Reverse Words in a String

class Solution {
public:
    void reverseWords(string &s) {
        int n = s.length();
        if(n == 0) return;
        vector<string> pool;
        int i = 0;
        while(s[i] == ‘ ‘)i++;
        string tmp;
        for(int j = i; j < n; j++){
            if(s[j] != ‘ ‘){
                tmp.push_back(s[j]);
                if(j == n-1)
                    pool.push_back(tmp);
            }
            else{
                if(s[j-1] != ‘ ‘){
                    pool.push_back(tmp);
                    tmp.clear();
                }
            }
        }
        s.clear();
        for(auto a = pool.rbegin(); a != pool.rend(); a++){
            s.append(*a);
            s.push_back(‘ ‘);
        }
        if(s.length() != 0)
            s.pop_back();
    }
};