Nextdoor Coding & Algorithms Interview Questions

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12 Questions 1 Company08.03.2026
Showing 12 results
Role
Nextdoor logo
Nextdoor
Medium
Software Engineer

Merge Weekly Time Intervals

Implement merge_weekly_intervals(intervals). Each interval is [start_day, start_time, end_day, end_time]. Days are Mon, Tue, Wed, Thu, Fri, Sat, or Su...

Coding & Algorithms
0
0
1 people solved
Aug 3, 2026
Nextdoor logo
Nextdoor
Hard
Software Engineer Locked

Simulate Transaction Lock Scheduling

This question evaluates understanding of concurrency control, lock scheduling, transaction state management, and queuing behavior in the Coding & Algo...

Coding & Algorithms
0
0
11 people solved
May 27, 2026
Nextdoor logo
Nextdoor
Hard
Data Engineer

Write SQL for basic user metrics

You are given a simplified schema for a fictional social app called Nextagram: - users(user_id PK, username, created_at TIMESTAMP) - follows(follower_...

Coding & Algorithms
5
0
88 people solved
Feb 8, 2026
Nextdoor logo
Nextdoor
Hard
Data Engineer

Write SQL for app metrics

You are given a simplified schema for a photo-sharing app: - users(user_id, user_name, joined_at) - photos(photo_id, user_id, created_at) - follows(fo...

Coding & Algorithms
5
0
58 people solved
Mar 1, 2026
Nextdoor logo
Nextdoor
Easy
iOS Engineer Locked

Flatten Nested Comments

This question evaluates proficiency with tree traversal and hierarchical data manipulation, specifically recursion versus iterative approaches and enf...

Coding & Algorithms
3
0
52 people solved
Jan 15, 2026
Nextdoor logo
Nextdoor
Medium
Machine Learning Engineer

Implement ordering with dependency constraints

You are given n items labeled 0..n−1 and a list of precedence constraints edges[i] = [u, v] meaning u must appear before v. Return a valid ordering of...

Coding & Algorithms
12
0
97 people solved
Sep 6, 2025
Nextdoor logo
Nextdoor
Medium
Machine Learning Engineer

Implement and use a version comparator

Implement and use a version comparator You are given up to 100,000 version-like identifiers (e.g., "1.0", "01.2.0", "2.0.0-alpha", "1.10.3"). Implemen...

Coding & Algorithms
7
0
77 people solved
Jul 27, 2025
Nextdoor logo
Nextdoor
Medium
Software Engineer Locked

Group Photos and Sort Feed Items

This question evaluates proficiency in list/sequence transformation, detecting consecutive runs, grouping elements, aggregating attributes, and perfor...

Coding & Algorithms
1
0
11 people solved
May 31, 2026
Nextdoor logo
Nextdoor
Medium
Machine Learning EngineerNew Grad

Build Ranked Feed With Photo Batching

You are given a list of feed objects. Each object has: - id: a unique string - type: one of Normal, Video, or Photo - score: a numeric ranking score C...

Coding & Algorithms
1
0
15 people solved
Apr 5, 2026
Nextdoor logo
Nextdoor
Medium
Software Engineer

Merge Weekly Time Intervals

You are given a list of time intervals within a single week. Each time is written as a day-of-week plus a 24-hour clock, for example Sat 13:00 or Mon ...

Coding & Algorithms
10
0
79 people solved
Mar 16, 2026
Nextdoor logo
Nextdoor
Medium
Machine Learning Engineer

Merge overlapping weekly time intervals

You are given a list of time intervals representing meetings. Each interval is a pair of strings in the format: - "<Day> <H>:<MM>" (24-hour time) - <D...

Coding & Algorithms
12
0
96 people solved
Mar 1, 2026
Nextdoor logo
Nextdoor
Medium
Software Engineer

Implement version string comparator with extensions

Implement a function compareVersions(a, b) that compares two software version strings. Each version consists of dot-separated numeric components (e.g....

Coding & Algorithms
11
0
92 people solved
Jul 31, 2025

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