Medium DoorDash Interview Questions: Strategy Guide

Medium questions at DoorDash form the core of their technical interviews, with 51 out of their 87 cataloged problems falling into this difficulty tier. These problems are designed to assess your ability to apply fundamental data structures and algorithms to scenarios that model real-world platform challenges. You'll need to translate a word problem into a clean, optimal solution under time pressure, demonstrating both technical competency and clear communication.

Common Patterns

DoorDash's Medium questions frequently test specific algorithmic patterns relevant to logistics, mapping, and order management. Mastering these will give you a significant advantage.

Graph Traversal (BFS/DFS) is paramount for problems involving delivery routes, network connectivity, or hierarchical data. Expect to navigate grids or adjacency lists.

# BFS for shortest path in unweighted graph
from collections import deque
def bfs_shortest_path(graph, start, end):
    queue = deque([[start]])
    visited = set([start])
    while queue:
        path = queue.popleft()
        node = path[-1]
        if node == end:
            return path
        for neighbor in graph[node]:
            if neighbor not in visited:
                visited.add(neighbor)
                queue.append(path + [neighbor])
    return []

Array/String Manipulation questions often simulate processing order batches, logs, or time series data, requiring efficient in-place operations or sliding window techniques.

Hash Maps for Frequency Counting are ubiquitous for problems involving order tracking, deduplication, or resource allocation, where O(1) lookups are critical.

Time Targets

In a standard 45-60 minute interview, you will typically be expected to solve one Medium problem, or possibly two if they are simpler. Your target breakdown should be:

• First 5-10 minutes: Clarify requirements, ask edge case questions, and verbally outline your approach.
• Next 15-20 minutes: Write clean, syntactically correct code. Prioritize getting a working solution over premature optimization, but keep efficiency in mind from the start.
• Final 5-10 minutes: Walk through your code with a test case, discuss time/space complexity, and mention potential optimizations or follow-ups. The ability to finish and communicate clearly is often as important as raw speed.

Practice Strategy

Do not simply solve problems sequentially. Use the 51 Medium questions strategically:

1. Pattern-First Practice: Group problems by the patterns above. Solve all graph problems in a row, then all array problems. This builds deep muscle memory.
2. Simulate Interview Conditions: Always set a 25-minute timer when you practice. Write code on a whiteboard or in a plain editor without auto-complete.
3. Prioritize Recent & Frequent Questions: DoorDash's question list evolves. Focus your initial efforts on problems that have appeared most often in the last year.
4. Verbally Articulate Your Steps: After solving, explain your solution out loud as if to an interviewer. This solidifies your understanding and improves communication.

Practice Medium DoorDash questions