Amazon | SDE-2 | Offer accepted 2022

Given a grid representing a field of oranges, where 0 represents an empty cell, 1 represents a fresh orange, and 2 represents a rotten orange. Every minute, any fresh orange that is 4-directionally adjacent to a rotten orange becomes rotten. Determine the minimum number of minutes that must elapse until no fresh oranges remain. If it's impossible for all fresh oranges to rot, return -1.

Given an m x n 2D binary grid which represents a map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.

Given the availability time slots for two people (slots1 and slots2) and a meeting duration, find the earliest time slot that works for both people and is at least of the given duration. Each slot is represented as [start, end]. Assume start < end and all times are non-negative integers.

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0. Notice that the solution set must not contain duplicate triplets.

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security systems connected and it will automatically contact the police if two adjacent houses were broken into on the same night. Given an integer array nums representing the amount of money in each house, return the maximum amount of money you can rob tonight without alerting the police.

Given a string s, find the length of the longest substring without repeating characters.

You are given an integer array prices where prices[i] is the price of a given stock on the ith day. On each day, you may decide to buy and/or sell the stock. You can only hold at most one share of the stock at any time. However, you can buy it then immediately sell it on the same day. Find the maximum profit you can achieve.

In the "Can I Win" game, two players take turns picking numbers from a common pool of integers ranging from 1 to maxChoosableInteger. The first player to accumulate a total sum of numbers that is equal to or greater than desiredTotal wins. Once a number is picked, it cannot be used again. Determine if the first player can win, assuming both players play optimally.

Design a parking lot system that supports multiple types of vehicles (e.g., motorcycles, cars, buses) and efficiently allocates the nearest empty parking slot. Consider using a data structure like a min-heap to optimize the slot allocation process.

Design the low-level architecture for a platform similar to StackOverflow. Your design should cover core entities such as users, questions (posts), answers, comments, tags, and votes. Detail the database schema (tables, relationships) and define the necessary APIs for key functionalities like posting a question, answering, commenting, and voting.

Design a high-level system for a locker delivery service, similar to Amazon Lockers. The design should focus on key aspects such as managing the availability of individual locker units, ensuring data consistency during the booking and reservation process, and generating secure, unique one-time passwords (OTPs) for customers to access their assigned lockers.

Design a scalable URL shortener service. This system should take a long URL as input and return a short, unique URL. Consider how to generate short codes, handle redirects, ensure high availability, and manage potential collisions or expired URLs. Discuss database choices, distributed systems considerations, and API design.