翻转单词顺序

class Solution {
public:
    string reverseWords(string s) {
        if(s.size()==0) return "";
        reverse(s.begin(),s.end());
        for (int i = 0; i < s.size();)
        {
            int j=i;
            while(j<s.size()&&s[j]!=' ')    j++;
            reverse(s.begin()+i,s.begin()+j);
            i=j+1;
        }
        return s;
    }
};