Algorithm questions were asked. Just like typical LeetCode. Study that and time complexity for different algorithms.
OOP questions also
Study these and you should be fine
Aside from that maybe read up about the position and the product team that you would be working on.
The topics included algorithms related to sorting and data structures.
The following metrics were computed from 1 interview experience for the JetBrains SWE Intern role in Germany.
JetBrains's interview process for their SWE Intern roles in Germany is extremely selective, failing the vast majority of engineers.
Candidates reported having mixed feelings for JetBrains's SWE Intern interview process in Germany.