I changed the description and added some test cases.

Please go through nd i hope you'll be satisfied.

Thnkx for your suggestion and response. I truely appreciate it.

I changed the description, trying to solve all the confusions and discrepancy and have wrote all this with some eye candy and have added some test cases also.
I hope this will help while solving for others.
Please see for any mistake (human here ;) ).

And thnkx a ton for such a gud response and suggestion.

i corrected that nil test case with zero, will add some more test cases soon. I didn't get what you said in last of your solution. I would appriciate a more descriptive form of it. Thnkx

i really dont know how to help with that. Any suggestions??

its done, thnkx for the suggestion though. Appreciate it.