C3 Energy

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C3 Energy Interview Questions & Reviews

Updated Jul 7, 2014
All Interviews Received Offers

Getting an Interview  

43%
37%
18%

Interview Experience  

69%
23%
7%

Interview Difficulty  

Average Difficulty
15 candidate interviews
Relevance Date Difficulty
in

No Offer

Neutral Experience

Very Difficult Interview

Software Engineer Interview

Software Engineer

I applied online and the process took 3 days - interviewed at C3 Energy in June 2014.

Interview Details – the first step is the online test, and there are three problems, one is difficult, one is middle, and the last is easy, but time is limited and few people would pass that, I guess. And I failed to pass this online test.The platform uses 3 party website, and the oj system would not check whether your algorithm is good in time complexity.

Interview Question – one difficult graph questions, and two other easier problems, but time is limited   Answer Question


No Offer

Positive Experience

Very Difficult Interview

Software Engineer Interview

Software Engineer
Santa Clara, CA

I applied online and the process took a day - interviewed at C3 Energy in June 2014.

Interview Details – I applied online and it took one day! Then I took a online test. I was too naive to think the online test is a really easy one. It turned out that it was quite hard. They didn't provide me with the signature of the function and I need to figure it out by myself. What's more, it was a one-hour test, which I thought was quite a hurry.

Interview Question – change the pointer of the nodes so that all of them can be good nodes.   View Answer


Accepted Offer

Positive Experience

Average Interview

Executive Assistant Interview

Executive Assistant
Redwood City, CA

I applied through a recruiter and the process took 1 week - interviewed at C3 Energy in April 2014.

Interview Details – Everyone was friendly and transparent about the job expectations. I enjoyed meeting a wide range of employees during the process. Some of the interviews were conducted in open, common office areas within ear-shot of other employees - not for the shy! Onboarding went very quickly. You are expected to jump into the work and do more than 100%.


No Offer

Neutral Experience

Software Engineer Interview

Software Engineer

Interviewed at C3 Energy

Interview Details – Applied online, receive a coding challenge. 3 questions in one hour, a little hurry. Did not good, and receive rejection in the night. Good company if you want an interview quickly. And feels like they are really hiring talented people.

Interview Question – Graph problem which I have not well prepared.   Answer Question


No Offer

Neutral Experience

Software Engineer Interview

Software Engineer

I applied online and interviewed at C3 Energy.

Interview Details – Applied through career site and after few weeks got a reply from them for a coding exam. There are 3 questions: search element in tree, find a sum in array by adding two number in array. After that I was scheduled for skype interview. Skype was another technical interview. find different keys in a n*n array from each position and key should be of length 5.


No Offer

Positive Experience

Difficult Interview

Data Engineer Interview

Data Engineer
Redwood City, CA

I applied through a recruiter and the process took 3 weeks - interviewed at C3 Energy.

Interview Details – Overall, a good experience. Started with an interviewstreet.com programming test (rather hard for one hour if problems are unfamiliar), then interactive coding over Skype, then an on-site with four people who all asked different types of whiteboard puzzles. Final interview is with managers and eventually the CEO.

Interview Question – Be ready for mathematical formulation questions. Whiteboard coding is a must. The culture is more buttoned-down than the typical jeans-and-tshirt tech startup.   Answer Question


No Offer

Positive Experience

Difficult Interview

Software Engineer New Grad Interview

Software Engineer New Grad

I applied online and the process took 2 days - interviewed at C3 Energy in February 2014.

Interview Details – The first round was an online test ( a hour and a half )
There was an online compiler with test cases.
the second round was a phone interview where I was asked to solve a problem

Interview Question – Generate all possible lock combinations on an android lock screen of length 5 such that each numbers are adjacent to each other and no repetitions within a combination.   View Answer


3 people found this helpful

No Offer

Negative Experience

Average Interview

Data Engineer Interview

Data Engineer
Redwood City, CA

I applied through college or university and the process took 3 months - interviewed at C3 Energy in November 2013.

Interview Details – The hiring process at C3 is extremely disorganized and disrespectful. I had a phone screen with a software engineer after which I was told that they are interested in discussing further. After two weeks' of silence I wrote to the HR director and she told me that someone was supposed to send me a puzzle but it never happened. I then took a couple of days to solve the puzzle and sent it back immediately. It was another two weeks' silence after which I had a phone screen with a team. The phone screen was the best part of the process because the person I spoke with was very talented and seemed to care about me. I was then invited on site. I had to drive for more than an hour to get to their office. The hiring manager told me I had three confirmed interviews. However, after my first interview, they seemed to run out of interviewers because of meetings and I believe that the software engineer who came in next did not expect to interview me and she threw a random coding problem at me which had nothing to do with the role I was interviewing for. Neither mentioned the puzzle I solved, the first interviewer even asked me what interview processes I had went through. I was then told to leave and was expected to visit them again if they wanted to proceed further. I did not feel respected and cared about throughout the process and regret spending a whole weekend on their puzzle.


3 people found this helpful

No Offer

Neutral Experience

Data Scientist Interview

Data Scientist

Interviewed at C3 Energy

Interview Details – On-campus recruiting interview. Had to meet up with them in a room on campus. Mainly technical (about an hour in length), some basic questions involving system/model estimation and some machine learning techniques. I was mainly writing on the white board and at one point ended up deriving the general form for solving a linear least squares problem. Interviewer seemed interested in seeing how deep my knowledge of the material went.

Interview Question – What is PCA/Singular Value Decomposition and can you derive why it works?   Answer Question


No Offer

Positive Experience

Very Difficult Interview

Software Engineer Interview

Software Engineer
Redwood City, CA

I applied through a recruiter and the process took 1 week - interviewed at C3 Energy in May 2013.

Interview Details – The team was very responsive in the process and I started out doing a phone interview and this led to an onsite interview. A very smart engineering and management team who put me through some difficult design and coding questions.

Interview Question – Find max k elements among mostly sorted list.   Answer Question

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