leetcode_151.翻转字符串里的单词

给定一个字符串，逐个翻转字符串中的每个单词。

输入: "the sky is blue"
输出: "blue is sky the"

• 利用istringstream函数

  class Solution {
  public:
    string reverseWords(string s) {
        istringstream words(s);
        stack<string> st;
        string res;
        string word;
        while(words >> word) {
            st.push(word);
        } 
        while (!st.empty()) {
            string tmp = st.top(); st.pop();
            if (st.size() != 0)
                res += tmp + " ";
            else 
                res += tmp;
        }
        return res;
    }
  };