LeetCode | Reverse Words in a String（字符串中的单词序反转）

Given an input string, reverse the string word by word.

For example,

Given s = "

the sky is blue

",

return "

blue is sky the

".

click to show clarification.

Clarification:

What constitutes a word?

A sequence of non-space characters constitutes a word.
Could the input string contain leading or trailing spaces?

Yes. However, your reversed string should not contain leading or trailing spaces.
How about multiple spaces between two words?

Reduce them to a single space in the reversed string.

题目解析：

题目中要删除多余的空格，有一种比较简单的方法，先将s字符串赋给一个临时字符串tmp，将头尾空格略去，两个字间的空格只复制一次。然后对tmp进行常规操作。这样需要两遍遍历。

也可以临时设一个结果字符串，和一个临时的字串。一点一点处理

class Solution {
public:
void reverseWords(string &s) {
string tmp;
for(int i = s.size()-1;i >= 0;i--){
while(i >= 0 && s[i] == ' ')
i--;
if(i<0)
break;
if(!tmp.empty())
tmp.push_back(' ');
string word;
while(i>=0 && s[i]!=' ')
word.push_back(s[i--]);
reverse(word.begin(),word.end());
tmp.append(word);
}
s = tmp;
}
};