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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"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
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Design a no-repeat top-frequency music player
Design and implement a music player that receives song lists from new users and returns songs to play in frequency order without repeating a song in t...
Implement matrix multiplication and fast exponentiation
1) - A n × m - B m × p C = A × Bn × p - - - MOD MOD 2) Exponentiation by Squaring x k MOD - x^k - x^k mod MOD - O(log k) - k = 0x = 0 3) ...
Maximize total bandwidth of data channel pairs
You are optimizing how information flows through a network of processing nodes. There are n processing nodes. The bandwidth capability of the i-th nod...
Field Layout: getOffset and insert
An object's binary layout is defined by an ordered list of fields. Each field has a unique name and a size in bytes. Fields are packed contiguously st...
Check if a numeric string is divisible by 8
Question You are given a very large non-negative integer represented as a decimal string s (it may be too large to fit in standard 64-bit integer type...
Implement dynamic batching for token decoding
You are given a black-box “simulated language model” interface that can advance many sequences in a batch. Model interface - Tokens are integers. - mo...
Compute square root to 1 decimal
Problem Given a non-negative real number x, implement a function sqrt1dp(x) that returns \(\sqrt{x}\) rounded (or truncated—clarify with interviewer) ...
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...
Compute optimal matrix multiplication order
Given an array dims[0..n] where matrix i has dimensions dims[i-1] × dims[i] (for i = 1..n), compute the minimum number of scalar multiplications neede...
Design menu DP and optimize for three items
You are given a restaurant menu with n single items and m combo offers. Each single item i has a price p[i] (in cents). Each combo j specifies nonnega...
Compute minimum resources for overlapping intervals
You are given n tasks as half-open time intervals [start, end) on a single day. Determine the minimum number of identical servers needed so that no tw...
Find first error and propagate failures
You are given a chronological log history where each entry is a string prefixed with one of [Info], [Warn], or [Error]. Two invariants hold: ( 1) once...
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 ...
Find substring where all chars appear at least k
You are given a string s and an integer k (1 ≤ k ≤ |s|). Return the length of the longest substring in which every distinct character occurs at least ...
Solve build ordering and expression evaluation
Part A — Dependency ordering: You are given an integer n (0 ≤ n ≤ 200000) representing tasks labeled 0..n-1 and a list of prerequisite pairs [a, b] me...
Design file deduplication algorithm
Design an algorithm to deduplicate files in a storage system. Compare fixed-size versus content-defined chunking and explain how you would choose hash...
Implement a sliding-window hit counter
Implement a hit counter that supports recordHit(timestamp) and getHits(pastSeconds). Use a fixed-size array to maintain a sliding time window (e.g., l...
Implement bounds, minimum, pathfinding, and moving average
Solve the following data-structures problems: ( 1) Given two sorted integer lists A and B, merge them into a single non-decreasing array. Then, for a ...
Implement DFS for connected components
Given an undirected graph with n nodes (1 ≤ n ≤ 200, 000) and an edge list, implement depth-first search to compute (a) the number of connected compon...
Implement precise string-based decimal addition
Given two non-empty strings representing decimal numbers (e.g., "123.456" and "6234.42432"), implement a function that returns their exact sum as a st...