Facebook came to my university for their "Face Off" recruitment event. I applied to Facebook via their website and secured a guaranteed phone interview by participating in their whiteboarding competition. The interview was scheduled for two weeks later.

Disclaimer: This would be my first ever phone coding interview.

I was called promptly at our starting time, already prepared with the coding website open. Facebook disabled the website's compile functionality, leaving it as a syntax-highlighted text editor. After five minutes of the employee describing her role at Facebook, she proceeded to explain the technical question. This caught me off guard as there was no behavioral question, contrary to what the website and recruiters had suggested. After five minutes of explaining the problem and running through test cases, the interviewer stopped and allowed me to ask any questions I had. The interviewer's voice was a little difficult to understand when mentioning specific details, but the general idea was communicated for the duration of the call. I only had to ask for repetition twice. I then proceeded to explain the steps I would take to solve the problem over the phone, outlining my approach, a possible working solution, and the necessary runtime and space-time requirements. I was cut off during the Big O discussion and asked to ignore that for the time being, and instead begin coding. This was probably about 15 minutes into the interview at this point. During the coding process, I frequently asked if certain assumptions could be made about the code. More often than not, I received an inclusive "or" response ("Yes") when the question wasn't phrased for a simple yes or no, leading to multiple awkward pauses. I finished coding my first initial draft of the solution around the 40-minute mark. I asked if it was alright to start testing by walking through the code. We did this until the 51-minute mark, where she cut me off to inform me we were running out of time. She pointed out an error in my code before moving on to say I could ask her one question about Facebook with the time we had left.

Overall, the interview seemed more focused on solving the problem than the details surrounding it. I have no idea if my explanation before coding was of any value.

Given a 2D array of letters, return whether a given word can be found in the grid.

To make a word, you can use any adjacent character next to the character you're currently on in the word. However, you cannot use the same grid index twice.

For example, in a 2x2 array, you could find a 4-letter word by visiting each letter once.