Code review in pull requests in Git - Time & Space Complexity

Time Complexity: Code review in pull requests

O(n)

Understanding Time Complexity

When reviewing code in pull requests, it's important to understand how the time to review grows as the amount of code changes increases.

We want to know: How does the effort scale when more files or lines are changed?

Scenario Under Consideration

Analyze the time complexity of this git command sequence used during code review.

git fetch origin

git checkout -b review-branch origin/feature-branch

git diff origin/main...review-branch

# Review changes line by line

This snippet fetches the latest code, creates a local branch for review, and shows the differences to be reviewed.

Identify Repeating Operations

Look for repeated work when reviewing code changes.

• Primary operation: Reading and analyzing each changed line in the diff output.
• How many times: Once per changed line, repeated for all lines changed in the pull request.

How Execution Grows With Input

The time to review grows as the number of changed lines grows.

Input Size (changed lines)	Approx. Operations (lines reviewed)
10	10 lines read and checked
100	100 lines read and checked
1000	1000 lines read and checked

Pattern observation: The review time grows directly with the number of changed lines.

Final Time Complexity

Time Complexity: O(n)

This means the time to review increases in a straight line as the number of changed lines grows.

Common Mistake

[X] Wrong: "Reviewing a pull request with many small commits is faster than one big commit with the same total changes."

[OK] Correct: The total lines changed matter most, not how they are split into commits; the reviewer still reads all changed lines.

Interview Connect

Understanding how review time scales helps you manage code quality and team workflow efficiently, a valuable skill in real projects.

Self-Check

"What if the pull request includes many binary files instead of text files? How would the time complexity of review change?"