I applied online and was contacted a few weeks later to schedule a phone interview.

I went through two rounds of phone interviews, with two engineers each time. I don't know if it was planned this way or not, but for both rounds of interviews, the initial interview was with a really encouraging and motivational engineer, followed by a more distant and serious individual. It kind of threw me off my game, going from the "yeah, I got this" to "where did I mess up?" mindset.

In the end, I had a great experience interviewing with American Express. The engineers had more enthusiasm than at other places I had interviewed, and did not come across as brand ambassadors. They also answered questions candidly. I found a lot to respect.

The questions ranged from simple to more difficult. They also included behavioral, technical, and brain teasers.

Some examples included:

• What is the difference between a process and a thread?
• The knapsack problem reduced.
• The traveling salesman problem reduced to a subset of cities.
• How would you design a food rating application?