The interview was for a software engineer position. I received the interview call through the campus career fair. It was a 45-minute telephonic interview. The interviewer was very polite and helpful. Unfortunately, I messed up things towards the end.

It started with the interviewer introducing himself and asking me to introduce myself. Then, there were some behavioral questions, such as why I was interested in Facebook, which team I preferred, and whether I was interested in Front-end or Back-end. He also asked a couple of questions about my projects and resume.

The interview happened on a Thursday. At the end, the interviewer said, "Sorry! Time's up." I understood then that I would not clear it. The following Monday, I received an email from the recruiter stating they could not move forward.

You have a string that consists of all types of characters: alphanumeric, special, uppercase, and lowercase. The string should still tell me if it is a palindrome or not.

For example, "12@#.Race@#car." is a palindrome. (Omit the special characters and do not consider the string to be case-sensitive).

I wrote the code in O(n), but I was using an extra string to store only the letters. The interviewer asked me to do it in place (use only that string and check for palindrome).