answer:
1.2. Through this question, I learned about istringstream. The istringstream object can bind a line of string, and then separate the line with a space as a separator.
(1) istringstream word (s) first construct a string input stream
(2) while (word >> w) reads a string from the input stream
class Solution {
public:
string reverseWords(string s) {
istringstream word(s);
string w;
string res;
while(word>>w) res=' '+w+res;
return res.empty()?"":string(res.begin()+1,res.end());
}
};
2. It is also using istringstream, you can save each string in the vector, and finally connect
class Solution {
public:
string reverseWords(string s) {
istringstream word(s);
vector<string> vec;
string w;
string res;
while(word>>w) vec.push_back(w);
for(int i=vec.size()-1;i>=0;i--) res+=vec[i]+' ';
return res.empty()?"":string(res.begin(),res.end()-1);
}
};
