Software Engineer Interview Experience

# Problem Statement: Dynamic Product Queue Design a data structure that maintains a list of integers and supports efficient product calculation. The structure follows a **First-In-First-Out (FIFO)** eviction policy. --- ### Functional Requirements | Method | Description | | :--- | :--- | | **`insert(x: int)`** | Adds a new integer `x` to the end of the list. | | **`query() -> int`** | Returns the product of **all** current elements in the list. | | **`evict()`** | Removes the **oldest** element currently in the list. | --- ### Constraints & Goals * **Efficiency:** The product should not be recalculated from scratch during every `query` or `insert`. Aim for $O(1)$ time complexity for all operations where possible. * **The Zero Problem:** The solution must correctly handle the presence of `0`, which nullifies the product, and ensure the product recovers correctly once the zero is evicted. * **Precision:** If implementing in a language with fixed-size integers, consider potential overflow. (In Python, this is less of a concern due to arbitrary-precision integers). --- ### Implementation Template ```python from collections import deque class ProductList: def __init__(self): """ Initialize the data structure. """ self.product = 1 self.queue = deque() self.zero_count = 0 def insert(self, x: int) -> None: """ Adds an element to the stream. """ pass def query(self) -> int: """ Returns the product of all elements in the queue. """ pass def evict(self) -> None: """ Removes the oldest element from the queue. """ pass ``` --- ### Example Walkthrough 1. **Insert(2)**: List = `[2]`, Product = **2** 2. **Insert(5)**: List = `[2, 5]`, Product = **10** 3. **Insert(0)**: List = `[2, 5, 0]`, Product = **0** 4. **Insert(3)**: List = `[2, 5, 0, 3]`, Product = **0** 5. **Evict()**: Removes `2`. List = `[5, 0, 3]`, Product = **0** 6. **Evict()**: Removes `5`. List = `[0, 3]`, Product = **0** 7. **Evict()**: Removes `0`. List = `[3]`, Product = **3**

class Productlist: def __init__(self) -> None: self.computed = 1 self.index = 0 self.zeroTracker = deque() self.numberStream = deque() # 4 -> 3 -> # the zero is a sort of time bomb # O(1) def insert(self, x: int) -> None: if x != 0: self.computed *= x self.index += 1 else: self.computed = 1 self.zeroTracker.append(self.index) self.index = 0 self.numberStream.append(x) # O(1) def query(self) -> int: if len(self.zeroTracker) > 0: return 0 return self.computed # O(1) def evict(self) -> None: if len(self.zeroTracker) == 0: self.computed = self.computed // self.numberStream[0] self.numberStream.popleft() return front = self.zeroTracker[0] if front == 0: self.zeroTracker.popleft() else: self.zeroTracker[0] -= 1 self.numberStream.popleft()

What is your favourite programming language and why?

Describe a situation where you were given an ambiguous task or vague instructions. How did you go about clarifying the expectations to ensure the project stayed on track?