Coding & Algorithms Interview Questions
Practice 2,960 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.
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Implement a Leaky Bucket Limiter
Design and implement an in-memory leaky-bucket rate limiter. A limiter is configured with: - capacity: the maximum amount of queued load the bucket ca...
Validate Nested Configuration Objects
You are given a set of custom descriptor objects that define the expected schema of a configuration object. Implement a validator that checks whether ...
Implement trie-based autocomplete
Problem Design an autocomplete data structure using a trie. You must support: 1. insert(word: string) -> void 2. search(word: string) -> bool (exact m...
Find Words in a Character Grid
Implement findWords(board, words) for a word-search game. You are given an m x n grid of lowercase English letters and a list of lowercase dictionary ...
Flip a specific bit in an integer
Given a non-negative integer num and a zero-based bit position p, return the integer resulting from flipping only the bit at position p (i.e., 0 becom...
Solve tree view and parentheses cleanup
Solve the following two algorithm problems. 1. Right-side view of a binary tree Given the root of a binary tree, return the values of the nodes that w...
Solve transaction aggregation and search tasks
Complete the following coding tasks: (a) Given a list of transactions, each with userId and amount (credits positive, debits negative), compute the fi...
Compute ring window max and deletion indices
Part A — Ring window maximum: You are given n computers arranged in a circle, represented by an array of bits (1 = on, 0 = off), and an integer k (1 <...
Find Minimum Time Across a Grid
You are given an n x n grid of non-negative integers. Each value represents the earliest time at which that cell becomes traversable. You start at the...
Find spammer with minimal hasMessaged calls
Question You have n accounts labeled 0..n-1 and an oracle API: ` boolean hasMessaged(a, b) // true iff account a has sent at least one message to ac...
Maximize profit with bounded sell window
Given an array prices[0..n-1] of daily stock prices and an integer D ≥ 1, you may perform at most one transaction (buy then sell). The sell day j must...
Explain C++ vector, unordered_map, and virtual functions
In C++, explain: - The amortized and worst-case time complexity of vector::push_back, and how capacity growth/expansion is implemented (growth factor,...
Implement scalable prime generator
Write a function first_n_primes(n) that returns the first n prime numbers in ascending order. Constraints: - 1 ≤ n ≤ 100,000. - Aim for O(n log log n)...
Solve two interview coding problems
This interview included two coding tasks: 1. Currency conversion graph You are given a set of directed currency exchange rates, for example: - C...
Solve BFS and grid tasks
The coding rounds included several algorithmic problems: 1. Threshold search with binary search: You are given floors 1..n and an API canOperate(floor...
Determine Reporting Relationships
Build an in-memory organization model that supports three operations on employee IDs: 1. add_manager(a, b): employee a is the direct manager of employ...
Can you reach target with distance-threshold edges?
You are given a set of unordered 2D points points[], a start point and an end point (both are included in points), and a function: `text getDistance(p...
Implement price-based order matcher
Design and implement a price-based order matcher for unit-sized orders. You are given an array orders where each element is [type, price]: type = 1 de...
Implement stack variants and upward path sum
Question Answer the following coding questions. They progress from augmented stacks to streaming statistics to tree path reasoning. 1. MinStack — Desi...
Return sorted squares of a sorted array
Problem You are given an integer array nums sorted in non-decreasing order. The array may contain negative numbers. Return a new array containing the ...