Representative Stack problems
Determine if a string of parentheses, brackets, and braces is correctly nested using a stack for proper order validation.
Open problem page#32 Longest Valid ParenthesesCompute the length of the longest well-formed parentheses substring using state transition dynamic programming and stack tracking techniques efficiently.
Open problem page#42 Trapping Rain WaterCalculate the total trapped rain water using the elevation map array, leveraging dynamic programming and two-pointer patterns efficiently.
Open problem page#71 Simplify PathSimplify a Unix-style path by transforming it into its canonical form using stack-based state management.
Open problem page#84 Largest Rectangle in HistogramFind the maximal rectangular area in a histogram using stack-based state management for precise bar tracking and width calculations.
Open problem page#85 Maximal RectangleCompute the largest rectangle of 1's in a binary matrix using dynamic programming and stack-based state transitions efficiently.
Open problem page#94 Binary Tree Inorder TraversalBinary Tree Inorder Traversal asks you to visit left subtree, node, then right subtree without losing position while moving through the tree.
Open problem page#114 Flatten Binary Tree to Linked ListFlatten a binary tree into a right-skewed linked list by manipulating pointers following a pre-order traversal, handling null nodes carefully.
Open problem page#143 Reorder ListReorder List requires careful pointer manipulation in a singly linked list to interleave nodes from the ends without altering values.
Open problem pageStack 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 Stack Matters In Coding Interviews
Interviewers rarely care about the label alone. They care about whether you can recognize when the Stack 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
- Stack-based state management
- State transition dynamic programming
- Binary-tree traversal and state tracking
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 Stack 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 Stack 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 Stack topic usually test in interviews?
Stack 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 Stack 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 Stack group?
This topic page currently groups 140 indexed GhostInterview problem pages under the Stack family.
Should I practice this topic before harder patterns?
That depends on your current gaps. If Stack 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 Stack 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
Need direct help once you choose a Stack 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.