Microsoft Sr. Software Engineer interview questions

Algorithms, Datastructure, Design

You are given a 2D image with black and white pixels (0 and 1) and a position x,y. Find the connected component (1 pixels) containing x,y. I was also asked a couple followup questions about the disadvantages of recursion (too much memory overhead for the function calls), and how to implement my algorithm iteratively (answer: just use a stack! ...).