Representative Design problems
Implement an efficient LRU Cache using hash table and doubly-linked list to achieve O(1) operations for get and put.
Open problem page#155 Min StackDesign a stack with O(1) operations to push, pop, retrieve the top element, and get the minimum element in constant time.
Open problem page#173 Binary Search Tree IteratorImplement an iterator for in-order traversal of a binary search tree (BST), maintaining traversal state with stack-based operations.
Open problem page#208 Implement Trie (Prefix Tree)This problem requires designing a Trie (Prefix Tree) to efficiently store and query strings using hash table concepts for fast retrieval.
Open problem page#211 Design Add and Search Words Data StructureBuild a WordDictionary supporting dynamic word addition and search with wildcard matching efficiently using Trie and DFS.
Open problem page#225 Implement Stack using QueuesThis problem tests your ability to simulate a LIFO stack using two queues while preserving all standard stack operations correctly.
Open problem page#232 Implement Queue using StacksImplement a queue using two stacks, focusing on stack-based state management to achieve FIFO behavior in a queue.
Open problem page#284 Peeking IteratorDesign an iterator with peek functionality, adding to the standard next and hasNext operations for efficient element access.
Open problem page#295 Find Median from Data StreamImplement a MedianFinder class that supports adding numbers and finding the median from a data stream.
Open problem pageDesign interview questions usually collapse into a small set of repeatable moves. This page groups those GhostInterview problem pages together so you can stay inside one pattern family, compare representative questions, and practice explanations that transfer across multiple prompts. If you are trying to sharpen one interview weakness instead of browsing the entire library, start here.
Why Design Matters In Coding Interviews
Interviewers rarely care about the label alone. They care about whether you can recognize when the Design pattern applies, explain why it applies, and avoid the failure modes that usually show up under time pressure. That is why this page focuses on the family of problems rather than a single isolated example.
Pattern families that show up here
- Array scanning plus hash lookup
- Linked-list pointer manipulation
- Binary search over the valid answer space
Use this page to narrow the session
Start from this topic hub, choose one or two representative problems, and then open the detailed problem pages only after you know which version of the pattern you want to reinforce.
How To Practice This Topic
The best workflow is to keep the prep block narrow. Pick one easy or medium problem to confirm the base pattern, then one medium or hard problem to test whether the explanation still holds when the constraints tighten. Once the logic is stable, move into GhostInterview to rehearse the live explanation flow.
Focus on transfer, not title count
Solving more Design titles is less useful than understanding how the same move changes across examples. Try to describe what stays the same and what changes from one problem to the next.
Use the problem page when you want the exact breakdown
This topic hub is the discovery layer. The single-problem pages are where you get the answer-first summary, examples, constraints, approach, complexity, pitfalls, and solver CTA.
How GhostInterview Fits
GhostInterview works best after you know which pattern family you are inside. Use this page to choose the right Design problem, then use the solver to get the answer path, complexity framing, and follow-up support without switching into a generic study flow.
FAQ
What does the Design topic usually test in interviews?
Design questions usually test whether you can spot the underlying pattern quickly, explain the trade-offs, and move from intuition to implementation without losing clarity.
How should I use this Design topic page?
Use it as a pattern hub. Start with the representative problems on this page, compare the common approach, and then open the exact problem page when you want the full breakdown.
How many GhostInterview problem pages are in the Design group?
This topic page currently groups 94 indexed GhostInterview problem pages under the Design family.
Should I practice this topic before harder patterns?
That depends on your current gaps. If Design is already a weak spot in interviews, it is usually better to stabilize it first before moving into more advanced or less frequent patterns.
Where does GhostInterview fit once I pick a Design problem?
The topic page narrows the pattern family. The problem page gives the exact breakdown. GhostInterview is the solver layer when you need direct help with execution, complexity, and follow-up handling.
Stay close to the same reasoning family
610 overlapping problems
Open topic pageArray1,672 overlapping problems
Open topic pageOrdered Set59 overlapping problems
Open topic pageString699 overlapping problems
Open topic pageHeap (Priority Queue)169 overlapping problems
Open topic pageBinary Search265 overlapping problems
Open topic pageNeed direct help once you choose a Design problem?
Use GhostInterview as the solver layer after you select the exact prompt. Capture the question, get the answer path and complexity framing, and keep the workflow inside the same topic family.