#Given a set of 2D points, some integer k, find the k points closest to the origin, (0,0).



#How will you describe iOS manual memory management for a new developer in few words?



#Write a program to print the powerset. 

E.g. given this set {1,2,3}, it will print {},{1},{2},{3},{1,2},{1,3}, {2,3}, {1,2,3}



#Convert a string of Roman numerals to an integer in O(n) time



#Given a list of integer numbers, a list of symbols [+,-,*,/] and a target number N, provide an expression which evaluates to N or return False if that is not possible. 

e.g. let the list of numbers be [1,5,5] and the target number is 9, one possible solution could be 5+5-1.



#Given an expression (in single variable) like 4x+13(x-(4x+x/3)) = 9, evaluate x 

The expression is a string and the variable is always x.



#Given a hashmap M which is a mapping of characters to arrays of substitute characters, and an input string S, return an array of all possible mutations of S (where any character in S can be substituted with one of its substitutes in M, if it exists). 

What is the time complexity? What is the space complexity? Can you optimize either?

Example input:

	M = { f: [F, 4], b: [B, 8] }

	S = fab



Expected output:

	[fab, Fab, 4ab, faB, FaB, 4aB, fa8, Fa8, 4a8]



##Brain storming:

1) How does facebook implement graph search 

2) How does facebook chat work 

3) How does fb store likes/dislikes ? 

4) How do u implement status updates ? 

5) How do u implement timeline/newsfeed ? 

6) What exactly happens when you add someone as your friend ? 

7) Explain more about hadoop and how it is used ? 

8) How do fb messages work ? 

9) How does fb mail work ? 

HAVE YOUR SAY...