Coding & Algorithms Interview Questions
Practice 2,950 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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Count Nodes Using Asynchronous Messages
You are given the identifier of a root node in a distributed network. Each node represents a separate machine. A node cannot directly inspect another ...
Find shortest subarray with at least k distinct
Problem Given an integer array nums and an integer k, find the length of the shortest contiguous subarray that contains at least k distinct integers. ...
Maximize sum without choosing adjacent elements
Problem You are given an integer array nums where nums[i] is the value in position i. Select a subset of indices such that no two selected indices are...
Validate whether brackets are properly nested
Problem: Validate a bracket sequence Given a string s consisting only of the characters '(', ')', '{', '}', '[', ']', determine whether the string is ...
Implement a Contiguous Memory Manager
You are asked to implement a contiguous memory manager for an array of n memory cells indexed from 0 to n - 1, where all cells are initially free. Sup...
Solve Five Coding Problems
The interview included several coding tasks. Solve each of the following and discuss time and space complexity: 1. Given a 2D grid where '1' represent...
Minimize time for two handlers
You are given a sequence of jobs that must be processed in the given order. There are exactly two handlers, and each job must be assigned to one of th...
Implement cluster status tracker
Implement a cluster status tracker. Design a class with methods: update(nodeId, status, timestamp) to record node status updates that may arrive out o...
Implement Optimal Bucket Batching
You are given an array lengths of K document lengths and an integer G representing the number of available GPUs. A batch is assigned to one GPU, and e...
Evaluate Piecewise Linear Function
Given a list of 2D points [(x1, y1), (x2, y2), ..., (xn, yn)], where the points are ordered by strictly increasing x, connect each consecutive pair of...
Decide and implement DP/heap and approximation
You have 90 minutes to complete three related coding tasks: a) Dynamic programming: Given an integer array nums (n ≤ 2e 5) and a threshold T, design a...
Generate all subsets (handle duplicates)
Problem Given an integer array nums, return all possible subsets (the power set). Part A (no duplicates) Assume all elements in nums are distinct. Ret...
Make a Parentheses String Valid
Given a string s containing lowercase English letters and the characters '(' and ')', remove the minimum number of parentheses so that the resulting s...
Implement nested template string substitution
You are given a dictionary (map) from keys to string templates. Templates may reference other keys using placeholders of the form %KEY%. Example dicti...
Implement a Streaming VMStat Alert
Write a command-line program that reads a continuous stream of vmstat-style output from standard input and raises an alert based on a sliding time win...
Can one car serve all riders?
Given a list of passenger waiting intervals, determine whether a single car can serve all passengers without any scheduling conflict. Each interval is...
Design O(1) Randomized Multiset
Implement a randomized multiset data structure that allows duplicate values and supports the following operations in average constant time: - insert(v...
Find Duplicate Files
Implement a file deduplication tool. You are given a root directory containing many files. Return groups of duplicate files. Two files are duplicates ...
Answer static and streaming Top-K queries
Top-K in static and streaming settings (3 variants) You are given integers and asked to answer Top-K queries under three different scenarios. Variant ...
Solve 15 common Apple coding questions
The post summarizes high-frequency coding problems reported for Apple Software Engineer interviews. Practice the following algorithm and data-structur...