10 DRW Software Engineer (New Grad) Interview Questions (2026)

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STAR. Pick a real instance — code review, pair programming, mentorship. Walk through: the situation, what you did, how the teammate responded, the outcome. DRW values collaborative culture — show you can teach without condescension.

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Specific reasons: diverse trading firm with engineering challenges across asset classes (equities, crypto, fixed income), collegial Chicago culture, broad tech work including infrastructure, trading systems, and recently crypto/DeFi. Reference DRW's expansion into crypto (Cumberland) if relevant. Avoid 'high pay' as the lead.

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Sliding window with hash map of last-seen indices. Expand right; if character seen and last-seen ≥ left, move left to last-seen + 1. Update max length. O(n) time, O(min(n,k)) space. Walk through example. Edge cases: empty string, all-unique, all-same.

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Max-heap of size k by distance^2. Iterate points; push, then pop if size > k. O(n log k) time, O(k) space. Discuss alternative quickselect approach for O(n) average. Walk through example. Mention that comparing distance^2 avoids sqrt.

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Two stacks: main stack and min-stack. On push: push to main; push min(value, top of min-stack) to min-stack. On pop: pop from both. GetMin: return top of min-stack. O(1) operations, O(n) space. Alternative: store (value, current_min) pairs in one stack. Walk through example.

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Unweighted graph: BFS from source, track parent pointers, reconstruct path. O(V + E). Weighted positive: Dijkstra with priority queue. O((V+E) log V). Weighted with negatives: Bellman-Ford, O(V·E). Walk through one approach. Discuss when each fits.

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Mutex: thread blocks (goes to sleep) if lock is held. Context switch overhead, but no CPU waste. Spinlock: thread spins in busy-wait loop until lock is free. No context switch, but burns CPU. Use spinlock when critical section is short (< context switch cost) and contention is rare. Use mutex for longer critical sections. In trading, spinlocks are common in hot paths where context switches are unacceptable.

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Start with small congestion window (cwnd = 1 or few segments). Double cwnd per RTT until threshold. Then switch to congestion avoidance (linear growth). On packet loss, cut cwnd. Why it matters in trading: TCP connections have warmup; UDP is preferred for market data and trade execution to avoid this. Discuss alternatives (QUIC, kernel-bypass) for ultra-low latency.

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Resource Acquisition Is Initialization: tie resource lifetime to object lifetime. Acquire resource in constructor, release in destructor. Example: std::unique_ptr automatically frees memory when out of scope. Why it matters: exception safety (destructor runs even if exception thrown), no leaks. Contrast with C-style explicit malloc/free or new/delete which require manual cleanup.

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Layered: (1) Receive via UDP multicast from exchange. (2) Parse with zero-copy in hot path. (3) Distribute via lock-free ring buffers or shared memory to consumer processes. (4) Backpressure handling — drop policy for slow consumers. Discuss why latency matters at each layer; cumulative goal ~10us. Discuss tradeoffs: throughput vs latency, exactly-once vs at-least-once semantics.