LeetCode 557. Reverse Words in a String III

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.

题目大意：将一个字符串的每个单词反转～
分析：将每个单词放入栈中，当遇到空格或者最后一个字符的时候，说明当前栈内为一个完整的单词，那么就将栈内的单词按字符一个个出栈加入result字符串中，根据flag的值判断是否是第一个单词，如果不是第一个单词就要在result的后面加一个空格～

class Solution {public:    string reverseWords(string s) {        string result = "";        stack<char> word;        int flag = 0;        for (int i = 0; i < s.length(); i++) {            if (s[i] != ' ')                 word.push(s[i]);            if (s[i] == ' ' || i == s.length() - 1) {                if (flag == 1) result += " ";                while (!word.empty()) {                    result += word.top();                    word.pop();                    flag = 1;                }            }        }        return result;    }};