剑指offer-翻转单词顺序列

class Solution {
public:
    string ReverseSentence(string str) {
        reverse(str.begin(), str.end()); 
        
        int start = 0; 
        for(int i=0; i<str.length(); ++i){
            if(str[i] == ‘ ‘){
                reverse(str.begin() + start, str.begin() + i); 
                start = i + 1; 
            }else if(i == str.length() - 1){
                reverse(str.begin() + start, str.end()); 
            }
        }
        return str; 
    }
};