I was emailed about an opportunity to work at Google.

The email asked me to set up a phone interview, where they asked about my interests and background.

They then set up another phone interview, this time a technical one.

The technical interview involved coding and asking the interviewer questions about his role at Google.

After the first interview, I received another phone call from my recruiter.

My recruiter said I needed one more technical phone interview before an on-site interview, so we scheduled one.

The second interview was similar to the first.

Write code to determine if a given input string contains balanced parentheses.