How to check if characters in a string are alphabetically ordered

Question

I have been trying these code but there is something wrong. I simply want to know if the first string is alphabetical.

def alp(s1):
    s2=sorted(s1)
    if s2 i         


        

Answer 1

I would do it using iter to nicely get the previous element:

def is_ordered(ss):
   ss_iterable = iter(ss)
   try:
       current_item = next(ss_iterable)
   except StopIteration:
       #replace next line to handle the empty string case as desired.
       #This is how *I* would do it, but others would prefer `return True`
       #as indicated in the comments :)
       #I suppose the question is "Is an empty sequence ordered or not?"
       raise ValueError("Undefined result.  Cannot accept empty iterable")

   for next_item in ss_iterable:
       if next_item < current_item:
           return False
       current_item = next_item
   return True

This answer has complexity O(n) in the absolute worst case as opposed to the answers which rely on sort which is O(nlogn).