Overall, the interview process for Wealthfront was thorough and iterative, but also had the capacity to move extremely fast at the later stages.

I applied through university recruiting, which led to a sanity-check phone screen, then a technical phone screen, then a multi-part interview that was a mix of technical, behavioral, panel, and 1:1 meetings, then a 1:1 interview, and finally an on-site meeting. I met with a variety of engineers who all asked unique problems -- some with obvious but inefficient solutions, some with non-obvious solutions, and some with non-obvious edge cases. Be sure to think about these.

I was surprised at the number of steps involved in getting from start to end, but once you get there, you really see why. This is a lean startup of brilliant and impactful individuals, and they take great care about hiring their interns. They are treating their growth cautiously and trying their hardest to maintain quality while expanding.

The process was long, but there was a clear sense of drive among all the people I met. The interviews themselves were a mix between more algorithmic questions focused on data structures and complexity, to some more abstract and practical implementation tasks. The interviewers challenged you and tried to push you, so many times it felt like an uphill battle. I believe the purpose is to see how applicants struggle through tough problems. That makes sense, as the company is built on solving tough engineering problems.

TL;DR: Tough, but rewarding process. A mix of practical, abstract, and algorithmic problems.

Modify an existing data structure Y to add X new feature, running with a specific (or heavily implied) runtime complexity.

Some atypical search questions came up, not knowledge-based, more about problem-solving.