DoorDash backend engineer interviews typically focus on APIs, databases, system design, concurrency, caching, and data structures.
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system design
Hard
Verified Question
#1
1. Top 8 Doordash System Design Questions Jan 2026
Category: Linked list system design problem
System Design Questions - DoorDash These are the commonly asked system design questions from DoorDash interviews. Updated January 2026.
Input: Linked listOutput: Computed result
coding
Medium
Verified Question
#2
2. Code Craft - Bootstrap API
Category: String coding problem
Question You are tasked with implementing a Bootstrap API that aggregates data from multiple services for a given user. Given a userId, you...
Output: Computed result
coding
Hard
Verified Question
#3
3. Code Craft - Driver Payment System
Category: Algorithm coding problem
Question You are in charge of implementing the Dasher payment model. Given the sequence of accepted/fulfilled order activities from a given dasher...
Input: ListOutput: Computed result
coding
Medium
Verified Question
#4
4. Find Closest Dasher
Category: Algorithm coding problem
Question You are given an m × n board representing a delivery area. The board contains: - 'X' - blockers (obstacles) - 'D' - DashMarts...
Output: Integer
coding
Medium
Verified Question
#5
5. Find Menu Changes
Category: Tree coding problem
Question You are given two tree structures representing an old menu and a new menu. Each tree node has: - key: identifier for the menu...
Output: Computed result
coding
Medium
Verified Question
#6
6. Location Index
Category: Graph coding problemImplement a
LocationIndex class that stores a set of named points on a 2D grid. The constructor takes three arrays: names (list of location name...Input: 2D gridOutput: Computed result
coding
Medium
Verified Question
#7
7. Covered Service Zones
Category: Algorithm coding problemYou are given two binary
m x n matrices: coverage and demand. A cell in demand is active if its value is 1. Active cells that are...Input: Number(s)Output: Integer
coding
Hard
Verified Question
#8
8. Wildcard Segment Counter
Category: String coding problemYou are given a
template string consisting only of the characters '0', '1', and '?', and a list of integers run_lengths. A '?' in the...Input: Array of integersOutput: Computed result
coding
Medium
Verified Question
#9
9. Peak Value Processing Order
Category: Algorithm coding problemYou are given a list of unique integers
values. At each step, identify all eligible values: a value is eligible if it is strictly greater than...Input: ListOutput: Computed result
coding
Hard
Verified Question
#10
10. Directory Registry
Category: Tree coding problemImplement a
DirectoryRegistry class that manages a hierarchical key-value store modeled as a tree of paths. The root path "/" always exists with...Input: StringOutput: Computed result
coding
Hard
Verified Question
#11
11. Ride Earnings Calculator
Category: String coding problemYou are given
records, a list of ride events. Each record is a list of three strings: [ride_id, timestamp, status]. Possible statuses are...Input: ListOutput: Computed result
coding
Medium
Verified Question
#12
12. Meeting Slot Generator
Category: Interval-based coding problemGiven a
start time and an end time, generate all meeting check-in slots at 5-minute intervals after start up to and including end. The...Input: ListOutput: Computed result
coding
Medium
Verified Question
#13
13. Catalog Tree Diff Counter
Category: Tree coding problemYou are given two n-ary trees representing an old and a new version of a product catalog. Each node in the tree has the following fields: -
key...Input: ListOutput: Computed result
coding
Hard
graph
#1
1. [OA] Graph Traversal — optimize DoorDash's restaurant selection algorithm
DoorDash needs to determine the most popular restaurants within a geographical area. To accomplish this, a graph traversal algorithm can be applied to search for the connected components in the restaurant delivery network.
Using
Function Signature:
Input:
Output:
Explanation: There are two connected components: {0, 1, 2} and {3, 4}. Constraints:
Using
n restaurants where each restaurant is a node connected by edges (deliverable routes), write a function that returns the number of connected components in the graph representing the available restaurants.Function Signature:
def count_connected_components(n: int, edges: List[Tuple[int, int]]) -> int: - Returns the number of connected components in the given graph.Example 1: Input:
n = 5, edges = [(0, 1), (1, 2), (3, 4)] Output:
2 Explanation: There are two connected components: {0, 1, 2} and {3, 4}. Constraints:
1 <= n <= 10^40 <= len(edges) <= n*(n-1)/2
coding
Hard
sliding window
#2
2. [OA] Sliding Window — optimize the order delivery window for DoorDash's logistics
In order to maximize delivery efficiency, DoorDash needs to determine the optimal delivery window for a set of orders. By using a sliding window technique, we can minimize the time taken to deliver all orders without exceeding a certain capacity.
Given an array of
Function Signature:
Input:
Output:
Explanation: Orders (1, 4), (2, 6), and (3, 8) can be delivered within the time limit. Constraints:
Given an array of
orders where each order contains the pickup_time and delivery_time, return the maximum number of orders that can be delivered within a given time_limit.Function Signature:
def max_orders(orders: List[Tuple[int, int]], time_limit: int) -> int: - Returns the maximum number of orders that can be fulfilled within the given time limit.Example 1: Input:
orders = [(1, 4), (2, 6), (3, 8), (5, 10)], time_limit = 8 Output:
3 Explanation: Orders (1, 4), (2, 6), and (3, 8) can be delivered within the time limit. Constraints:
1 <= len(orders) <= 10^50 <= pickup_time < delivery_time <= 10^60 <= time_limit <= 10^6
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