Coding & Algorithms Interview Questions
Practice 3,013 real Coding & Algorithms interview questions for 2026. Coding & Algorithms interview questions for top tech firms like Meta, Amazon, Google, Uber, and TikTok — real questions from actual interviews with detailed solutions — to power your interview preparation. This collection is sharply focused on algorithmic patterns (arrays, strings, sliding windows, trees/graphs, dynamic programming, greedy, two-pointers, and hashing), clean, review-ready code, and the explanation skills that distinguish hires. In 2026 expect familiar medium-to-hard problems plus newer twists: AI-enabled or multi-file coding rounds at some companies, more emphasis on explainability and edge-case reasoning, and occasional real-world performance constraints (streaming, concurrency, memory limits). Interviewers evaluate problem framing, algorithm choice, complexity trade-offs, test-case thinking, and communication under time pressure. Best prep mixes pattern-based practice, timed mock interviews, code-review style polishing, and rehearsed explanations of complexity and tradeoffs. Focus your last-mile prep on writing correct, readable code quickly and on explaining why your solution is robust and efficient for production scenarios.
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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 honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"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."
Implement Multi-Head Attention from Scratch in NumPy
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Find the Most Common Visit Pattern
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Compute effective permissions on DAG and prune tree
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Implement a random fixed-size load balancer
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Rearrange Tasks With Cooldown
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Remove duplicates and find constrained longest subsequence
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Generate Data Labeling Schedules
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Design a Tic-Tac-Toe Engine
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Implement a Spreadsheet With Formulas
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Minimize Travel Assignment Cost
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Implement a thread-safe money transfer
Problem: Implement a concurrent-safe transfer function You are given an in-memory store of bank accounts: - Each account has an accountId and a balanc...
Count subarrays with sum equals k
Given an integer array nums (may contain negative numbers and zeros) and an integer k, return the number of contiguous subarrays whose sum is exactly ...
Highest Salary Using Java Streams
Highest Salary Using Java Streams You are given a list of Employee objects. Each Employee is a plain Java object (POJO) with the following fields: `ja...
Implement a simplified memcached server
Implement a simplified in-memory key-value store that speaks a small text protocol inspired by memcached. The server stores keys and raw byte values i...
Implement lexicographically smallest Two Sum
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Determine If One Binary Tree Is a Substructure of Another
Given two binary trees A and B, determine whether B is a substructure of A. B is a substructure of A if there exists some node in A such that the subt...