DoorDash Coding Interview: What They Test

Two of DoorDash's coding rounds hand you working software rather than a blank algorithm. Code Craft gives you a real business module to finish: a Premium question with peak-hour multipliers, or a cart that applies promotions in the right order before it shows a total. The Debugging round drops you into an unfamiliar service with failing tests and asks you to find the fault and fix it cleanly. Both grade production judgment, not algorithm recall, and together they carry about half the coding signal. So drill the algorithmic half too, by all means. It is narrower than the reputation suggests, and it is only half the job.

In the algorithmic half, one archetype towers over everything else: a multi-source grid BFS, posed as the distance from every city block to the nearest open DashMart through blocked roads. That single shape covers a Premium question, 01 Matrix, and Shortest Distance from All Buildings, and it is the highest-yield thing you can drill for this loop. Close behind it sits a weighted scheduling DP that DoorDash frames as Dasher Max Profit. A dasher picks non-overlapping deliveries with start, end, and pay to maximize earnings. Set the logistics story aside and it is a Premium question. Learn those two cold and you have the spine of the algorithm rounds.

The DoorDash angle

One shape recurs more than any other: the multi-source grid BFS. Drill it until your hands write it on their own. The naive instinct is to run a separate BFS from each cell, which blows up the moment the grid is large or the queries batch up. Seed the queue with every source at once instead, and a single sweep fills the whole grid. Passing answer versus timeout, decided right there. The follow-up almost always pushes on volume: many queries, streaming updates, a new blocked-road rule. Practice the version with obstacles and batched lookups. The textbook flood-fill only gets you partway.

The difficulty tier sits where that center of gravity suggests: medium-centered, with a grid and scheduling Hard spike rather than a Hard gauntlet. The genuinely hard items are grid Hards like a Premium question in a Matrix and the Job-Scheduling DP. No exotic graph theory. That makes the routing reputation worth a closer look before you spend prep hours on it.

The DoorDash angle

The Dijkstra reputation is mostly smoke. DoorDash's logistics framing makes weighted shortest-path sound inevitable, and you will find Dijkstra on plenty of "expected algorithms" lists for the company. It rarely lands. What actually recurs is unweighted grid BFS; a named weighted-routing problem almost never appears. Know Dijkstra well enough to talk through a weighted follow-up, then pour your hours into the BFS and DP archetypes that genuinely show up. The routing problem the reputation promises mostly doesn't.

The OA and the AI-assisted session

Two parts of the loop sit outside the standard onsite and are worth placing before you prep, starting with the online assessment. For new-grad and early-career pipelines, a HackerRank OA gates the loop, commonly two medium problems in roughly 90 minutes, occasionally with a short SQL question alongside. Experienced ICs usually skip it and go straight to a live screen. If you are early-career, the OA is your real filter, and the arrays, strings, and binary-search-on-answer layer is what it draws from, so weight that lesson accordingly.

The second is newer and less settled, so weigh it as a heads-up rather than a fixture. Over 2025 DoorDash began rolling out an AI-assisted working session. You build a feature on your own machine with a real AI agent in your editor (Cursor, Claude Code or Copilot) while the interviewer watches how you direct and verify it. DoorDash builds the round around a sharp contrast. AI is welcome in that one session and banned in every other round, where only plain autocomplete is allowed. What it measures is whether you can steer a tool through edit and debug without losing the thread. It appears to roll out unevenly from team to team, so prepare for it without assuming your loop includes it. The dedicated lesson works the format end to end.

What the rounds favor

DoorDash keeps the components of a normal loop and then tilts them toward production realism. Grids and graphs are the largest algorithmic family, carried by the multi-source BFS archetype and a grid-Hard spike from a Premium question in a Matrix. Trees and the design-coding hybrid sit next, with a Premium question the single most-reported problem candidates mention and a Premium question recurring through a Trie. Scheduling and interval DP form their own band around Dasher Max Profit. Arrays and strings hold up the OA and the warm-ups, with binary-search-on-answer close behind. Set apart from all of it is the practical band, Code Craft and Debugging, which carries no LeetCode frequency yet eats two of your onsite seats. DoorDash doesn't publish a breakdown; the split below is ordered by how often each family actually comes up.

Read the chart as where your first hours go. Grids lead the algorithm work and deserve the most reps. The practical band runs a close second and is the part a pure LeetCode grind ignores entirely, which is exactly why strong algorithm coders get surprised here. Everything else is standard patterns wearing DoorDash's logistics framing. The six lessons in this section follow that shape. Each opens with how DoorDash frames the family and the variants it favors, then works the most recurring problems end to end with the follow-up the interviewer layers on. Where a lesson leans on a base data structure, the full build lives in the free Foundations course so these pages stay on what is specifically DoorDash.

The DoorDash angle

In Code Craft, the mess is the grade. Business rules arrive tangled on purpose: refunds that can be partial, payouts with peak-hour multipliers stacked on base and tips, promotions that only apply in a certain order. Can you model that mess with clean interfaces and back the awkward inputs with tests instead of optimism? Get the main path running first, then layer the edge cases and prove each one. A working module with three tested edge cases beats a clever half-finished abstraction every time, and the Code Craft and Debugging lesson drills exactly that rhythm.

How these lessons are organized

The six lessons run from the largest algorithmic family down to the rounds that are DoorDash's own. Start with grids, the highest-yield cluster, then work through the patterns toward the practical and AI rounds that no pattern list captures.