scheme和python中的递归

Posted 2021-02-25

# scheme:
 
(define (downup wd)
  (if (= (count wd) 1)
      (se wd)
      (se wd (downup (bl wd)) wd)))
 
> (downup 'toe)
(TOE TO T TO TOE)
 
> (downup 'banana)
(BANANA BANAN BANA BAN BA B BA BAN BANA BANAN BANANA)
 
 
# now in python
 
def downup(word):
    if len(word) == 1:
        return [word]
    return [word] + downup(word[1:]) + [word]
 
print downup("bananas")