1. Calculate the square root of a double.

2. Given n intervals [si, fi], find the maximum number of overlapping intervals.

3. Print all the paths from the root to every leaf in a binary tree.

4. Print the sum of all numbers at every vertical level in a binary tree.

5. Given a set of n jobs with [start time, end time, cost], find a subset so that no two jobs overlap and the cost is maximum.

6. Given 1 trillion messages on Facebook, and each message has at most 10 words, how do you build the index table and how many machines do you need on the cluster to store the index table?

Given a set of n jobs with [start time, end time, cost], find a subset so that no two jobs overlap and the cost is maximum.