Software Engineer Interview Questions
Practice 4,474 real software engineer interview questions for 2026. Covers top employers like Google, Amazon, OpenAI, and Uber — real questions from actual onsites with detailed solutions — and is built for focused interview preparation. This collection emphasizes coding and algorithms first, then system design, performance, and role-specific domains so you can train the exact skills interviewers test. What’s distinctive: coding rounds still dominate at every company, Google often emphasizes algorithms and distributed-systems thinking, Amazon commonly probes scalable-services design and operational tradeoffs, OpenAI leans toward ML systems, model deployment and inference-scaling problems, and Uber typically asks real-time routing, geospatial and consistency challenges. Expect live coding, pair-programming, and whiteboard/system-design sketches. To prepare efficiently, drill medium-to-hard algorithm problems with time limits, practice end-to-end system design sketches focused on capacity and reliability, and rehearse concise behavioral stories that show ownership and impact.
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"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
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"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Choose fastest transportation mode on city grid
You live in a city modeled as a 2D grid. Each cell is either: - A transportation mode 1..4 where: - 1 = Walk, 2 = Bike, 3 = Car, 4 = Train - S = sou...
Find most frequent call path in logs
You are given a sequence of trace log lines for a single-threaded program. Each line is either a function entry or exit: - Entry: "-> funcName" - Exit...
Compute iterative sliding-window sum reduction
Problem Given an integer array nums and an integer window size k, repeatedly apply the following reduction: - If len(nums) > k: replace nums with a ne...
Decode a JWT string without libraries
Implement a function that decodes (but does not necessarily verify) a JWT token. A JWT is a string of the form: ` <base64url(header)>.<base64url(paylo...
Design dynamic weighted random sampling with updates
Problem: Support weighted random sampling with insert/delete Design a data structure that maintains a dynamic set of items, each with a positive integ...
Compute maximum later-earlier difference
You are given an integer array output (length n ≥ 1). Define the gain of choosing indices i < j as output[j] - output[i]. Return the maximum gain over...
Compute sums and maximum path in a tree
You are given a binary tree whose nodes store integer values. You must implement your own Node class (e.g., val, left, right). Task Write a function t...
Solve common interview coding problems
You are given several independent coding tasks (typical of SWE/MLE interview rounds). For each task, design an algorithm and describe the time/space c...
Design iterator for sorted union
Problem: Union Iterator for Sorted Inputs You are given two input iterators it1 and it2. Each iterator returns integers in strictly increasing order (...
How to handle huge inputs?
In a coding interview, after solving an in-memory algorithmic problem, the interviewer asks: "What would you do if the input were extremely large?" Gi...
Implement topological sort from string input
You receive N lines of raw text describing task dependencies, e.g., 'install A after B', 'C->A', 'B before D'. Implement a function that: ( 1) parses ...
Design a global notification service
Design a global notification service System Design: Globally Distributed Notification Service Context You are designing a multi-tenant notification pl...
Design an in-memory database with TTL and backups
You are asked to implement a small in-memory “database” that evolves across 4 parts. In each part you may reuse your previous code and only add/extend...
Parse chemical formula with multipliers
Parse chemical formula with multipliers Given a string representing a chemical formula, parse it and return the total count of each element. The formu...
Design a Real-Time Suggestions Service
Design a Real-Time Suggestions Service System Design: Real-Time Typeahead/Autocomplete Context Design a real-time typeahead/autocomplete service for a...
Print Sentences as Table
Implement a function that formats a list of sentences as a bordered table. Given: - sentences: a list of strings - width: the fixed content width of e...
Implement a Rollback Key-Value Store
Design and implement an in-memory key-value store that supports rollback. The store should support at least the following operations: - set(key, value...
Group employees by shared interests
Given N employees, each with an integer id and a set of interests (strings), write an algorithm to find all employees who share at least one common in...
Check if two-group seating is possible
Check if two-group seating is possible Given an undirected graph represented as an adjacency list where adj[i] lists the indices of guests who know gu...
Reconstruct a tree from two traversals
Reconstruct a tree from two traversals Given two arrays representing the preorder and inorder traversals of a binary tree with unique values, reconstr...