Given a tree of the organizational structure, let's say a company like "Google" .
Also mentioned that the root is always Engineer.

class Employee {
int employeeId;
boolean isEngineer;
List reportees;
}

Given a tree

							E1
			________________|________________
			|               |               | 
		   E2              NE1             E3
		___|___             |               
		|     |             |               
		E4    NE2           E5 

Convert this graph to Engineer only graph.

							E1
			________________|________________
			|               |               | 
		   E2              E5               E3
		   |                                                       
		   E4               

In the above figure, E represents Engineers and NE represents Non-Engineers.
He also asked me to modify code at the end, also gave me an option to use a new graph or to modify the current graph.
I used a new graph, he seemed convinced .