Cherry-picking multiple commits in Git - Time & Space Complexity

Time Complexity: Cherry-picking multiple commits

O(n)

Understanding Time Complexity

When using git to cherry-pick multiple commits, it's important to understand how the time taken grows as you pick more commits.

We want to know how the work increases when applying several commits one after another.

Scenario Under Consideration

Analyze the time complexity of the following git commands.

git cherry-pick commit1 commit2 commit3
# or
for commit in commit1 commit2 commit3; do
  git cherry-pick $commit
 done

This code applies multiple commits one by one onto the current branch.

Identify Repeating Operations

• Primary operation: Each cherry-pick applies one commit.
• How many times: Once per commit being cherry-picked.

How Execution Grows With Input

Each additional commit adds one more cherry-pick operation, so the total work grows directly with the number of commits.

Input Size (n)	Approx. Operations
10 commits	10 cherry-pick operations
100 commits	100 cherry-pick operations
1000 commits	1000 cherry-pick operations

Pattern observation: The work increases steadily and linearly as you add more commits.

Final Time Complexity

Time Complexity: O(n)

This means the time to cherry-pick grows in direct proportion to the number of commits you apply.

Common Mistake

[X] Wrong: "Cherry-picking multiple commits is done all at once, so time stays the same no matter how many commits."

[OK] Correct: Each commit must be applied separately, so more commits mean more work and more time.

Interview Connect

Understanding how operations scale with input size shows you can think about efficiency in real tasks, like managing code changes with git.

Self-Check

"What if we cherry-pick a range of commits using a single command instead of one by one? How would the time complexity change?"

Practice

1. What does the git cherry-pick command do when used with multiple commit hashes?

easy

A. It applies the changes from each specified commit onto the current branch.

B. It merges the entire branch containing those commits into the current branch.

C. It deletes the specified commits from the current branch.

D. It creates a new branch with the specified commits only.

Solution

1. Step 1: Understand cherry-pick purpose

   The git cherry-pick command copies changes from specific commits to the current branch without merging the whole branch.

2. Step 2: Effect of multiple commits

   When multiple commit hashes are listed, git applies each commit's changes one by one onto the current branch.

3. Final Answer:

   It applies the changes from each specified commit onto the current branch. -> Option A

4. Quick Check:

   Cherry-pick = copy specific commits [OK]

Hint: Cherry-pick copies commits, it does NOT merge branches [OK]

Common Mistakes:

• Confusing cherry-pick with merge
• Thinking it deletes commits
• Assuming it creates a new branch

2. Which of the following is the correct syntax to cherry-pick multiple commits with hashes a1b2c3 and d4e5f6?

easy

A. git cherry-pick --all a1b2c3 d4e5f6

B. git cherry-pick a1b2c3,d4e5f6

C. git cherry-pick -m a1b2c3 d4e5f6

D. git cherry-pick a1b2c3 d4e5f6

Solution

1. Step 1: Review cherry-pick syntax

   The correct way to cherry-pick multiple commits is to list their hashes separated by spaces, not commas or flags.

2. Step 2: Analyze options

   git cherry-pick a1b2c3 d4e5f6 uses spaces between commit hashes without extra flags, which is the correct syntax.

3. Final Answer:

   git cherry-pick a1b2c3 d4e5f6 -> Option D

4. Quick Check:

   Multiple commits separated by spaces [OK]

Hint: Separate commit hashes by spaces, not commas [OK]

Common Mistakes:

• Using commas between commit hashes
• Adding unnecessary flags
• Using incorrect options like --all

3. Given the following commands run on branch feature:

git checkout feature
git cherry-pick 123abc 456def

What will happen if both commits apply cleanly?

medium

A. Only the first commit 123abc will be applied, the second will be ignored.

B. The changes from commits 123abc and 456def will be added to the feature branch in order.

C. Git will merge the branches containing those commits into feature.

D. An error will occur because multiple commits cannot be cherry-picked at once.

Solution

1. Step 1: Understand cherry-pick with multiple commits

   When multiple commits are cherry-picked, git applies each commit sequentially if no conflicts occur.

2. Step 2: Effect on current branch

   Since the branch is feature, the changes from both commits will be added in the order listed.

3. Final Answer:

   The changes from commits 123abc and 456def will be added to the feature branch in order. -> Option B

4. Quick Check:

   Multiple commits apply sequentially [OK]

Hint: Cherry-pick applies commits one by one in order [OK]

Common Mistakes:

• Assuming only first commit applies
• Confusing cherry-pick with merge
• Thinking multiple commits cause errors

4. You run git cherry-pick abc123 def456 but get a conflict on the second commit. What should you do to continue cherry-picking the remaining commits?

medium

A. Fix the conflict, then run git cherry-pick --continue to proceed.

B. Abort the cherry-pick with git cherry-pick --abort and start over.

C. Run git reset --hard to discard changes and continue.

D. Use git cherry-pick --skip immediately without fixing conflicts.

Solution

1. Step 1: Handle conflicts during cherry-pick

   When a conflict occurs, you must manually fix it before continuing.

2. Step 2: Continue cherry-pick process

   After fixing conflicts, running git cherry-pick --continue resumes applying remaining commits.

3. Final Answer:

   Fix the conflict, then run git cherry-pick --continue to proceed. -> Option A

4. Quick Check:

   Fix conflicts + git cherry-pick --continue [OK]

Hint: Fix conflicts then run git cherry-pick --continue [OK]

Common Mistakes:

• Skipping conflicts without fixing
• Aborting instead of continuing
• Resetting hard loses work

5. You want to cherry-pick commits 111aaa, 222bbb, and 333ccc from branch dev onto main. However, 222bbb depends on changes in 111aaa, but 333ccc is unrelated. Which command correctly cherry-picks only the dependent commits in order?

hard

A. git checkout main && git cherry-pick 333ccc 111aaa 222bbb

B. git checkout main && git cherry-pick 222bbb 111aaa

C. git checkout main && git cherry-pick 111aaa 222bbb

D. git checkout main && git cherry-pick 111aaa,222bbb

Solution

1. Step 1: Identify dependent commits

   Since 222bbb depends on 111aaa, both must be cherry-picked in order to avoid errors.

2. Step 2: Choose correct command syntax and order

   git checkout main && git cherry-pick 111aaa 222bbb checks out main and cherry-picks commits in the correct order separated by spaces.

3. Final Answer:

   git checkout main && git cherry-pick 111aaa 222bbb -> Option C

4. Quick Check:

   Dependent commits cherry-picked in order [OK]

Hint: Cherry-pick dependent commits in order, skip unrelated [OK]

Common Mistakes:

• Cherry-picking commits in wrong order
• Including unrelated commits unnecessarily
• Using commas instead of spaces