I got rejected on the take-home assignment, so I can't say too much for what comes next.

1. Hand-wavy conversation to see if you understand the big-O complexity of sorting algorithms.
2. Take-home assignment to build a variant of Tetris in your language of choice.

Overall, and compared to other firms in this industry, this is a hilariously poorly thought-out process from DRW. Take-home tests are negative experiences for candidates across the board because they are usually poorly specified and weigh so heavily on the candidate's efforts, and not at all on an interviewer's. If candidates are spending 2-4 hours on a submission, DRW interviewers should take that time to review it (not 20 minutes and going, "it doesn't run the way ours does, so fail"). The effort equilibrium is completely out of whack.

Given a galaxy and an arbitrary point in the galaxy, how would you find the K nearest stars?

Build a variant of Tetris where after clearing a line, shapes don't fall into empty spaces below (unless an entire line is cleared). Return the height of the tallest column of blocks at the end of a given set of pieces.