PRACTICE GUIDE OLD MISSION
Old Mission Coding Problem Practice Test
Outcry’s Old Mission coding problem practice section has 1 questions in 25 minutes. These numbers describe the linked mock; the source check below distinguishes published details from practice settings.
The two clocks, question mix, language, navigation and scoring are Outcry settings, not a verified universal Old Mission screen.
Outcry is not affiliated with Old Mission and has no access to their assessment content. This guide describes an assessment format that candidates report publicly; the questions here are generated by Outcry and are not Old Mission’s own.
What it screens
A Chicago-based options market maker and hedging firm trading listed derivatives across global exchanges.
- ✓Reading concurrent code and pointing at the defective line
- ✓Order-book data structures: what happens on a cross, a cancel, a partial fill
- ✓Algorithmic complexity chosen for the input sizes stated in the problem
- ✓Monte Carlo methods and when a simulation beats a closed form
Where it sits at Old Mission
No current firm-published specification for this exact 25-question quantitative and one-question coding combination was verified.
Practice stage: Quantitative & coding practice · round unconfirmed. The two clocks, question mix, language, navigation and scoring are Outcry settings, not a verified universal Old Mission screen.
The format
These are the settings used by Outcry’s Old Mission practice sitting. They are not automatically the employer’s published format; see the linked assessment’s source check.
| Questions | 1 |
|---|---|
| Time | 25 minutes |
| Per question | 25 minutes |
| Negative marking | No |
| Answer style | Code editor, run against hidden tests |
| Where it sits | Quantitative & coding practice · round unconfirmed |
What it tests, with a worked example
Every example below is generated by Outcry, drawn from the same question generators the timed drills run. None of them is Old Mission’s.
Complexity that is actually graded
Hidden tests sized so the naive solution times out. A correct answer that is too slow scores the same as a wrong one.
Reading someone else's code
A diff or a function with a bug in it, and the question is where.
Example
A lock-free SPSC ring buffer publishes its head index with memory_order_relaxed. What can go wrong?
- The index can wrap incorrectly
- The consumer may see the new index before the slot's data is visible
- The producer may block
- Nothing - SPSC needs no ordering
Answer The consumer may see the new index before the slot's data is visible
The publishing store needs release semantics to pair with the consumer's acquire load, or the buffer write can be reordered after it.
Language and systems detail
Memory, references, undefined behaviour and the things that bite in production.
Example
What is the solution to T(n) = T(n/2) + n^2?
- Theta(log n)
- Theta(n^3 log n)
- Theta(n^3)
- Theta(n^2)
Answer Theta(n^2)
log_2(1) = 0 and the driving term is n^2. 2 beats 0, so the top-level work dominates and the answer is n^2.
Numerical and data handling
Floating point, aggregation and joins on data that does not fit the obvious shape.
Example
A price walks on the whole numbers 0 to N. Each step it moves +1 with probability p and -1 with probability 1 - p, independently. It stops the first time it touches 0 or N. N = 8 start = 4 p = 0.6 One question, six parts. Each part uses the part before it.
Part 3 of 6. Now use p = 0.6. What is the probability the walk stops at N?
Answer 0.8350515463917525
With drift the answer is (1 - r^start)/(1 - r^N) where r = (1-p)/p = 0.6667. That is (1 - 0.1975) / (1 - 0.039) = 0.8351. Part 1 gave 0.5, so the drift is worth 0.3351 here.
Edge cases
Empty input, one element, duplicates and overflow. The hidden tests always include them.
Reading a spec precisely
Return type, ordering and tie-breaking are graded, and are where most silent failures come from.
What a good score looks like
Use this mock’s score and worked review to identify skills to practise. No Outcry score guarantees a pass or a hiring outcome; a current employer threshold for this practice paper has not been verified.
How to train for it
- 01Implement the core structures from scratch once each. The screens ask you to build them, not use them.
- 02Get the function signature exactly right before anything else. Return type and ordering are graded, and a correct algorithm behind a wrong signature scores zero.
- 03Practise without an autocomplete. The screens run in a bare editor, and the gap between writing code with help and without it is larger than most people expect.
TRAIN IT HERE
The drills that match each section
Concurrency Clash
Find the data race, name the fix - real C++ defect patterns, five levels.
Order Book
Matching-engine mechanics: crosses, cancels and partial fills.
Algorithm Interview Track
DP tables, Monte Carlo estimation and speed rounds at four difficulty tiers.
SIT THE FULL BATTERY
All the sections back to back on one clock, marked the way the real screen marks them, with a by-skill breakdown at the end. Included with any pass.
Also reported at Old Mission
Common questions
- Is this Old Mission’s official coding problem test?
- No. Outcry generates its own questions. No current firm-published specification for this exact 25-question quantitative and one-question coding combination was verified. The two clocks, question mix, language, navigation and scoring are Outcry settings, not a verified universal Old Mission screen.
- How long is this coding problem practice section?
- 1 questions in 25 minutes in the Outcry mock. These are practice settings unless the source check explicitly confirms them.
- How is the practice marked?
- Correct answers earn 1 mark unless the question states another weight. Wrong answers lose 0; unanswered items lose 0, including timeouts. These rules apply to this mock.
- Where can I check the employer’s process?
- See the public source check on the linked assessment. Your role-specific invitation governs the actual format, permitted tools and scoring.