Amazon Software Engineer interview questions

First got interest by applying in person during a career fair and handing one of their employees a resume and talking to them briefly. I was given a pre-screen question, sometimes it's hit or miss, but they're generally quick questions you can reason out quickly if you've been prepping for interviews in general. They usually ask for a bit of code on paper or a algorithm/data structures question verbally when you hand them your resume, then a 1:1 interview or phone screen. Didn't get further than that. Afterwards, if you pass the first round, it's final round interviews on their campus.

I was contacted by an Amazon recruiter for a position that would involving refactoring existing code from C/C++ to Java and other technologies for internal use as well as tools for customer (seller) use. The technical interview was challenging but nothing a competent software engineer shouldn't be at least familiar with. Big O notation, data structures (specifically trees, binary trees, and tree searching algorithms) are a must to confidently proceed.