557. Reverse Words in a String III

题目描述：

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: "Let's take LeetCode contest"
Output: "s'teL ekat edoCteeL tsetnoc"

 

Note: In the string, each word is separated by single space and there will not be any extra space in the string.

解题思路：

不难，根据空格找到每个单词，使用reverse方法进行翻转。在输入字符串本地操作，速度会快些。

代码：

class Solution {
public:
    string reverseWords(string s) {
        string res;
        size_t index;
        while ((index = s.find(" ")) != string::npos) {
            string word = s.substr(0, index);
            reverse(word.begin(), word.end());
            res += word + " ";
            s = s.substr(index+1);
        }
        reverse(s.begin(), s.end());
        res += s;
        return res;
    }
};