Uber

A centralized coordination service for distributed systems providing configuration management, leader election, distributed locking, and service discovery

A document-oriented NoSQL database designed for flexible schemas, horizontal scaling, and developer productivity

Distributed NoSQL database designed for high availability, linear scalability, and handling massive amounts of data across multiple data centers

Distributed stream processing framework for real-time analytics, event-driven applications, and complex event processing

Distributed streaming platform designed for high-throughput, real-time data pipelines and event-driven architectures

Unified analytics engine for large-scale data processing with built-in modules for streaming, SQL, machine learning and graph processing

Learn BFS shortest path in an unweighted graph: O(V+E) time, queue + parent[] for path reconstruction. Step-by-step for interviews—start now.

Create a deep copy of an undirected graph represented with adjacency lists

Determine if you can finish all courses given prerequisite relationships using topological sorting

Techniques for migrating data between different schemas and systems

Determine if a directed graph contains a cycle

Find the minimum number of operations (insert, delete, replace) required to transform one string into another.

Distributed search and analytics engine built on Apache Lucene for real-time search, logging, and data analytics

Retry strategy that progressively increases delay between retry attempts to handle transient failures and prevent system overload

Find all bridges (critical edges) in an undirected graph using Tarjan's algorithm

Find the duplicate number in an array containing n+1 integers where each integer is between 1 and n (inclusive)

Find the majority element that appears more than n/2 times using Boyer-Moore majority vote algorithm

Design data structure to find median from continuous stream of integers

Find and return the second largest element in an array of integers

Find shortest paths between all pairs of vertices in a weighted graph using dynamic programming

Given an array of strings, group the anagrams together.

Scaling strategy that increases system capacity by adding more machines or instances rather than upgrading existing hardware

Design and implement a stack data structure with push, pop, top, and empty operations

Check if a graph can be colored with exactly two colors such that no two adjacent nodes have the same color

Find the kth largest element in an unsorted array

Find kth smallest element in row and column sorted matrix using heap

Find the length of the longest substring without repeating characters

Design a data structure that follows Least Recently Used (LRU) eviction with O(1) get and put operations.

Find minimum number of meeting rooms required using heap

Given an array of intervals where intervals[i] = [start_i, end_i], merge all overlapping intervals and return an array of the non-overlapping intervals that cover all the intervals in the input.

Merge k sorted arrays into one sorted array using heap

LeetCode 88 merge sorted array in-place: reverse two pointers (merge from end) in O(m+n) time, O(1) space. Step-by-step + examples.

Given arrival and departure times of trains at a station, find the minimum number of platforms required so that no train is kept waiting

Move all zeros in an array to the end while maintaining the relative order of non-zero elements

Find the time it takes for a signal to reach all nodes in a network using shortest path algorithms

Concurrency control mechanism that assumes conflicts are rare and handles them when they occur, using version numbers or timestamps to detect concurrent modifications

Rotate an array to the right by k steps where k is non-negative

Given a rotated sorted array and a target value, return the index of the target if found in O(log n) time, or -1 if not present.

Hard LC 480: rolling median via sliding window + two heaps w/ lazy deletion. O(n log k) time, O(k) space. Step-by-step solution—prep now.

Find all unique triplets in the array which gives the sum of zero

Solve LeetCode 347 Top K Frequent Elements (Medium) with frequency map + bucket sort O(n) or min-heap O(n log k). Step-by-step for interviews.

Find a linear ordering of vertices in a directed acyclic graph

Calculate how much rainwater can be trapped between bars of different heights

Determine if two strings are anagrams of each other

Find the shortest transformation sequence from beginWord to endWord using single character changes