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What difficulty level is this coding question?

This is a hard difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Amazon.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Amazon during technical interviews.

Implement array and tree traversal tasks

Quick Overview

This question evaluates algorithmic problem-solving and data-structure competency, specifically array-based optimization for single-trade profit and tree traversal techniques for right-side view, along with time/space complexity analysis and system-level considerations; the domain is Coding & Algorithms.

Company: Amazon

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: hard

Interview Round: Technical Screen

You are interviewing for a storage/infra-leaning role. Solve the following coding tasks and be ready to discuss time/space complexity and edge cases. ## Task A: Max profit from one trade Given an integer array `prices` where `prices[i]` is the price of a stock on day `i`, compute the maximum profit achievable by choosing **at most one** buy day `b` and one sell day `s` with `b < s`. If no profit is possible, return `0`. - **Input:** `prices: int[]` - **Output:** `max_profit: int` - **Constraints (typical):** `1 <= n <= 2e5`, prices fit in 32-bit int **Follow-ups:** - What is the best achievable time and space complexity? - How do you handle monotonically decreasing prices? ## Task B: Right-side view of a binary tree Given the root of a binary tree, return the list of node values visible when the tree is viewed from the right side (from top level to bottom level). - **Input:** `root` (binary tree node) - **Output:** `right_view: int[]` **Follow-ups:** - Compare DFS vs BFS approaches and their complexities. - What are edge cases (empty tree, skewed tree, very deep tree)? ## Discussion (no coding required, but explain clearly) - If the code were used in a **multi-threaded** environment or under **very large datasets**, what assumptions break and what changes (if any) would you make?

Quick Answer: This question evaluates algorithmic problem-solving and data-structure competency, specifically array-based optimization for single-trade profit and tree traversal techniques for right-side view, along with time/space complexity analysis and system-level considerations; the domain is Coding & Algorithms.

Max Profit from One Stock Trade

Return the maximum profit from at most one buy before one sell.

Constraints

Inputs are provided as Python literals matching the function signature.
Return a deterministic exact-match result.

Examples

Input: ([7,1,5,3,6,4],)

Expected Output: 5

Explanation: Buy at 1 sell at 6.

Input: ([7,6,4,3,1],)

Expected Output: 0

Explanation: No profit.

Input: ([5],)

Expected Output: 0

Explanation: Single price.

Hints

Choose a representation that makes the core operation simple.
Handle empty and boundary inputs before the main algorithm.

Right Side View of a Binary Tree

Given a binary tree as level-order values with None holes, return the visible node values from the right side.

Constraints

Inputs are provided as Python literals matching the function signature.
Return a deterministic exact-match result.

Examples

Input: ([1,2,3,None,5,None,4],)

Expected Output: [1, 3, 4]

Explanation: Classic right view.

Input: ([],)

Expected Output: []

Explanation: Empty tree.

Input: ([1,None,2,None,None,3],)

Expected Output: [1, 2, 3]

Explanation: Right skew represented in level order.

Hints

Choose a representation that makes the core operation simple.
Handle empty and boundary inputs before the main algorithm.

Quick Overview