Top 50 design Interview Questions
The most frequently asked design questions across all roles and companies, ranked by real interview frequency. Updated daily.
Implement per-client sliding-window rate limiting using queues and timestamp expiration.
Citadel
Juspay
GoogleConvert class definitions and UML relationships into deterministic Mermaid class-diagram lines.
Palantir
Palantir technologiesImplement a padding-free packed struct with named fields, indexed access, and updates using cumulative byte offsets.
Jane StreetSimulate a countdown timer with start, pause, resume, reset, and tick commands using a finite-state model.
GoogleFlatten nested dictionaries into ordered leaf-path strings using an iterative depth-first traversal.
RedditImplement parking allocation, ticketing, availability, and exit fee APIs using heaps and hash maps.
Kotak Mahindra BankPartition a binary array in place with all 0s before all 1s using two pointers.
NiCEImplement a one-bit full adder by composing two half adders and combining their carry outputs.
QualcommFind each array's second-largest distinct value and determine whether input numbers are powers of two in PostgreSQL.
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