Two Sigma New Grad Software Engineer Interview Experience — Two OA Questions, Advanced the Next Day

I applied for Two Sigma's New Grad SWE role. I didn't have much hope going in — not long after a mass application round, I got an OA invite: two problems to solve together in one time-limited session.

Before applying I'd heard this company has a lot of rejection stories, so I specifically went and dug through the forum to do my homework. Several posts said the OA questions on the forum were the actual questions used. Treating it as a long shot, I searched up these problems ahead of time, so I went in with at least a little confidence.

The first question was IPO Share Allocation — given a bunch of bids (userId, shares, price, timestamp), allocate shares starting from the highest price downward, with ties at the same price broken by round-robin allocation based on timestamp.

When I was writing it, I initially missed the step of sorting the same-price group by timestamp before allocating and just allocated directly. Running the tests showed the result was wrong, and after going back and fixing it, it passed — but that left me with very little time remaining.

The second question was Split Drainage Tree (the forum calls it the "drainage" problem) — given a parent array representing a tree structure, where each node has a flow value, you need to cut one edge to split the tree into two halves so the flow difference between the two sides is minimized. This one wasn't too bad — I did a DFS to compute subtree sums and solved it, a lot easier than the first question.

I submitted both. I expected to wait a long while, but I got the email moving me to the next round the very next day — that moment felt genuinely good. I'd never specifically grinded interview experience posts before; this time I purely followed advice and dug through the forum, and it actually paid off. Felt like that bit of prep wasn't wasted.

Next up should be the phone interview, and I'm not sure if it'll be OOD or pure coding — a little nervous about it. Looking for pointers from anyone who's been through it on roughly what gets tested.