Coding & Algorithms Interview Questions
Practice 3,013 real Coding & Algorithms interview questions for 2026. Coding & Algorithms interview questions for top tech firms like Meta, Amazon, Google, Uber, and TikTok — real questions from actual interviews with detailed solutions — to power your interview preparation. This collection is sharply focused on algorithmic patterns (arrays, strings, sliding windows, trees/graphs, dynamic programming, greedy, two-pointers, and hashing), clean, review-ready code, and the explanation skills that distinguish hires. In 2026 expect familiar medium-to-hard problems plus newer twists: AI-enabled or multi-file coding rounds at some companies, more emphasis on explainability and edge-case reasoning, and occasional real-world performance constraints (streaming, concurrency, memory limits). Interviewers evaluate problem framing, algorithm choice, complexity trade-offs, test-case thinking, and communication under time pressure. Best prep mixes pattern-based practice, timed mock interviews, code-review style polishing, and rehearsed explanations of complexity and tradeoffs. Focus your last-mile prep on writing correct, readable code quickly and on explaining why your solution is robust and efficient for production scenarios.
"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."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"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."
Generate All Valid Combinations of Balanced Parentheses
Generate All Valid Combinations of Balanced Parentheses Given an integer n representing the number of pairs of parentheses, generate all distinct stri...
Build a Quadtree and Analyze a Graph
Solve the following two coding problems. 1. Build a quadtree from an image You are given an N x N matrix of integers representing an image, where N is...
Solve Signature, File, and Queue Problems
Solve the following interview-style problems: 1. Function signature matching You are given a registry of function definitions. Each function has an...
Find k most frequent elements, discuss O(n)
Question Given an integer array nums of length n and an integer k (where 1 ≤ k ≤ the number of distinct values in nums), return any ordering of the k ...
Compute subarray span for each element
You are given an integer array nums of length n. For each index i (0 <= i < n), define ans[i] as the maximum possible length of a contiguous subarray ...
Find minimum shuttle transfers
You are given a collection of shuttle loops, each represented by a list of stop IDs that the loop visits in perpetuity. You may board a shuttle at any...
Transform tree with subtree sum mapping
You are given the roots of two complete binary trees T1 and T2 that have identical structure (same shape and number of nodes). Modify T2 so that, for ...
Simulate bubble elimination and maximize common prefix
You are given two independent coding tasks (as in a multi-question OA). Solve each. Task A — Grid “bubble/candy” elimination simulation You are given ...
Implement bag-of-words similarity search from scratch
Implement a bag-of-words–based text similarity search engine from scratch. Write code that: ( 1) tokenizes text (lowercasing, punctuation handling, Un...
Simulate In-Place Cellular State Updates
You are given an m x n grid of cells, where each cell is either 0 for inactive or 1 for active. All cells update simultaneously according to these rul...
Implement a thread-safe high-concurrency LRU cache
Problem Design and implement an in-memory LRU (Least Recently Used) cache that supports concurrent access. Basic requirements Implement a cache with f...
Design playlist with add/remove/shuffle
Music Playlist Data Structure Design an in-memory Playlist data structure that supports the following operations on a set of songs: - add(songId): Add...
Deep copy a linked list with random pointers
Problem You are given the head of a linked list where each node has: - val: integer value - next: pointer to the next node (or null) - random: pointer...
Find two numbers summing to target without hashmap
Problem Given an integer array nums (length n) and an integer target, return the indices (i, j) such that: - i != j - nums[i] + nums[j] == target You ...
Validate hiring request under role constraints
Problem You are building a simple HR assignment validator for a platform with companies, employees, and job roles. When the system receives a request ...
Merge collinear overlapping 2D segments
You are given a collection of 2D line segments. Each segment may be represented either as: - two endpoints (x1, y1) and (x2, y2), or - a polyline with...
Check if one string is a subsequence of another
Given two strings s and t, determine whether s is a subsequence of t. A subsequence keeps relative order but does not require contiguous characters. I...
Find kth smallest and count stair-climbing ways
You are given two separate algorithm questions. A) Find the k-th smallest element in an array (no sorting) Given an integer array nums of length n and...
Serialize and deserialize a binary tree
Problem Design two functions to serialize and deserialize a binary tree. - Serialize: convert a binary tree into a single string. - Deserialize: recon...
Compute minimax grid path and network delay
Problem (two related shortest-path tasks) Part 1 — Minimize the maximum value along a grid path ("minimax" path) You are given an m x n integer grid H...