Practice Code Maintenance in CS Thinking

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

The ongoing process of updating, fixing, and improving software after its initial release to correct bugs, adapt to new requirements, improve performance, and keep dependencies current. Maintenance includes four types: corrective (fixing bugs), adaptive (adapting to new environments), perfective (improving functionality), and preventive (reducing future problems).

Software is never 'done.' Like a garden, it needs constant tending — fixing bugs, updating dependencies, and adapting to changing needs.

Showing a random 20 of 50 problems.

Example 1

easy
Classify: a user reports a crash when uploading a 5 GB file. The fix that handles it is ____ maintenance.

Example 2

easy
Why are meaningful variable names a maintenance practice?

Example 3

medium
A function getCustomerById is renamed. List one risk and one mitigation.

Example 4

medium
Why is writing maintainable code from the START economically smart, given the 60-80% rule?

Example 5

hard
A legacy module has no tests and produces correct output. Outline the safe order of work to add a new feature inside it.

Example 6

easy
Before changing unfamiliar code, what should you do first to avoid introducing bugs?

Example 7

medium
Why are small, frequent commits easier to maintain than one huge end-of-week commit?

Example 8

easy
Fixing a reported bug in released software is which type of maintenance?

Example 9

easy
Roughly what share of software's total lifetime cost does maintenance typically consume?

Example 10

easy
Roughly what fraction of total software cost is maintenance?

Example 11

challenge
Maintenance backlog has: (1) a data-loss bug, (2) a nice-to-have feature, (3) an unpatched critical CVE. Order by priority and justify the top item.

Example 12

medium
A test that fails sometimes and passes other times without code changes is called ____.

Example 13

medium
A library you depend on has a critical security patch released. Which maintenance type and action?

Example 14

hard
Explain the term 'technical debt' and give two examples of how it accumulates. How does it affect long-term code maintenance?

Example 15

easy
What is a 'magic number' and why is it a maintenance risk?

Example 16

easy
Name the four types of software maintenance.

Example 17

easy
Why update dependencies regularly? (best reason)

Example 18

hard
Two engineers fix the same bug by editing the same lines on separate branches. What is the standard term for the conflict, and what is the resolution discipline?

Example 19

challenge
A team is asked: 'rewrite or refactor this 10-year-old monolith?'. State the principle that biases the answer.

Example 20

medium
A team faces a messy module. Option A: incremental refactor with tests. Option B: full rewrite. Which is generally safer?
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