A recruiter emailed me a long time ago, in 2009, but I was not available at that time. I started looking for different opportunities earlier this year and contacted their recruiter. The recruiter filtered my email, so I waited several months without a response. However, with help from my friend at Facebook, I finally was able to contact the recruiter in mid-March. I had two phone interviews with them. The first one went well, but the second one stumbled me. Then, I was rejected after 2-3 days.

Write a function to determine if two line segments intersect.