python如何将重复的字符串值重新分配给新字符串

Question

• 我接受了一个字符串aabullc

• newstring应该在循环后赋值aall，因为a和l是重复的

• 字符串有一个以上的副本，如aaabullc应该返回aaall

  def rearrangeLetters(S):
  print(len(S))
  start = 0
  newstring = ""
  for i in range(start+1, len(S)):
  if(S[start] == S[i]):
  newstring+=S[i]
  print(newstring)
  start +=1
  

问题:

print(newstring)从未运行

Answer 1

这样做可能会对您有所帮助:

你可以很容易地把它转换成你的函数。

s = 'aabullc'
from itertools import groupby
result = ''
for k, g in groupby(s):
#print(k, ''.join(g))
ss = ''.join(g)
if len(ss) >=2:
result += ss    # aall 

Answer 2

对于较短的字符串，只需收集已看到的内容列表就可以轻松地完成此操作，对于较长的字符串，如果添加set

，可能更有效。

def rearrange_letters(source_string):
result     = []     # collection to return
duplicated = set()  # efficient lookup for very long strings
for index, char in enumerate(source_string):
if char in duplicated:
result.append(char)
elif source_string[index:].count(char) > 1:
duplicated.add(char)
result.append(char)
return "".join(result)  # NOTE join is a method of string ""

>>> rearrange_letters("aabullc")
'aall'
>>> rearrange_letters("aaabcdc")
'aaacc'

Answer 3

试试这个:

def rearrangeLetters(S):
s = [S[i] for i in range(len(S))]
newstring = ""
for t in s:
if s.count(t) > 1:

newstring += t
return newstring

调用函数:

output = rearrangeLetters("aabullc")
print(output)

输出:

aall