Programming Interview Questions

You have a stream of numbers that you can see one at a time. With uniform probability, select only one of these numbers. That is, each number in the stream has the same probability of being selected. You cannot just store the entire stream to an array or read through the stream twice.

>>10
Learn to probability my friend.

The probability of the value at iteration i being selected is also dependent on the fact that a value at iteration j where j > i, doesn't overwrite. They aren't independent events.