Ours vs theirs in conflicts in Git - Performance Comparison

Time Complexity: Ours vs theirs in conflicts

O(n)

Understanding Time Complexity

When resolving conflicts in git, we often choose between "ours" and "theirs" changes. Understanding how the time to resolve conflicts grows helps us manage bigger projects smoothly.

We want to know how the effort scales as the number of conflicting files or changes increases.

Scenario Under Consideration

Analyze the time complexity of this git conflict resolution snippet.

# Assume multiple conflicting files
for file in $(git diff --name-only --diff-filter=U); do
  git checkout --ours "$file"
  git add "$file"
done

This script loops over all files with conflicts, chooses "ours" version for each, and stages them.

Identify Repeating Operations

Identify the loops, recursion, array traversals that repeat.

• Primary operation: Looping over each conflicting file and running git commands on it.
• How many times: Once per conflicting file, so the number of conflicts determines the count.

How Execution Grows With Input

As the number of conflicting files grows, the total commands run grow linearly.

Input Size (n)	Approx. Operations
10 conflicts	About 20 git commands (checkout + add per file)
100 conflicts	About 200 git commands
1000 conflicts	About 2000 git commands

Pattern observation: The work grows directly with the number of conflicts; doubling conflicts doubles the commands.

Final Time Complexity

Time Complexity: O(n)

This means the time to resolve conflicts by choosing "ours" grows linearly with the number of conflicting files.

Common Mistake

[X] Wrong: "Resolving conflicts with 'ours' or 'theirs' is instant no matter how many files conflict."

[OK] Correct: Each conflicting file requires a separate command to resolve and stage, so more conflicts mean more work and time.

Interview Connect

Understanding how conflict resolution scales shows you grasp practical git workflows. This skill helps you manage merges smoothly in real projects, a valuable ability for any developer.

Self-Check

What if we changed the script to resolve conflicts in parallel instead of one by one? How would the time complexity change?

Practice

1. In a Git merge conflict, what does ours refer to?

easy

A. A backup copy of the file before the merge

B. The version of the file in the branch you are merging

C. The common ancestor version of the file

D. The version of the file in your current branch

Solution

1. Step 1: Understand the meaning of 'ours' in Git conflicts

   'Ours' means the version of the file in your current branch where you started the merge.

2. Step 2: Differentiate from 'theirs'

   'Theirs' refers to the version from the branch you are merging into your current branch.

3. Final Answer:

   The version of the file in your current branch -> Option D

4. Quick Check:

   Ours = current branch version [OK]

Hint: Ours = your branch, theirs = merging branch [OK]

Common Mistakes:

• Confusing 'ours' with 'theirs'
• Thinking 'ours' means the common ancestor
• Assuming 'ours' is a backup copy

2. Which Git command correctly chooses the 'theirs' version of a conflicted file named app.js?

easy

A. git checkout --ours app.js

B. git checkout --theirs app.js

C. git reset --theirs app.js

D. git merge --theirs app.js

Solution

1. Step 1: Identify the correct command to pick 'theirs'

   The command to choose the 'theirs' version during conflict is git checkout --theirs <file>.

2. Step 2: Verify the file name usage

   Using app.js after the command specifies the file to resolve.

3. Final Answer:

   git checkout --theirs app.js -> Option B

4. Quick Check:

   Use 'git checkout --theirs' to pick theirs [OK]

Hint: Use 'git checkout --theirs <file>' to pick theirs version [OK]

Common Mistakes:

• Using 'git reset' instead of 'git checkout'
• Confusing '--ours' with '--theirs'
• Trying 'git merge --theirs' which is invalid

3. After a merge conflict on index.html, you run:
git checkout --ours index.html
What will be the content of index.html after this command?

medium

A. The version from your current branch before the merge

B. The version from the branch you are merging

C. The common ancestor version

D. An empty file

Solution

1. Step 1: Understand what 'git checkout --ours' does in conflict

   This command replaces the conflicted file with the version from your current branch before the merge.

2. Step 2: Confirm the file content after the command

   After running it, index.html will have your branch's original content, ignoring the other branch's changes.

3. Final Answer:

   The version from your current branch before the merge -> Option A

4. Quick Check:

   'git checkout --ours' = current branch content [OK]

Hint: Checkout --ours picks your branch's file version [OK]

Common Mistakes:

• Thinking it picks the other branch's version
• Assuming it resets to common ancestor
• Expecting it to merge both versions automatically

4. You tried to resolve a conflict by running git checkout --theirs main.js but the file did not update. What is the likely cause?

medium

A. You need to commit before checking out

B. You used the wrong file name

C. You are not in a conflicted merge state

D. The command only works after resolving conflicts manually

Solution

1. Step 1: Check the merge state requirement

   The git checkout --theirs command only works when Git detects a conflict during a merge.

2. Step 2: Understand why the file didn't update

   If you are not in a conflicted state, Git has no 'theirs' version to apply, so the file stays unchanged.

3. Final Answer:

   You are not in a conflicted merge state -> Option C

4. Quick Check:

   'git checkout --theirs' needs conflict state [OK]

Hint: Use 'git status' to confirm conflict before checkout --theirs [OK]

Common Mistakes:

• Trying to use --theirs outside a merge conflict
• Assuming checkout updates file without conflict
• Not verifying current branch or file name

5. During a complex merge conflict involving multiple files, you want to keep your current branch's version for config.yaml but accept the other branch's version for README.md. Which sequence of commands correctly resolves this?

hard

A. git checkout --ours config.yaml && git checkout --theirs README.md && git add config.yaml README.md

B. git checkout --theirs config.yaml && git checkout --ours README.md && git add config.yaml README.md

C. git reset --ours config.yaml && git reset --theirs README.md && git commit -m 'Resolve conflicts'

D. git merge --ours config.yaml README.md

Solution

1. Step 1: Use correct commands to pick versions per file

   To keep your branch's version for config.yaml, use git checkout --ours config.yaml. To accept the other branch's version for README.md, use git checkout --theirs README.md.

2. Step 2: Stage the resolved files

   After choosing versions, add both files to the staging area with git add config.yaml README.md to mark conflicts resolved.

3. Final Answer:

   git checkout --ours config.yaml && git checkout --theirs README.md && git add config.yaml README.md -> Option A

4. Quick Check:

   Use checkout --ours/theirs per file, then git add [OK]

Hint: Pick versions per file with checkout, then git add to resolve [OK]

Common Mistakes:

• Mixing up --ours and --theirs for files
• Forgetting to git add after checkout
• Using git reset or git merge incorrectly