try this test case

dfadfmmmmfad

Correct answer

dfadad

Hope this helps...

thank you very much!

Hi,
    I am getting "fd" as answer as shown below after each removal of duplicate characters.

dfadfmmmmfad
dfadad
dfdd
fd
Could you please explain where am I wrong??

Thanks in advance.
Anupam

Why are you removing "a" chars in "dfadad"? You can delete it if chars stays together in the string.