Google Software Engineer - Internship interview questions

There were screening round, and multiple behavioral and technical interview rounds. Applied. through Google Carriers and got the email with screening test URL. The screening round was composed with two programming questions.

First I got an Online Assessment which was pretty simple. Then I was invited for an interview having 2 rounds. Each interview was 45 minutes long. Both the rounds had only coding questions. The code had to be written in a Google doc while explaining the approach to the interviewer. The interviewers give you hints if you are stuck. Both of the questions were difficult. One was a string problem and the other involved backtracking.