题目描述:牛客最近来了一个新员工Fish,每天早晨总是会拿着一本英文杂志,写些句子在本子上。同事Cat对Fish写的内容颇感兴趣,有一天他向Fish借来翻看,但却读不懂它的意思。例如,“student. a am I”。后来才意识到,这家伙原来把句子单词的顺序翻转了,正确的句子应该是“I am a student.”。Cat对一一的翻转这些单词顺序可不在行,你能帮助他么?
Solutions
两次反转字符串,第一次反转整句,第二次反转每个单词。
# -*- coding:utf-8 -*-
class Solution:
def ReverseString(self, s):
if s is None:
return None
begin = 0
end = len(s) - 1
while begin < end:
s[begin], s[end] = s[end], s[begin]
begin += 1
end -= 1
return s
def ReverseSentence(self, s):
# write code here
if s is None:
return None
s = list(s)
s = self.ReverseString(s)
begin = end = 0
n = len(s)
while begin < n:
if s[begin] == ' ':
begin += 1
end += 1
elif end < n and s[end] == ' ':
s[begin:end] = self.ReverseString(s[begin:end])
begin = end
elif end < n:
end += 1
elif end == n:
s[begin:end] = self.ReverseString(s[begin:end])
break
return ''.join(s)