Software Development Engineer, AWS Hyperplane

Amazon

You are given an array of servers represented by their processing power. You want to join consecutive servers together to form larger, more powerful servers. You can only join server i with server i+1 if the processing power of server i+1 is strictly greater than the processing power of server i. This joining process can cascade, meaning that if you join i and i+1, and the new combined processing power is less than i+2, you can then join the combined server with i+2, and so on. The goal is to maximize the number of these larger servers. For example: Consider the array [1, 2, 3, 4, 5]. You can join 1 and 2 to form 3. Then you can join 3 and 3 to form 6. Then you can join 6 and 4 to form 10. Finally, you can join 10 and 5 to form 15, resulting in one server with processing power 15. Consider the array [5, 4, 3, 2, 1]. You cannot join any servers because the processing power is always decreasing. Consider the array [1, 3, 2, 4, 1, 5]. You can join 1 and 3 to get 4. You cannot join 4 and 2. You can join 2 and 4 to get 6. You cannot join 6 and 1. You can join 1 and 5 to get 6. The final servers will be [4, 6, 6]. Write a function that takes an array of integers representing server processing powers and returns the final array of server processing powers after performing all possible joins.

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

Describe a time when a plan did not go as expected.