DoorDash Coding Interview Questions
32 DoorDash coding interview problems with full optimal solutions — 3 easy, 21 medium, 8 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an DoorDash interviewer values, and a FAQ section.
Showing 3 problems of 32
- #21easyfoundational
21. Number of Islands
Count connected land zones in a grid — Doordash uses this BFS/DFS classic to see if you can reason about delivery coverage zones and autonomous map-segmentation logic under time pressure.
- #22easyfrequently asked
22. Merge Intervals
Collapse a pile of possibly-overlapping intervals into the minimal set of disjoint spans — the canonical sort-then-sweep greedy, and one of the most practically-loaded easies in the catalog. DoorDash candidates report it with the scheduling flavor played straight: delivery time windows and Dasher shift blocks ARE interval merges, and the interview's real currency is naming the pattern (sort by start, then one linear pass extending or appending) before any code appears.
- #23easyfoundational
23. Valid Parentheses
Validate bracket nesting with a stack — Doordash treats this as a warmup for stack reasoning, which surfaces in their order-processing pipeline and nested-menu parsing logic.
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