LeetCode Reverse Words in a String(反转字符串)

class Solution {
public:
void reverseWords(string &s) {
if(s=="");
else
{
vector<string> vec;
int start = 0;
for(int i=0;i<s.length();i++)
{
if(s.at(i)==' ')
{
vec.push_back(s.substr(start,i-start));
start = i+1;
}
else if(i == s.length()-1)
{
vec.push_back(s.substr(start,i+1 - start));
}
}
std::reverse(vec.begin(),vec.end());
vector<string>::iterator iter = vec.begin();
s.erase();
while(iter != vec.end())
{
s+=*iter+" ";
iter++;
}
s.erase(s.length()-1);
}
cout<<s<<endl;

}
};