SIG (Susquehanna) Interview Questions — Page 4

SIG (Susquehanna)·Software Engineer·Technical Phone Screen

May 2026

SIG coding round, pretty much all matrix manipulation in Python. One question but it had four parts and they wanted working code plus example outputs for each. Not the most complex stuff algorithmically but you need to be precise and not fumble the indexing.

Given a 3x3 matrix, write Python code to: (a) transpose it in-place, (b) swap two specified rows and two specified columns, (c) reverse a specified column and reverse all rows, and (d) rotate the matrix 90 degrees clockwise. Show example inputs and outputs for each part.

“Four parts sounds manageable until you're live coding and realize your in-place transpose is clobbering values before you swap them.”

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SIG (Susquehanna)·Data Scientist·Technical Phone Screen

May 2026

SIG (Susquehanna) threw a logic puzzle at me for a Data Scientist screen and it was the kind of thing that looks clean on paper until you're actually in it. One question, pure reasoning, no coding.

Three people (Asta, Bronya, and Clara) each have a different number of cats. Each person tells the truth when speaking to someone with fewer cats than them, and lies when speaking to someone with more cats. Given four statements they make to each other, and knowing not all statements are true, figure out how many cats Asta has.

“This one took me way longer than I'd like to admit.”

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SIG (Susquehanna)·Software Engineer·Online Assessment (OA)

May 2026

Two coding problems for a SWE role at Sig. The theater seating one was more involved than it looked, and the ticker extraction problem had enough edge cases to keep things interesting for a while.

Given n rows in a movie theater where each row has seats 1 through 10, and a list of already-reserved seats, return the maximum number of 4-person groups that can be seated together. A group must occupy one of three contiguous blocks: seats 2-5, 4-7, or 6-9.
Given a news headline and a dictionary mapping stock tickers to lists of company name aliases or keyword phrases, write a function that returns all tickers mentioned in the headline, in order of first appearance, case-insensitively, ignoring punctuation, with whole-word matching and a preference for longer phrases when aliases overlap at the same position.

“The overlap between blocks is what gets you.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

May 2026

Quant researcher interview at Sig with a probability question built around a table of bookstore profit data. Pretty niche setup but the underlying concept is just conditional probability, which I should have been more comfortable with.

You're given a table of annual profits by sector at a university bookstore across multiple years. If you sample a single (sector, year) cell uniformly at random and the profit in that cell exceeds $8,000, what's the probability the year was 2019?

“Blanked for a second on how to set it up.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

May 2026

Interviewed for a quant researcher role at SIG. One probability question, classic Bayesian setup. Pretty standard for this kind of shop but still easy to fumble if you rush it.

Factory A produces 40% red and 60% black widgets. Factory B produces 80% red and 20% black. A factory is chosen at random, then two widgets are drawn from it. Both come out black. What's the probability they came from Factory A?

“Bayes all the way.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

May 2026

SIG quant researcher interview with a combinatorics/probability question on a small custom deck. Pretty clean problem but the calculation has a few moving parts if you're not careful about how you count pairs.

You have a 10-card deck with exactly two cards of each of five ranks (10, J, Q, K, A). You're dealt 5 cards without replacement. What is the expected number of pairs in your hand?

“Linearity of expectation saves you here, which I didn't immediately reach for.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

May 2026

SIG quant researcher interview with a combinatorics seating puzzle. Pretty niche problem that felt more like a math olympiad warmup than anything I'd seen in prep materials.

Five toddlers (Anna, Brian, Charlie, Dixie, Eva) need to be seated at a round table with the following constraints: Anna won't sit next to Brian or Eva, Brian won't sit next to Charlie, and Dixie won't sit next to Eva or Charlie. Given that Dixie sits immediately to the left of Anna, and Anna sits immediately to the left of Brian, who sits immediately to the left of Brian?

“I stared at this for an embarrassingly long time.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

May 2026

Quant Engineer interview at SIG, probability and statistics heavy. The dice problem sounds textbook until you're actually sitting there trying to remember how to derive variance from scratch under pressure.

Given two fair six-sided dice, what is the probability that their sum equals some value k? Give a general formula, and walk through the expected value and variance of the sum.

“The counting part was fine, I drew out the triangle distribution in my head and got through the formula okay.”

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SIG (Susquehanna)·Data Scientist·Technical Phone Screen

May 2026

Interviewed for a Data Scientist role at SIG and got hit with a classic knights and knaves logic puzzle. Pretty representative of the kind of lateral thinking they seem to value there.

On an island of knights (always truthful) and knaves (always lying), person B says to person A: 'You always lie.' Which role assignments are logically consistent, and why?

“I stared at this for a second because it looks simple but you have to be careful about each case.”

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SIG (Susquehanna)·Software Engineer·Technical Phone Screen

Jun 2026

SIG quant engineer interview with a probability/expected value question. Pretty classic for the firm but still takes a second to set up cleanly if you haven't drilled this type recently.

Roll a fair 6-sided die twice. If the two results are different, you win the higher of the two values in dollars. If they match, you win nothing. What is the expected payout?

“You have to enumerate carefully here.”

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