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.
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Solve capital selection and grid escape
Implement two functions for algorithmic practice: 1) MaximizeCapitalAfterProjects(k, initialCapital, requiredCapital, profit): You may pick at most k ...
Implement consistent hashing ring
Implement consistent hashing for routing keys to servers. Provide APIs addNode(nodeId, weight), removeNode(nodeId), and getNode(key). Use virtual node...
Implement core graph algorithms for graphics
Given a scene or dependency graph, implement topological sort, BFS/DFS, and shortest path (Dijkstra). Discuss time/space complexity, memory layouts (C...
Find minimum processing rate
You are given an array piles where piles[i] is the number of items in the i-th pile and an integer H (total hours). Find the minimum integer rate R su...
Implement a recent-use eviction cache
Design a fixed-capacity key-value cache that removes the least recently accessed item when it becomes full. Implement a class with the following opera...
Solve word path in grid and trapped water
You are given two independent programming tasks. --- Problem 1: Check if a word exists in a 2D character grid You are given a 2D grid board of charact...
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 an IPv4 Range Iterator
Implement a class that iterates through IPv4 addresses across multiple inclusive ranges. Each range is given as a pair of IPv4 addresses in dotted-dec...
Implement Fibonacci with efficiency constraints
Write a function fib(n) that returns the nth Fibonacci number (0-indexed: fib(0)=0, fib(1)=1). Requirements: - Handle n up to at least 10^6. - Discuss...
How do you expand nested placeholders in strings?
You are given a dictionary of string templates. Keys are identifiers like X, Y, Z. A template may contain placeholders of the form %KEY%, which should...
Maintain median of a data stream
Design a data structure that supports: - addNum(int x): Add an integer from a stream. - findMedian(): Return the median of all inserted numbers so far...
Find Shortest Paths in Road Network
You are reviewing code for a road-network graph. The domain objects are: `java class Location { String name; Location(String name) { this.name...
Find cheapest flight with at most K stops
Problem You are given a directed weighted graph representing flights between cities. Inputs - An integer n: number of cities, labeled 0..n-1. - A list...
Solve tree, graph, sliding-window problems
Question LeetCode 103. Binary Tree Zigzag Level Order Traversal – given a binary tree root, return its zigzag level-order traversal. LeetCode 207. Cou...
Solve grid shortest path and robot cleaning
Question LeetCode 1091. Shortest Path in Binary Matrix; LeetCode 489. Robot Room Cleaner https://leetcode.com/problems/shortest-path-in-binary-matrix/...
Manage GPU Credits with Expiration
Question Implement a GPU credit manager supporting out-of-order operations: API add_credit(id, amount, timestamp, expiration) // adds ‘amount’ credit...
Solve string match and DashMart BFS
Question Implement a string-matching function that returns the first index of a pattern in a text (akin to LeetCode 28 Implement strStr()). 2) “Dash M...
Validate Unit-Test Coverage and Identify Missing Scenarios
Scenario Tech round: reviewing an existing unit-test that exercises the class from Part 2 Question i) What does the current unit-test validate? ii) Li...
Solve Data-Structure Problems in Python Interview Round
Scenario Interview coding round focusing on simple data-structure problems in Python. Question Given an integer, rearrange its digits (considering onl...
Find shortest subarray with range ≥ k
Problem You are given an integer array nums of length n and an integer k. Define the range of a subarray as: \[ \max(\text{subarray}) - \min(\text{sub...