spacegame spacegame - 2 months ago 42
Python Question

Find the longest substring in alphabetical order

I have this code that I found on another topic, but it sorts the substring by contiguous characters and not by alphabetical order. How do I correct it for alphabetical order? It prints out

lk
, and I want to print
ccl
. Thanks

ps: I'm a beginner in python

s = 'cyqfjhcclkbxpbojgkar'
from itertools import count

def long_alphabet(input_string):
maxsubstr = input_string[0:0] # empty slice (to accept subclasses of str)
for start in range(len(input_string)): # O(n)
for end in count(start + len(maxsubstr) + 1): # O(m)
substr = input_string[start:end] # O(m)
if len(set(substr)) != (end - start): # found duplicates or EOS
break
if (ord(max(sorted(substr))) - ord(min(sorted(substr))) + 1) == len(substr):
maxsubstr = substr
return maxsubstr

bla = (long_alphabet(s))
print "Longest substring in alphabetical order is: %s" %bla

Answer

Try changing this:

        if len(set(substr)) != (end - start): # found duplicates or EOS
            break
        if (ord(max(sorted(substr))) - ord(min(sorted(substr))) + 1) == len(substr):

to this:

        if len(substr) != (end - start): # found duplicates or EOS
            break
        if sorted(substr) == list(substr):

That will display ccl for your example input string. The code is simpler because you're trying to solve a simpler problem :-)

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