Coding & Algorithms Interview Questions
Practice 3,469 real Coding & Algorithms interview questions for 2026. Covers companies like Meta, Amazon, Google, Uber, and Microsoft. Real questions from actual interviews with detailed solutions — ideal for focused interview preparation. Coding & Algorithms interview questions are the single most common technical gate for software engineering roles and are used to evaluate problem framing, algorithm selection, complexity trade-offs, correctness, edge-case reasoning, and clear communication under time pressure. Expect this category to appear in early technical screens and repeatedly across onsite loops at companies that weight it heavily (notably Meta, Google, and Amazon). Interviews will test arrays and strings, trees and graphs, dynamic programming, hashing and two‑pointer techniques, and the candidate’s ability to test and optimize code in a shared editor. Prepare with timed mock interviews, practice in the same editor you’ll use live, and build a progressive schedule that moves from fundamentals to medium/hard problems; typical candidates invest several weeks to a few months of focused practice depending on seniority and target company.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
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"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"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."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"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 several OA simulation problems
Reconstruct and solve the following coding problems from an online assessment. 1. Case-insensitive adjacent differences Given a string s, treat u...
Implement a memory allocator with malloc/free
Problem You are implementing a simplified memory allocator over a contiguous memory region. Initialize the allocator with a fixed total size: - alloca...
Add Two Signed Decimal Character Arrays
Add Two Signed Decimal Character Arrays Add two signed decimal integers supplied as strings without converting the complete inputs to built-in integer...
Infection Spread Time on a Grid
Infection Spread Time on a Grid You are given an m x n grid where every cell holds one of three integer values: - 0 — an empty cell that can never be ...
Decode an encoded string
Implement a decoder for an encoded string where repetition is expressed with a number followed by a bracketed substring. Rules: - A pattern k[substrin...
Solve Two OA Algorithm Problems
These problems evaluate algorithmic optimization and graph connectivity competencies, specifically cost-constrained integer resource allocation for th...
Implement rotating homepage title selector
This question evaluates understanding of data structures and algorithms for prioritized selection with stateful constraints, focusing on maintaining d...
Implement an in-memory database with TTL and backup
In-Memory Database (Levels 1–4: TTL and Backup/Restore) Implement an in-memory database that stores records identified by a string key. Each record co...
Validate whether brackets are properly nested
This question evaluates proficiency in sequence validation, paired-token matching, and the use of data structures to manage nested elements within str...
Rotate a 3×3 digit grid by 180°
This question evaluates understanding of grid and string manipulation, coordinate transformations, spatial reasoning, and character validation in cons...
Validate CSV rows under multiple verification rules
This question evaluates skills in CSV parsing, string normalization and multi-rule data validation, covering whitespace handling, length checks, case-...
Return Binary Tree Nodes in Vertical Order
Return Binary Tree Nodes in Vertical Order A binary tree has nodes numbered from 0 through n - 1, with node 0 as the root. Arrays left and right conta...
Implement Depth-First Search Traversal
This question evaluates implementation and conceptual understanding of graph traversal algorithms, specifically depth-first search on adjacency-list r...
Return right and left side views of a tree
This question evaluates understanding of binary tree data structures and the competency to identify side views by reasoning about which node is visibl...
Maximize area between vertical lines
This question evaluates algorithmic reasoning with arrays and the ability to optimize pairwise measurements, specifically assessing understanding of h...
Implement Validation and String Compression
This question evaluates string processing, input validation, tokenization, hierarchical string manipulation, and algorithmic complexity analysis skill...
Count ways to make change (DP)
This question evaluates understanding of dynamic programming and combinatorial counting, focusing on unbounded coin usage and counting order‑independe...
Compute exclusive CPU time from nested logs
You are given logs from a single-threaded CPU that runs n functions (IDs 0 to n-1). Each log entry is a string in the format: - "functionId:start:time...
Debug a PyTorch U-Net shape mismatch
This question evaluates proficiency in PyTorch model implementation, convolutional output shape arithmetic, channel configuration, and debugging of U-...
Sample a string by real-valued scores
This question evaluates probabilistic sampling, numerical stability, and algorithmic implementation skills for weighted selection under floating-point...