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From: John Gordon <gordon@panix.com>
Newsgroups: comp.lang.python
Subject: Re: Python solve problem with string operation
Date: Thu, 16 Jan 2014 22:58:44 +0000 (UTC)
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In <mailman.5609.1389912537.18130.python-list@python.org> Mark Lawrence <breamoreboy@yahoo.co.uk> writes:

> > input = "344111133311222223377"
> > output = []
> > previous_ch = None
> > for ch in input:
> >      if ch != previous_ch:
> >          output.append(ch)
> >          previous_ch = ch
> > print ''.join(output)
> >

> Cheat, you've used a list :)

Ack!  I missed that the OP doesn't want to use lists.

Well, let's try this instead:

    import sys

    input = "344111133311222223377"
    previous_ch = None
    for ch in input:
         if ch != previous_ch:
             sys.stdout.write(ch)
             previous_ch = ch
    sys.stdout.write('\n')

-- 
John Gordon         Imagine what it must be like for a real medical doctor to
gordon@panix.com    watch 'House', or a real serial killer to watch 'Dexter'.