Groupon had a two-round interview process.

The first round consisted of two back-to-back, 45-minute on-campus interviews.

• One was a design question.
• One was an algorithms question.

They were pretty enjoyable. One of my interviewers had actually read my resume in-depth, checked out my GitHub, and asked some pretty interesting questions about projects and things I could have considered.

The second round involved three hour-long, back-to-back Skype interviews. These were definitely more challenging, but otherwise decent. As a freshman, I didn't know enough to answer some conceptual questions and struggled to implement some structures I was unfamiliar with. However, the overall difficulty was alright. The algorithms questions were certainly very solvable.

What is the difference between a hashtable and a hashmap in Java?