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Headlands C++ Problem Practice Test

Outcry’s Headlands c++ problem practice section has 1 questions in 20 minutes. These numbers describe the linked mock; the source check below distinguishes published details from practice settings.

Counts, clocks, item weights and answer styles are Outcry settings. Coding runs in JavaScript here; no claim is made that the live screen requires that language or these blocks.

Outcry is not affiliated with Headlands Technologies 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 Headlands Technologies’s own.

What it screens

A Chicago-based quantitative trading firm making markets in listed derivatives.

  • ✓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 Headlands Technologies

Headlands publishes quantitative research and software role requirements. This audit did not verify the exact four-block, 70-minute screen from a current primary source.

Practice stage: Research & coding practice · round unconfirmed. Counts, clocks, item weights and answer styles are Outcry settings. Coding runs in JavaScript here; no claim is made that the live screen requires that language or these blocks.

The format

These are the settings used by Outcry’s Headlands practice sitting. They are not automatically the employer’s published format; see the linked assessment’s source check.

Questions1
Time20 minutes
Per question20 minutes
Negative markingNo
Answer styleCode editor, run against hidden tests
Where it sitsResearch & 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 Headlands Technologies’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

Position is accumulated in a double and the code tests `if (position == 0.0)` to detect flat. What goes wrong?

  • Comparing doubles is undefined behaviour
  • The compiler removes the comparison
  • 0.0 and -0.0 compare unequal
  • Accumulated rounding leaves a residue, so the test is false when the book is flat

Answer Accumulated rounding leaves a residue, so the test is false when the book is flat

Adding and subtracting fills in binary leaves a residue around 1e-15. Compare against a tolerance, or hold size in integer lots and never in a double.

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.

Statistics in code

Rolling windows, correlations and quantiles, implemented rather than imported.

Example

A population has standard deviation 8. What is the variance of the mean of 25 independent draws?

  • 1600
  • 64
  • 2.56
  • 0.32

Answer 2.56

Var(X̄) = σ²/n = 8²/25 = 64/25 = 2.56. The three wrong options are the population variance 64 left undivided, the standard deviation over n rather than the variance, and 1,600 - the variance multiplied by n instead of divided by it.

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

  1. 01State the complexity before you write. If it is worse than the input size allows, the approach is already wrong.
  2. 02Write the edge cases into your own tests first. That is where the hidden ones live.
  3. 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

C++ PROBLEMFREE RUN

Concurrency Clash

Find the data race, name the fix - real C++ defect patterns, five levels.

C++ PROBLEMFREE RUN

Order Book

Matching-engine mechanics: crosses, cancels and partial fills.

C++ PROBLEMFREE RUN

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.

MOCK SCREENS

Also reported at Headlands Technologies

Common questions

Is this Headlands’s official c++ problem test?
No. Outcry generates its own questions. Headlands publishes quantitative research and software role requirements. This audit did not verify the exact four-block, 70-minute screen from a current primary source. Counts, clocks, item weights and answer styles are Outcry settings. Coding runs in JavaScript here; no claim is made that the live screen requires that language or these blocks.
How long is this c++ problem practice section?
1 questions in 20 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.