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Barclays·Software Engineer·Online Assessment (OA)·Junior

JuniorPrefer not to say
Sep 2026

Summary

Did the Barclays software engineer intern online assessment. Two coding questions, one embarrassingly easy and one that absolutely wrecked me.

Questions Asked (2)

Q1

First coding question on the technical assessment.

Algorithms & Data Structures
Author's notes

Knocked it out in under 30 seconds.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem statement and constraints, then discuss a brute-force solution before optimizing with appropriate data structures. Walk through your thought process, write clean code, and test with edge cases.

Pro tip: Communicate your reasoning clearly and check for edge cases like empty inputs or large data sizes; interviewers value problem-solving skills and code quality over just getting the right answer.

1. Understand the problem

Ask clarifying questions to confirm input format, output expectations, and constraints. Restate the problem in your own words to ensure alignment.

2. Explore approaches

Discuss a naive solution first, then analyze its time and space complexity. Propose optimizations using suitable data structures or algorithms.

3. Plan and code

Outline your chosen approach step-by-step, then write clean, modular code with meaningful variable names. Comment on key logic.

4. Test and validate

Walk through your code with sample inputs, including edge cases like empty input, single element, or large values. Fix any issues found.

5. Analyze complexity

State the final time and space complexity of your solution and discuss potential trade-offs or further optimizations.

Key Points to Mention

  • Clarify constraints and edge cases before coding
  • Start with a brute-force solution and then optimize
  • Use appropriate data structures (e.g., hash maps, arrays) for efficiency
  • Analyze time and space complexity of your solution
  • Write clean, readable code with meaningful names
  • Test with edge cases and walk through examples

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q2

Second coding question on the technical assessment.

Algorithms & Data Structures
Author's notes

This was a completely different beast.

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AI HintsAI Generated

Suggested Approach

Clarify the problem constraints and expected input/output before coding, then walk through a brute-force solution and optimize it using appropriate data structures. Verbalize your thought process, write clean modular code, and test with edge cases including empty inputs and large values.

Pro tip: In a banking context, mention how your solution handles large datasets and avoids integer overflow or precision issues—this shows you think beyond the algorithm. Also, explicitly state time and space complexity before the interviewer asks.

1. Clarify requirements and constraints

Ask about input size, data types, expected output format, and any edge cases like empty arrays or duplicate values. Confirm assumptions before writing any code.

2. Discuss a brute-force approach

Briefly outline the naive solution and its complexity to establish a baseline. This demonstrates structured thinking and gives you a fallback if optimization stalls.

3. Optimize with the right data structure or algorithm

Identify bottlenecks in the brute-force solution and propose improvements using hash maps, two pointers, sorting, or dynamic programming as appropriate. Explain the trade-offs.

4. Write clean, modular code

Implement the optimized solution with meaningful variable names and helper functions where useful. Keep the code readable and avoid premature micro-optimizations.

5. Test and analyze complexity

Walk through the code with a small example, then test edge cases. State the final time and space complexity and mention any potential improvements or trade-offs.

Key Points to Mention

  • Time and space complexity of both brute-force and optimized solutions
  • Choice of data structure (e.g., hash map for O(1) lookups) and why it fits the problem
  • Handling of edge cases such as empty input, single element, duplicates, and integer overflow
  • Trade-offs between readability, performance, and memory usage
  • How the solution would scale for large datasets typical in financial systems
  • Testing strategy including unit tests and boundary conditions

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.