Sr. Software Development Engineer, US Amazon Dedicated Cloud Security

Amazon

There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid0). The robot tries to move to the bottom-right corner (i.e., gridm - 1). The robot can only move either down or right at any point in time. Given the two integers m and n, return the number of possible unique paths that the robot can take to reach the bottom-right corner. The test cases are generated so that the answer will be less than or equal to 2 * 109. For example, if m = 3 and n = 7, the expected output is 28. Explain your approach, provide code, and analyze the time and space complexity. Also discuss edge cases and alternative solutions using combinatorics.

Amazon

Let's design a turnstile. A turnstile is a type of gate which allows one person to pass at a time. Consider a turnstile at a subway station. There are two panels that rotate to allow a single person passage. The turnstile has two states, Locked and Unlocked, and the customer can either Push the turnstile or Insert a token/card. Here is the state transition table: | Event | Current State | Action | Next State | | :----- | :------------ | :------------- | :--------- | | Push | Locked | | Locked | | Token | Locked | Unlock | Unlocked | | Push | Unlocked | Pass through | Locked | | Token | Unlocked | (discarded) | Unlocked | Requirements: Model the state and behavior of a simple turnstile. Implement two methods: insert_token() push() Consider edge cases and error handling. What happens if someone tries to push without inserting a token? What happens if the system malfunctions? Example: turnstile = Turnstile() print(turnstile.state) # Output: Locked turnstile.push() print(turnstile.state) # Output: Locked turnstile.insert_token() print(turnstile.state) # Output: Unlocked turnstile.push() print(turnstile.state) # Output: Locked How would you approach this design and implementation, keeping in mind scalability, maintainability, and potential future extensions such as different types of tokens or remote unlocking?

Amazon

Tell me about yourself. To give you some guidance, please share information beyond just your resume. For example, what are you passionate about, what motivates you, and what are some of your long-term career goals? Think about some significant accomplishments you are proud of and how those experiences have shaped you. What makes you a unique candidate and a good fit for our company, beyond your technical skills? I'm looking for a comprehensive overview of who you are, both professionally and personally.