In my role as VP Global Talent Acquisition for Amazon, I trained Amazon interviewers on how to interview. This training consisted of competency-based behavioral interviewing techniques. Yet many candidates never got to the final round of interviews due to failing initial tech interviews. The rules for the technical interview are very different from standard interviewing. So you need to be prepared in advance for your tech interview. These rules apply for Amazon, Google, Apple, Facebook, Microsoft, Oracle and other tech employers.
Start your prep by reading and re-reading all of the information you can get your hands on regarding algorithms. Many tech questions are based on algorithms, not specific languages. If you took a course on algorithms, review all of your course material. If not, review all of the information you can find on algorithms. Next, study data structures. You will need to have at least one language where you have a level of mastery. Two or more would be even better so that you can select the one that matches up best with your interviewer. However, don't worry if the interviewer is not familiar with the specific language you use to solve a technical problem, it's the algorithms and data structures they will be looking at in your answer. Ideally, use an object oriented language in your problem solving.
Practice coding answers to possible questions in advance. Sites like Glassdoor and Leetcode have plenty of practice coding questions from a variety of tech employers. Work on practice answers in advance, but don’t depend on these specific answers to use in the interview. These practice answers are simply to get you ready to solve unique problems in the interview. Keep in mind that a good interviewer will often change a variable or two to ask how it will impact your answer or your ability to solve the problem. So the advanced practice helps you to be more nimble and agile in the actual interview.
If you are doing an in-person interview, be ready to whiteboard an answer. But don’t just write, talk. You need to talk as you write out your answer to show your logic in working out your answer to the problem. The tech interview evaluation is not only on the answer, but how you got to the answer. Even if the interviewer has not suggested that you use a whiteboard to solve the problem, almost every interview room has one. If there is one in the interview room, ask if you can use the whiteboard to solve the problem. If you are doing a phone interview, you might be asked in advance to either install whiteboarding software or visit a specific URL where you can whiteboard an answer.
Ideally, use specific examples of work you have done before to show not just how you would solve a problem, but how you have solved a similar problem in the past. Use the S-T-A-R behavioral approach, giving a Situation or Task, the Action you took and the Results achieved. Try to stay away from hypotheticals and use real life examples whenever possible.
Close the interview by asking about next steps, then follow up to make sure those next steps take place.
The technical interview is often a gating interview before the final round of interviews. While the tech interview by itself may not determine who gets hired, it can screen you out from being hired.