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.
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"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."
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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."
"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."
Solve string grouping and tree right-view problems
Problem 1: Group words that are anagrams You are given an array of strings words. Two strings are anagrams if they contain the same characters with th...
Solve three coding tasks from onsite
This set of tasks evaluates array-based greedy reasoning for circular route feasibility, stack-based parsing for bracket matching, and grid/graph reac...
Implement a resumable data loader
This question evaluates a candidate's ability to design stateful, resumable data iteration with deterministic shuffling and compact serializable check...
Implement type AST and infer generics
This question evaluates a candidate's ability to design an abstract syntax tree representation and implement generic type inference for a small langua...
Solve these algorithmic problems
You are given the following independent coding tasks. For each task, design an algorithm and implement a function that returns the requested output. -...
Implement a random fixed-size load balancer
Problem: Build a simple load balancer Implement a minimal in-memory load balancer that routes each incoming request to one backend node chosen uniform...
Check perfect square using binary search
Perfect Square Check (Binary Search) Given a positive integer n, determine whether it is a perfect square (i.e., there exists an integer x such that x...
Find most frequent call path in logs
This question evaluates stack-based simulation of single-threaded call traces, hierarchical path construction and frequency counting with deterministi...
Validate parent array forms a tree
Problem You are given an integer array parent of length n describing a directed parent pointer for each node i (nodes are labeled 0..n-1). - parent[i]...
Sample index from probability distribution
This question evaluates proficiency in randomized algorithms and probability-based sampling, along with algorithmic preprocessing and data-structure d...
Solve three array/string/graph coding tasks
This set of three coding tasks evaluates proficiency in fundamental data structures and algorithms, covering multi-way array merging, custom character...
Solve string and hashmap coding tasks
This multi-part prompt evaluates string manipulation, hash map usage for grouping and lookup, and simulation of sequential commands, along with robust...
Minimize Fence Painting Operations
This question evaluates algorithmic problem-solving and optimization skills, focusing on minimizing painting operations on an array-modeled fence and ...
Solve substring and access-log problems
This question evaluates proficiency in string algorithms, frequency analysis, and set/hash-based data processing by testing substring transformation u...
Determine if tree has path sum
This question evaluates understanding of binary tree data structures and traversal techniques, along with the ability to accumulate and track root-to-...
Traverse org chart level by level
This question evaluates understanding of hierarchical data modeling and tree traversal, specifically breadth-first (level-order) traversal and reconst...
Filter Invalid Data Events
This question evaluates a candidate's ability to implement data validation, deduplication, stable filtering, time-range and allow-list checks, and to ...
Implement matrix transpose and KV store
The phone screen for a Linux-oriented software engineering role included multiple coding tasks: 1. Transpose an n x n matrix Given a square matri...
Solve mixed coding tasks from interviews
Solve the following interview-style coding problems (you may choose any programming language unless specified). Provide correct logic and handle edge ...
Insert parentheses to minimize expression value
You are given a string expression of the form A+B, where A and B are non-empty strings of digits (no digit is '0'). You must insert exactly one pair o...