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."
Count Clusters of 2D Points Within a Radius
This question tests graph traversal skills, specifically identifying connected components among a set of 2D points using distance-based adjacency. It ...
Implement Multi-Head Attention from Scratch in NumPy
This coding question tests a machine learning engineer's understanding of Transformer internals by requiring a from-scratch NumPy implementation of mu...
Minimize Cost for Feature-Capable Models
This question evaluates algorithmic problem-solving and combinatorial optimization skills related to selecting cost-minimal subsets that satisfy dual ...
Minimum Sum of Weekly Maximum Costs
This question tests dynamic programming skills applied to array partitioning, specifically minimizing an objective function over contiguous subarrays....
Caesar Cipher with Translation-Table Optimization
This question tests practical string manipulation and modular arithmetic by requiring implementation of a classic Caesar cipher with correct case-pres...
Highest Average-Salary Team in an Org Chart
This question evaluates a candidate's ability to traverse tree-structured data and perform subtree aggregation, applying recursive or bottom-up DFS te...
Merge Overlapping Time Ranges
This question evaluates a candidate's ability to work with interval merging, a core array and sorting problem in technical interviews. It tests unders...
Course Prerequisite Feasibility
This question tests graph theory fundamentals, specifically cycle detection in directed graphs as modeled by dependency constraints. It evaluates prac...
Determine Whether an Undirected Graph Is 3-Colorable
Determine whether a possibly disconnected undirected graph with up to 20 vertices can be colored using at most three colors so that adjacent vertices ...
Spreadsheet Formula Engine with Cycle Detection
This question evaluates a candidate's ability to design a stateful data structure that models dependency relationships and lazily propagates updates, ...
Find the Longest Path of Equal-Valued Tree Nodes
Find the longest path of equal-valued nodes in a binary tree encoded as a breadth-first list. Clarify the ambiguity with strict BST terminology, then ...
Repeatedly Remove Adjacent Equal Characters
This question evaluates a candidate's ability to use a stack-based approach to repeatedly cancel out adjacent equal elements in a string. It tests und...
Alternate Odd and Even Numbers with Two Threads
This question evaluates a candidate's understanding of multithreading and synchronization primitives such as locks and condition variables. It tests t...
Knight Dialer: Count Dialable Digit Sequences
This question evaluates a candidate's ability to model constrained state transitions with dynamic programming, using a knight's legal moves on a phone...
Dot Product of Two Vectors (Dense, then Sparse)
This question assesses proficiency in array manipulation and algorithmic efficiency by asking for a vector dot product, first over dense arrays and th...
Inventory Allocation by Bid Priority
This question assesses simulation and priority-queue design skills, requiring careful implementation of tiered, round-robin resource allocation under ...
Optimal Commute: Nearest Transit Distance in a City Grid
This question evaluates a candidate's ability to apply multi-source breadth-first search to a grid-based shortest-path problem. It tests graph travers...
Most Active Users in a Live Communication Stream
This question tests practical application of hash-based data structures and stream processing to track and rank user activity with deduplication logic...
Print the File System State
This question evaluates a candidate's ability to serialize and format in-memory data structures for deterministic textual output, focusing on represen...
Validate Adding an Edge to a Directed Acyclic Graph
Determine whether a proposed directed edge is new and can be added to an existing DAG without creating a cycle. Reject self-loops and duplicates, then...