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."
"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 a Radix Cache for Integer Sequences
Implement a RadixCache — a radix tree (prefix-compressed trie) that stores sequences of integers. In a plain trie, every node holds exactly one elemen...
All Subsequences After Deleting One Character
You are given a string s of length n consisting of lowercase English letters. Consider every string that can be obtained by deleting exactly one chara...
Autoscale a Server Fleet from Throughput Readings
You run a service on a fleet of identical servers behind a load balancer. Each server can handle at most limit units of throughput. A monitoring syste...
Count ordered pairs that concatenate to target
Given a list of integers numbers and an integer target, count the number of ordered pairs (i, j) with i != j such that concatenating numbers[i] follow...
Solve matrix add, frequency count, longest consecutive
You are asked to solve the following 3 coding tasks (in any language). Implement each as a function. 1) Add two matrices Input: Two 2D integer arrays ...
Implement stream line reader and settle balances
Part 1: Streaming line reader from chunked source You are given an existing class ChunkSource with a method nextChunk() that returns the next piece of...
Find two numbers summing to target
Given an unsorted integer array and a target value, return the indices of two distinct elements whose sum equals the target. Aim for an O(n) time solu...
Implement a tennis score tracker
Design and implement a tennis game scoring function. Input: a stream of points won by players 'A' or 'B' (e.g., A, B, B, B, B). After each point, outp...
Solve max-subarray, min-unique, and grid-jump
1) Given an integer array nums, find a contiguous subarray with the maximum possible sum. Return (maxSum, startIndex, endIndex). If multiple subarrays...
Design an O(1) eviction cache
Implement an in-memory key–value cache with fixed capacity that evicts the least recently used entry when full. Support get(key) -> value or -1 if mis...
Find earliest time password becomes irrecoverable
You are given a password string of length n and an attack order array attackOrder[1..n], a permutation of 1..n. At second i (1-indexed), the virus rep...
Implement write with internal buffer
Implement a buffered writer over an expensive sink API. You are given a function writeToDevice(byte[] chunk) that may accept at most M bytes per call ...
Pass functions and analyze basic data structures
Implement a function applyTwice(f, x) that accepts a function f and a value x and returns f(f(x)) in your preferred language. Demonstrate how to pass ...
Design dasher-to-order assignment algorithm
You are building a real-time 'dasher picker' that assigns delivery drivers (Dashers) to incoming orders. Define objective(s) (e.g., minimize ETA and c...
Find returning users from access logs
Given an unordered log of web access events, identify which users are returning (i.e., they have visited on at least two different calendar days). Eac...
Design an in-memory database with TTL and history
Design and implement an in-memory key–field–value store with monotonic timestamps. Keys and fields are strings; values are integers. Provide these API...
Implement power and balance-parentheses algorithms
Design and implement two algorithms: 1) Fast exponentiation: Implement a function pow(x, n) that returns a real number x raised to an integer exponent...
Implement BST vertical traversal and list conversion
Given the root of a binary search tree (BST): 1) Implement vertical order traversal: assign the root column 0, left child column −1, right child colum...
Implement banking ops: transfer, top-k, cashback, merge
Design and implement an in-memory banking system that supports: ( 1) CreateAccount(id, initialBalance) and Transfer(fromId, toId, amount) with validat...
Implement exponentiation and link tree neighbors
Solve two independent tasks. Task A — Fast exponentiation: Implement fastExponent(x, n) that returns x raised to the integer power n, where x is a dou...