After writing algorithm Expectation was told to me that use some .Net Enumerator functions. I thought it was test of logic and approach :-) Okay then I thought we could use Push/Pop or Insert/Remove in someway. And that’s all, you can leave now. Seriously, No WPF, no MVVM, No explain your Project, No DB, No Data Structure, no WCF, no Security?? I could sense the work they would have by interview, anyways life is like that.