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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"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."
Simulate toppling board game outcome
Implement a function that, given the board size N (3–9 inclusive) and a list of move strings, returns one of: "in progress", "player 1 is the winner",...
Evaluate expression without stack, constant space
Evaluate expression without stack, constant space Given a string s representing a valid arithmetic expression of non-negative integers, the operators ...
Design a temporal key-value store with historical reads
Implement a key–value store supporting set(key, value, timestamp) and get(key, timestamp) -> the value at the greatest timestamp ≤ the given timestamp...
Stone Pile Doubling Game: Can One Pile Be Emptied?
You are given two piles of stones containing a and b stones respectively (both piles start non-empty). You repeatedly apply the following move: - Let ...
Count clusters covered by dashers
Count clusters covered by dashers You are given two m×n binary matrices of equal size: D for dasher availability and U for user presence. A cell value...
Find latency pairs with minimal difference
Given an array of integers representing network latencies, return all increasing pairs [a, b] such that b − a equals the minimal absolute difference b...
Solve increasing sequence and path problems
Solve increasing sequence and path problems Answer the following related tasks about increasing sequences and paths: a) Contiguous subarray: Given an ...
Implement Minesweeper click and print
Implement Minesweeper click and print Implement the Minesweeper click(row, col) operation and a function to print the board. Rules: ( 1) If the clicke...
Determine if robot path is bounded
Determine if robot path is bounded A robot starts at (0, 0) facing North on an infinite grid. It executes a string s consisting of 'G' (move forward 1...
Implement classes in existing abstract hierarchy
You are given an existing Python codebase that defines multiple classes, including abstract base classes using abc.ABC and @abstractmethod decorators....
Decompress an encoded string
Decompress an encoded string Given an encoded string, return its decoded (decompressed) form. Use the following encoding rule: - A positive integer \(...
Validate a Binary Tree Built from Directed Edges
Validate a Binary Tree Built from Directed Edges You are given a list of directed edges. Each edge is a pair (parent, child) of positive-integer node ...
Implement a hierarchical key-value store
Implement a hierarchical key-value store Implement an in-memory hierarchical key-value store where keys are UNIX-like paths joined by '/'. The root no...
Solve binary tree, grid, and heap tasks
Solve binary tree, grid, and heap tasks Answer the following independent coding tasks: 1) Range sum in a BST: Given the root of a binary search tree a...
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 ...
Implement inventory allocation with backorders
Implement inventory allocation with backorders Design and implement a function to process an event stream for an e-commerce marketplace. Input: ( 1) i...
Identify and prevent code-breaking inputs
Identify and prevent code-breaking inputs Identify inputs and scenarios that could break your implementation and explain how you would prevent them. C...
Identify OS component causing process starvation
A system with 2 CPU cores runs 5 identical processes continuously. Four processes get equal CPU time, but the fifth appears to get none. Which part of...
Solve two DS&A optimization problems
Problem 1 — Maximize alternating-sum over four array partitions: Given an integer array arr[1..n] (1-based). Choose indices a, b, c with 1 ≤ a ≤ b ≤ c...
Find shortest word transformation with caching
Find shortest word transformation with caching You are given a start word and an end word of equal length, and a dictionary of valid words. In one mov...