
- Largest BST Subtree
- Maximum Size Subarray Sum Equals k
- Number of Connected Components in an Undirected Graph
- Generalized Abbreviation
- Shortest Distance from All Buildings
- Binary Tree Vertical Order Traversal
- Sparse Matrix Multiplication
- Range Sum Query 2D - Mutable
- Number of Islands II
- Smallest Rectangle Enclosing Black Pixels
- Binary Tree Longest Consecutive Sequence
- Best Meeting Point
- Flip Game II
- Flip Game
- Word Pattern II
- Unique Word Abbreviation
- Walls and Gates
- Inorder Successor in BST
- Zigzag Iterator
- Wiggle Sort
- Find the Celebrity
- Paint Fence
- Closest Binary Search Tree Value II
- Encode and Decode Strings
- Closest Binary Search Tree Value
- Alien Dictionary
- Palindrome Permutation II
- Palindrome Permutation
- Paint House II
- Graph Valid Tree
- 3Sum Smaller
- Paint House
- Verify Preorder Sequence in Binary Search Tree
- Factor Combinations
- Meeting Rooms II
- Meeting Rooms
- Flatten 2D Vector
- Count Univalue Subtrees
- Group Shifted Strings
- Strobogrammatic Number III
- Strobogrammatic Number II
- Strobogrammatic Number
- Shortest Word Distance III
- Shortest Word Distance II
- Shortest Word Distance
- Reverse Words in a String II
- Two Sum III - Data structure design
- Missing Ranges
- One Edit Distance
- Longest Substring with At Most Two Distinct Characters
- Read N Characters Given Read4 II - Call multiple times
- Read N Characters Given Read4
- Binary Tree Upside Down

What will I get with a premium subscription?

In addition to free questions / articles, you will have access to exclusive premium questions / articles as well. You will also be able to group questions by company, and practice mock interviews targeting a specific company.

What are the premium articles? Is there a sample I can look at?

Some of the articles are reserved for premium subscribers only. You can take a look at this free sample article here. Please note that we are adding more articles so please check back frequently.

How does grouping questions by company work?

We compile the list of questions asked by specific companies based on data from user surveys: "*Have you met this question in a real interview?*".
These lists will be kept up to date frequently with the ever growing survey data. You can find the list of companies in the problem list page, just below the Tag lists.

What about all the existing questions?

You will continue to have access to it all, it isn't going anywhere.

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What are the premium questions? Show

Here is the current up to date premium question list, more is coming...