You are given an integer array coins representing coin denominations, and an integer amount representing a total amount of money. Return the fewest number of coins needed to make up the given amount.If it is not possible, return -1. You may use unlimited coins of each denomination. Example 1 Example 2 Use DP:dp[x] = min(dp[x],…

You are given an array of integers representing the amount of money stored in each house.The houses are arranged in a line, and you cannot rob two adjacent houses. Return the maximum amount of money you can rob without ever robbing two adjacent houses. Example (Explanation: choose non-adjacent houses so the sum is maximized.) Use…

Amazon has web server logs from multiple hosts.Each log entry consists of: Example (conceptual): We want to find the 3-page pattern that is visited most frequently across all sessions. In the example, the sequence <cart, checkout, help> appears twice, so it is the most frequent 3-page pattern. Given logs in the form: Return the 3-page…

Convert a number to an Excel column, and convert an Excel column back to a number. In Excel, columns are labeled as: You are asked to implement two functions: You may assume: The VOprep team has long accompanied candidates through various major company OAs and VOs, including Google, Amazon, Citadel, SIG, providing real-time voice assistance, remote practice,…

Implement the Linux find command as an API. Your API should support searching for files that match: Assume the filesystem is represented as a tree-like structure of directories and files. Your job:Design and implement a find-like API that searches the file system and returns all files that satisfy the given filters. Do a DFS traversal…

You are given a (potentially large) list of words.Some words are compound words, meaning they are composed of two or more words that also exist in the same list. Example word list:[rockstar, rock, star, rocks, tar, stars, rockstars, super, highway, high, way, superhighway] Goal:Identify all combinations where a word can be decomposed into two or…

Given an array of integers, find the index of a local minimum. A local minimum is defined as an element that is strictly smaller than its neighbors.Formally: You may assume: Goal:Return the index of one such local minimum. Example: You must return the index of any element that is strictly smaller than both neighbors.Since adjacent…

Implement the function pow(x, n), which calculates x^n.Note that you cannot use any built-in functions that directly implement pow. Examples: Key Ideas: This approach tests understanding of recursion, divide and conquer, and edge case handling (e.g. negative powers, floating-point base). The VOprep team has long accompanied candidates through various major company OAs and VOs, including SnowFlake, Google,…

Level 1 The basic level of the in-memory database contains records. Each record can be accessed with a unique identifier key of string type. A record may contain several field – value pairs, both of which are of string type. Function Definitions Examples Queries Explanations set(“A”, “B”, “E”) database state: {“A”: {“B”:“E”}} set(“A”, “C”, “F”) database state: {“A”: {“C”:“F”,“B”:“E”}}…

Your team is debugging a program’s performance. A tracing tool records all function calls and returns, producing a sequence of events.Your task is to analyze these raw traces and determine which call stack occurs most frequently.Finding the most frequent call stack will help identify where the main slowdown may be occurring. Input Output Call Stack…

Roblox has a marketplace with millions of items. A user can flag/unflag any item as a favorite (similar to Like/Bookmark).Goal: Design a system that can show the number of favorites each item has. User Stories / QPS targets Extra:– As a user, I want to list all items I have favorited — 50K QPS (Insert…

This question focuses on system design and scalability within the context of Roblox’s Game Detail Page.You’re asked to design how to efficiently display: while considering massive user scale (100M total, 10M concurrent). Key challenges include: Typical design solutions might involve: The VOprep team has long accompanied candidates through various major company OAs and VOs, including Roblox, Google,…

Companies like Google, Apple, Microsoft, etc. offer various services such as drive, photos, mail, and documents.Typically, they provide users with a single shared quota. For example, if you purchase a 100GB storage plan,all these services will consume capacity from the same quota bucket. Under the hood, such systems usually look like this: Applications and services…

Example: Matrix: Words: Output: [‘abe’] This problem asks you to check which of the given words can be found in a 2D character matrix. A valid word must be formed by adjacent characters in the matrix, typically in horizontal or vertical directions (depending on the interviewer’s clarification). The task is essentially a simplified version of…

SnowCal is a simple programming language used to perform calculations. A SnowCal program keeps a single integer X in memory, initially set to zero, and repeatedly performs addition and multiplication operations on it. Formally, the language has 5 operations: Write an interpreter that takes in the commands as an array of strings and returns the…

Each person wants to eat one cake. People tend to get the cake that is the closest to him/her.However, if he/she finds that this cake already belongs to someone else, the person will give up that cake and look for the next closest cake. The number of cakes is never smaller than the number of…

Given a 1-d space, represented as an int array.Each element in this array can have one of the three values {0, 1, 2} with meanings: The distance between a cake and a person is defined as the number of spaces between them. Please write a method to get the minimum distance between any person and…

Given an m × n array of characters, and a list of strings.Return the subset of the strings that are found in the array. You are given a character grid and a list of candidate words.Your task is to return all words that can be formed by tracing adjacent cells in the grid (typically up,…

Problem statement:Given an array of strings (terms) and a target string, find the number of occurrences of each term in the target. You only need to implement the Count method. Parameters / Requirements: Without regex, implement multi-pattern counting. Options: naive sliding checks with indexing by first letter/length, or Aho–Corasick for optimal performance. Count overlapping matches…

Given two integers, numerator and denominator, return the decimal representation of the fraction numerator/denominator as a string. Examples Simulate long division. Track each remainder’s first index in the fractional string via a hash map. When a remainder repeats, insert parentheses around the substring from its first occurrence to the end. Handle sign, zero integer part,…