An arithmetic sequence is a list of numbers with a definite pattern. If you take any number in the sequence then subtract it from the previous one, the difference is always a constant. A good arithmetic sequence is an arithmetic sequence with a common difference of either 1 or -1. For example, [4, 5, 6]…

This problem is a standard weighted random selection. Build a prefix-sum array based on city populations and map a random value into one of the prefix intervals. This guarantees output probabilities match the weight distribution, and repeated queries remain efficient. The key is prefix sums plus binary search for fast selection. The BST property allows…

The solution uses a stack to simulate function calls. A“begin”event pushes a new frame and pauses the previous function, while an“end”event pops the function and accumulates its exclusive time based on timestamp differences. Properly tracking the previous timestamp is essential to handle nesting correctly. The VOprep team has long accompanied candidates through various major company OAs and…

Standing on the left side gives the leftmost node of each level, but the ordering must be reversed from bottom to top. Standing on the right side gives the rightmost node level by level from top to bottom. The problem is solved with BFS level traversal and extracting the appropriate visible node at each level….

This is the 2D extension of the range counting problem. Build a 2D prefix-sum matrix pre[i][j] for ones in the rectangle from (0,0) to (i,j), then answer any subgrid query in O(1) time using the inclusion–exclusion formula. It tests understanding of 2D prefix sums and careful boundary handling The VOprep team has long accompanied candidates through various…

This problem is a classic range query task. The optimal solution precomputes a 1D prefix-sum array where prefix[i] stores the number of ones up to index , then each query runs in O(1) time using prefix[end] – prefix[start-1]. It tests preprocessing, time–space trade-offs, and clean API design. The VOprep team has long accompanied candidates through various major…

The task is to evaluate an expression with only + and *, respecting operator precedence. Typical solutions use a stack to accumulate intermediate products, or track the current multiplication block during a single pass. The VOprep team has long accompanied candidates through various major company OAs and VOs, including Meta, Amazon, Citadel, SIG, providing real-time voice assistance,…

A classic weighted random selection question: build a prefix-sum array, generate a random number within the weighted range, and use binary search to find the correct index. Commonly tested in Meta interviews for probability distribution and prefix-sum logic The VOprep team has long accompanied candidates through various major company OAs and VOs, including Meta, Amazon, Citadel, SIG,…

This Meta interview question asks for all root-to-leaf path sums in a binary tree. A depth-first search is used to propagate the running sum, recording values when a leaf is reached. It tests recursion, tree traversal, and handling of leaf conditions. The VOprep team has long accompanied candidates through various major company OAs and VOs, including Meta,…

This problem tests arbitrary-base conversion where the number is stored as a linked list. The core idea is to extract the base-10 value, then repeatedly apply modulo and division to build the new-base list. It evaluates understanding of linked-list big-integer representation and digit extraction logic. The VOprep team has long accompanied candidates through various major company OAs…

Problem 1 — CICD Pipeline Dependency Ordering CICD Pipeline:- Different environments.- If nothing is in prod theDatamine the order in which we should deploy our resources. Questions:1. What are the inputs? [A,B] where A and B are resources. A depends on B – list of lists where each inner list is a dependency pair and…

This Microsoft interview problem focuses on weighted random selection. Given cities and their populations, the function should return a city name with probability proportional to its population. A common solution uses a prefix-sum array and binary search to map a random number to the correct weighted interval. The VOprep team has long accompanied candidates through various major…

There are 2 single linked list, one is ascending sorted, the other is descending sorted, write code to merge them together, result in ascending sorted. For example:L1: 1->2->3L2: 6->5->4 Result:1->2->3->4->5->6 Requirements:Time complexity: O(M + N), M is the length of L1, and N is the length of L2Space complexity: O(1) Please write code to solve…

Problem 1 Imagine you’re working on a language which only support Stack, but you need a Queue functionality to fulfill the requirement. Problem 2 Given:const a = 1;const b = ‘1’;What is the result of each of the following statements: a == ba === b!a === !ba + ba + +b These are typical Microsoft…

Recently, Microsoft interview activity has noticeably increased again. One thing that has always been true about Microsoft is that interview content heavily depends on the team — different teams test very different skills. This time, all three of my rounds followed the pattern of resume deep-dive + coding questions, with no system design and no…

Amazon SDE Intern Interview Experience — One Round to Decide Everything Amazon has started sending out OA invitations again recently. Over the past few weeks I helped several friends go through the process — and everything remains much the same as last year: OA format unchanged, interview setup consistent, and question types stable. Although the…

I recently had my on-site with Google and wanted to put together a clean, realistic walkthrough for anyone preparing. On-site write-ups are surprisingly rare, so hopefully this fills the gap. 🛫 Arriving at Google Google arranged the travel and hotel, so I flew in the day before. On interview day I showed up a bit…

Flight Booking (Python) This exercise provides a basic Python HTTP server used to track flight tickets and their prices.Your interviewer will explain the question; the README only contains usage hints.The main libraries include Flask (HTTP server) and psycopg2 (PostgreSQL client). Getting Started To start the database: Then, in another terminal: If psycopg2-binary fails to install,…

Problem 1 — Ticket Reservation API Design Codewriting How do you design the API/backend for a ticket reservation app?Examples include movie tickets or concert tickets.The app should allow users to hold their ticket(s) for 10 minutes before booking. Problem 2 — Third-Party Airline Booking APIs 3-party APIs Suppose we want to design an automated flight-booking…

📌 Problem Statement Imagine you have an RPC server that produces log entries and we’re analyzing it offline.There are two entries for each call: Your task is to efficiently determine if any RPC in the log timed out. You can assume your function receives two arguments: Example Input timeout: Input log: ID Timestamp Event Type…