每天一道LeetCode-----以单词为单位逆序字符串，每个单词之间以一个空格分隔(原字符串中可能有多个空格)

Reverse Words in a String

class Solution {
public:
void reverseWords(string &s) {
std::reverse(s.begin(), s.end());
int front = 0;
int prev = 0;
for(int i = 0; i <= s.size(); ++i)
{
if(i < s.size() && s[i] != ' ')
{
s[prev++] = s[i];
}
else
{
if(i > 0 && s[i - 1] != ' ')
{
/* 逆序单词的时候带着空格逆序 */
if(front != 0)
s[prev++] = ' ';
std::reverse(s.begin() + front, s.begin() + prev);
front = prev;
prev = prev;
}
}
}
s = s.substr(0, prev);
}
};