Google Testing Engineer interview questions

i gave my resume to a google employee in our school job fair, 1 month later i've got an email from google and they said they want to set an appointment with me at specific time. I've requested to postpone my interview so that i could prepare myself and they accepted... so, in the day of interview i've received a phone call from google, he was really nice and friendly, my first question was " if i give you a large document including text and numbers, n i ask you to retrieve just phone numbers, how will you do that? with which library of tool?"...and my second question was about santa-secret game, "if you want to make a list of students in the class who everyone give exactly 1 gift and everyone can receive exactly one gift, how you would do that?"...i wasn't sure about the first question that moment and i have no idea why he asked me such a question, and the answer of second one was using hash table.