The question bank
249 interview questions across four rounds. Open any one to see the prompt and exactly what it's graded on.
249 questions
System design
Classic warm-up
Infra / API platform
Social / Meta-style
WhatsApp / Slack-style
Video / media
Top system design
- Design a web crawler45 min
- Design a distributed cache45 min
- Design a key-value store45 min
- Design Dropbox45 min
- Design Uber45 min
- Design Ticketmaster45 min
- Design search autocomplete45 min
- Design a distributed job scheduler45 min
- Design a payment system45 min
- Design Instagram45 min
- Design a metrics and monitoring system45 min
- Design a real-time leaderboard45 min
- Design Yelp (nearby places)45 min
- Design Google Docs45 min
- Design a unique ID generator45 min
Most-asked system design
- Design a link analytics service45 min
- Design search for a social network45 min
- Design a video streaming service45 min
- Design group chat with read receipts45 min
- Design a push notification service45 min
- Design a content delivery network45 min
- Design an ad click aggregator45 min
- Design a hotel booking system45 min
- Design a stock exchange matching engine45 min
- Design a collaborative whiteboard45 min
- Design a recommendation system45 min
- Design a centralized logging system45 min
- Design an object storage service45 min
- Design a calendar with reminders45 min
- Design price drop alerts45 min
- Design a feature flag service45 min
- Design an online coding judge45 min
- Design a parking garage system45 min
- Design an email service45 min
- Design an API gateway45 min
Coding
Big Tech favorite
Graph / BFS
Sorting
Arrays
Binary search
Two pointers
Bits
Dynamic programming
- Climbing StairsfreeEasyB7520 min
- Coin ChangeMediumB7530 min
- Longest Increasing SubsequenceMediumB7530 min
- Longest Common SubsequenceMediumB7530 min
- Word BreakMediumB7530 min
- Combination Sum IVMediumB7530 min
- House RobberMediumB7530 min
- House Robber IIMediumB7530 min
- Decode WaysMediumB7530 min
- Unique PathsMediumB7530 min
- Min Cost Climbing StairsEasy20 min
- Partition Equal Subset SumMedium30 min
- Coin Change IIMedium30 min
- Target SumMedium30 min
- Interleaving StringMedium30 min
- Longest Increasing Path in a MatrixHard40 min
- Distinct SubsequencesHard40 min
- Edit DistanceMedium30 min
- Burst BalloonsHard40 min
- Regular Expression MatchingHard40 min
- Best Time to Buy and Sell Stock with CooldownMedium30 min
Greedy
Graphs
- Clone GraphMediumB7530 min
- Course ScheduleMediumB7530 min
- Pacific Atlantic Water FlowMediumB7530 min
- Alien DictionaryHardB7540 min
- Graph Valid TreeMediumB7530 min
- Number of Connected ComponentsMediumB7530 min
- Max Area of IslandMedium30 min
- Distance to Nearest Exit (multi-source BFS)Medium30 min
- Rotting OrangesMedium30 min
- Surrounded RegionsMedium30 min
- Redundant ConnectionMedium30 min
- Word LadderHard40 min
- Course Schedule IIMedium30 min
Intervals
Linked lists
Backtracking
- Word SearchMediumB7530 min
- Generate ParenthesesMedium30 min
- SubsetsMedium30 min
- PermutationsMedium30 min
- Subsets II (with duplicates)Medium30 min
- Combination SumMedium30 min
- Combination Sum IIMedium30 min
- Palindrome PartitioningMedium30 min
- Letter Combinations of a Phone NumberMedium30 min
- N-QueensHard40 min
Sliding window
Strings
Trees
- Maximum Depth of Binary TreefreeEasyB7520 min
- Same TreeEasyB7520 min
- Invert Binary TreeEasyB7520 min
- Binary Tree Maximum Path SumHardB7540 min
- Binary Tree Level Order TraversalMediumB7530 min
- Serialize and Deserialize Binary TreeHardB7540 min
- Subtree of Another TreeEasyB7520 min
- Construct Binary Tree from Preorder and InorderMediumB7530 min
- Validate Binary Search TreeMediumB7530 min
- Kth Smallest Element in a BSTMediumB7530 min
- Lowest Common Ancestor of a BSTMediumB7530 min
- Diameter of Binary TreeEasy20 min
- Balanced Binary TreeEasy20 min
- Binary Tree Right Side ViewMedium30 min
- Count Good Nodes in Binary TreeMedium30 min