Sr. Software Engineer, Web Platform

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You are given the head of a singly linked list. Implement a function to determine if the linked list is a palindrome. A palindrome is a sequence that reads the same backward as forward. Example 1: Input:** head = [1, 2, 2, 1] Output:** true Example 2: Input:** head = [1, 2, 3, 2, 1] Output:** true Example 3: Input:** head = [1, 2] Output:** false Constraints: The number of nodes in the list is in the range [1, 10^5]. 0 <= Node.val <= 9 Your function should efficiently determine if the linked list forms a palindrome. Consider space and time complexity optimizations. For instance, think about how you can achieve this without using extra space (O(1) space complexity) or minimizing the time complexity to O(n). Can you solve this by reversing the second half of the list and comparing it with the first half?

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System Design: Google Calendar Let's design a system similar to Google Calendar. Consider the following requirements: Functionality: Users should be able to create, read, update, and delete (CRUD) events. Events should have a title, description, start time, end time, location, and attendees. Recurring Events: Support recurring events (e.g., daily, weekly, monthly) with options for specifying exceptions (e.g., skip a specific instance). Invitations and Notifications: Users should be able to invite other users to events. Invited users should receive notifications about new events, updates, and cancellations. Implement a notification system, detailing frequency and method (e.g., email, push notification). Reminders: Users should be able to set reminders for events (e.g., 10 minutes before, 1 hour before). Time Zones: The system must correctly handle events across different time zones. Availability: Users should be able to view the availability of other users when scheduling events (free/busy). Scalability: The system should be able to handle a large number of users and events, ensuring responsiveness and reliability. How would you scale the system to accommodate millions of users and concurrent events? Consistency: Ensure data consistency across different users' views of the same event. Conflict Resolution: Address how to handle conflicting events and notify users accordingly. Specifically address these points in your design: Data model: How would you represent events, users, and their relationships in a database? API design: What API endpoints would you provide for creating, reading, updating, and deleting events? Concurrency and locking: How would you handle concurrent access to events to prevent data corruption? Notification system: How would you implement the notification system for event invitations, updates, and reminders? Scalability strategies: What strategies would you use to scale the system to handle a large number of users and events? Conflict Detection: How will the system determine event conflicts, and what notification mechanisms will be in place?

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