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."
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"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."
Compress Consecutive Characters with Run Lengths
Compress Consecutive Characters with Run Lengths Implement compress_runs(s) and return the compressed string. The input contains ASCII letters only. S...
Maximize Profit with One Stock Transaction
Maximize Profit with One Stock Transaction Implement max_profit(prices) for daily integer prices. Choose at most one buy followed by one later sell an...
Implement local maxima, bagging, and k-means
This question evaluates skills in algorithm implementation and machine learning fundamentals—specifically streaming local maxima detection, bootstrap ...
Deep-Copy a Linked List with Random Pointers
Clone a linked list whose records use arbitrary IDs for next and random pointers. Translate every identity and pointer through supplied fresh IDs whil...
Deep-Copy a Linear Linked List
Deep-copy a finite singly linked list represented by nested Python lists. Preserve values and structure while allocating every returned node independe...
Implement stream queries and bounded-difference subarrays
This question evaluates proficiency in data structures and algorithmic problem-solving, covering streaming uniqueness tracking (first-non-repeated ele...
Build Event Notification Engine
You are implementing part of a marketing engine for an event marketplace. Assume the following data is available: - Customer: id, city, birth_month, b...
Implement a Time-Aware Task Manager
This question evaluates the ability to design and implement in-memory data structures and algorithms for time-aware state management, including per-us...
Solve three algorithmic OA problems
This is an online assessment (Codility-style, 150 minutes) consisting of three independent coding problems. Solve each one separately; they do not sha...
Find Optimal Property Combination
This question evaluates combinatorial optimization and algorithmic problem-solving skills, focusing on subset selection under capacity constraints and...
Solve common string and subarray problems
You are given three coding tasks: 1) Reverse a string - Input: a string s. - Output: the string with characters in reverse order. 2) Maximum sum of a ...
Solve Rooms and Top-K Streams
This question evaluates algorithmic problem-solving skills across interval scheduling/resource allocation and streaming top-k maintenance, testing com...
Shortest Bridge to Connect Two Islands
You are given an n x n grid where each cell is either water (0) or land (1). Land cells that are adjacent horizontally or vertically belong to the sam...
Compute the Product of an Array Except Self
The interview report preserved the input-output example but not every original restriction. The following is a self-contained version of the reported ...
Design an In-Memory Spreadsheet Engine
This question tests a candidate's ability to design a dependency-tracking data structure with efficient cache invalidation, drawing on graph traversal...
Solve Two OA Coding Problems
The online assessment included two coding problems: 1. In-place character run compression - You are given an array of characters. - Compress con...
Implement Autoregressive Decoding Strategies
This question evaluates proficiency with autoregressive sequence generation, probabilistic sampling methods (greedy, top-k, top-p), softmax-based prob...
Compute Theme Similarity
This question evaluates understanding of set-based similarity metrics (the Jaccard coefficient) and practical coding skills for transforming and compa...
Implement crawler, dedup, and persistent LRU
Implement crawler, dedup, and persistent LRU LeetCode 1236. Web Crawler: Crawl web pages starting from a given URL within the same hostname. LeetCode ...
Merge Message Context Windows
This question evaluates a candidate's skill in designing efficient algorithms and appropriate data-structure use for merging overlapping message conte...