Interview Prep
Algorithm interview questions and how to answer them
Algorithm interviews reward pattern recognition. Once you've seen dynamic programming or binary search show up enough times in different shapes, you can spot them quickly. These questions cover the patterns that appear most.
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Algorithm interview questions and how to answer them
How would you coach candidates to approach recursive interview problems?
Function contract. Base cases. Recursive state. Trace small example
What are the base case and recursive case in a recursive function?
Base case stops. Recursive case reduces. Must make progress. Simplest input handled directly
How do you use a hash map for frequency counting?
Key is item. Value is count. O(n) expected time. O(k) space
How should senior engineers evaluate heap usage in code review?
Priority definition. Comparator direction. Metadata and stale entries. Heap size in complexity
How does a linear search work and what is its time complexity?
O(n) worst case. O(1) best case. works on unsorted data. no preprocessing needed
How does binary search work and what are its requirements?
O(log n) time. requires sorted array. requires random access. off-by-one errors are the main bug
How do you merge K sorted lists using a heap?
Heap holds one item per list. Extract smallest. Push next from same list. O(N log K)
What are common priority queue use cases?
Process by priority. Dijkstra. Event simulation. Scheduling and top-K
How would you choose between a stack and a queue for a problem?
Stacks use last-in-first-out ordering. Queues use first-in-first-out ordering. Problem requirements determine the choice. Undo features suit stacks. Scheduling tasks often suits queues
How do you implement a circular queue?
Fixed-size ring buffer. head and tail indexes. Modulo wraparound. size distinguishes full and empty
Common mistakes
- Coding before talking through the approach
- Skipping the obvious brute force first
- Not handling the edge cases
What interviewers weigh
- Recognizing the underlying pattern
- How you optimize from a brute force start
- Whether you test your own solution