• The phone interview was like a joke. They asked my GPA?!? It's in my resume; I hoped the interviewer read my resume before making a call. Fortunately, I had it open.

• The skill assessment test was easy, just to make sure that your resume is really your resume.

• The onsite interview process was really organized and pretty rewarding.

• I was surprised that my interviewer knew what I was presenting about, given that my topic was highly specialized.

• Got tired after the whole day of onsite interview process.

I have a log that consists of more than 100 million lines.

Each line is just data about user login, login time, etc. I want to sort them based on user login, and then if there is a tie, based on login time, etc.

However, I have limited memory, so don't think of storing all of them in an array. The memory can only hold n data, where n is much smaller than 100 million.

You can access the disk, though it is much slower. How will you do it so that it is as efficient as possible?

Please write a function that accepts a floating-point number and returns its square root. You may not use the built-in square root function from your language. However, basic operators like addition, subtraction, and multiplication are allowed. Please take floating-point precision into consideration.