1. Application and Screening

• Resume Submission: You apply through Microsoft's career portal, a recruiter, or via referral.
• Recruiter Screen: If your resume is selected, a recruiter will usually reach out to schedule a short phone call to discuss your experience, role expectations, and clarify any questions about the role. This call might also assess your cultural fit and career goals.

1. Online Assessment (for certain roles)

• Before proceeding to interviews, you may be asked to complete an online coding assessment, typically hosted on platforms like Codility or HackerRank.
• The assessment usually focuses on data structures, algorithms, and problem-solving.

1. Technical Phone/Virtual Interview

• The next step is often a virtual technical interview with a Microsoft engineer, lasting about 45-60 minutes.
• Expect coding challenges focused on data structures, algorithms, and sometimes system design.
• The interviewer may ask you to code on a shared platform (e.g., Microsoft Teams, Skype, or a collaborative coding editor).
• You may also be asked behavioral questions about your past projects, teamwork, and problem-solving approach.

1. On-site/Virtual Final Interview

• This is the most comprehensive stage, consisting of 4-5 interviews that last an entire day, either virtually or on-site at a Microsoft office.
• Each interview typically lasts 45-60 minutes and includes:
  • Coding interviews: More in-depth questions about algorithms, data structures, dynamic programming, recursion, etc.
  • System Design interviews: You may be asked to design a system or a component, focusing on scalability, maintainability, and performance.
  • Behavioral interviews: Expect questions related to Microsoft's core values, your experiences in past teams, dealing with conflict, leadership, and growth mindset.

Given a binary tree, write a function to check if it is a valid binary search tree (BST).