Google's code comprehension round
A comprehension round starts from code somebody else wrote instead of a blank editor. In the practice version here the work is reading it accurately, finding what is wrong and making it faster, with an assistant available the whole time.
What is known about the real round
A code comprehension round with Gemini as the assistant is being piloted on some US teams. Other coding rounds stay AI-free.
Reports say the pilot covers junior and mid-level roles on selected US teams, and that candidates read an existing codebase, fix a bug and extend it with Gemini available. The standard algorithm rounds and the phone screen are reported as unchanged, with no AI allowed. Most of the detail comes from career-centre and prep-site write-ups, so ask your recruiter whether your loop includes the pilot.
Formats change between hiring cycles. Ask your recruiter what your round will be, and see the policy tracker for other companies.
How the practice round runs
Placed runs its own version of this format with a voice interviewer. The codebase and the tasks are Placed's, not Google's.
- Step 1Read before you touch
You get a codebase and a description of what it should do. Start by saying, out loud, what each part does and where the data flows. The assistant can summarise a file for you, and you still have to check the summary against the code.
- Step 2Fix what is wrong
There is a defect. Reproduce it first, then explain the cause in a sentence, then change the code. A fix you cannot explain does not count for much.
- Step 3Make it faster
The code is correct now and too slow for the stated budget. Find the expensive step, change it, and confirm the output did not change.
What gets scored
The report scores 4 things from 0 to 10: problem solving, code quality, verification, communication. On Pro, each score comes with the moment in your session it is based on. How grading works.
Where people lose the round
- Trusting the assistant's summary of a file you have not read.
Use the summary as a map, then open the function it describes and check one claim against the code.
- Fixing the symptom without reproducing the bug.
Write or run the smallest input that fails. Then you can show the fix worked.
- Optimising by guessing.
Say the complexity of the slow path before and after. That is what the interviewer writes down.
- Treating it like an algorithm round and rewriting everything.
Change as little as the task needs. Reading and keeping what works is the skill being tested.
Three sessions before the real one
- Sit one comprehension round and time how long you spend reading before your first edit.
- Do a code review round, which is the same reading skill with no editing.
- Sit the comprehension round again a few days later and compare the reports.
Placed is not affiliated with Google. Company names are used to describe publicly reported interview formats.