擅长:python、mysql、java
<pre><code># s is a 7 character string
s = "wxyabcd"
# set `mystring` to be the first character of s, 'w'
myString = s[0]
# set `longest` to be the first character of s, 'w'
longest = s[0]
# loop from 1 up to and not including length of s (7)
# Which equals for i in (1,2,3,4,5,6):
for i in range(1, len(s)):
# Compare the character at i with the last character of `mystring`
if s[i] >= myString[-1]:
# If it is greater (in alphabetical sense)
# append the character at i to `mystring`
myString += s[i]
# If this makes `mystring` longer than the previous `longest`,
# set `mystring` to be the new `longest`
if len(myString) > len(longest):
longest = myString
# Otherwise set `mystring` to be a single character string
# and start checking from index i
else:
myString = s[i]
# `longest` will be the longest `mystring` that was formed,
# using only characters in descending alphabetic order
print longest
</code></pre>