DoorDash | Senior Engineer Details about Code Craft and System Design

For doordash, the code craft interview is a bit tricky and different. But luckily it has a small question bank and I think only 2 questions so I was able to practice both of those questions on a website. That helped a lot.

Coding

Problem: Finding the nearest dasher to a location

I took a BFS approach from the start and the interviewer gave me the thumbs up to implement it.

Follow-up: Return all equidistant closest locations

Discussed:

• Handling unreachable destinations
• Multi-source BFS optimization for repeated queries

Where I did well:

• Quickly identified BFS as the right approach and implemented cleanly
• Handled the follow-up extension smoothly

Result: All the test cases passed, interviewer seemed happy.

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Code Craft

Problem: Make a payment system for dashers.

Edge cases I tried to handle:

• Overlapping delivery windows
• Multiple orders at different stages
• Time window boundaries
• Concurrent order limits

Result:

Interviewer seemed satisfied with the incremental approach and handling of edge cases.

I had practiced all the code craft problems here before so it was a lot easier for me.

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System Design

Problem: Review System with Voting

It's covered by this recently asked doordash design questions listed here: https://offerretriever.com/questions/31

Lukily I looked through and tried to practice all the design questions ahead of time, but sadly I didn't spend too long thinking about this one.

It went mostly ok, I choked a bit while talking about adding a cache, but we moved on from it and the rest went alright

Could have discussed more about sharding strategies for high-volume restaurants

Result: Feedback was mixed, felt I could have gone deeper on scalability ⚠️

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Behavioral

Standard behavioral round covering:

• Past project experiences
• Conflict resolution scenarios
• Red flag screening questions (why leaving current role, team dynamics, etc.)
• Deep dive into a challenging project

Pretty straightforward, no surprises here. Interviewer was friendly and conversational.

Result: Went smoothly ✅

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Overall Takeaways

For system design, I should have prepared in-depth for all the recently asked system design questions. My questions was on that list but so sad I didn't prepare it well even though knowing it ahead of time