Amazon Software Development Engineer (SDE) interview questions

They asked me to design an efficient algorithm to find the longest substring without repeating characters, explain its time and space complexity, and then optimize it further if possible — testing both my coding and problem-solving approach.

Algorithm & Coding: “Find the longest substring without repeating characters.” “Merge k sorted linked lists.” “Implement an LRU cache.” “Given a binary tree, return its level order traversal.” “Find the kth largest element in a stream.” Design & System Thinking: “Design a URL shortener like TinyURL.” “Design a scalable notification system that supports millions of users.” “How would you use design patterns like Singleton or Observer in a real project?” “How do you ensure fault tolerance and scalability in a distributed system?” Behavioral / Teamwork: “Tell me about a time you disagreed with a teammate — how did you handle it?” “Describe a time you took ownership of a problem beyond your scope.” “Give an example of when you delivered under tight deadlines.” “Tell me about a time you improved a process or system in your team.”