Algorithm

【leetcode】557. Reverse Words in a String III

https://leetcode.com/problems/reverse-words-in-a-string-iii/

1）problem

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.

2）answer

判断是否为空格，然后每个单词转换。有一个很好用的交换函数swap。

3）solution

class Solution {
public:
    string reverseWords(string s) {
        int begin = 0;
        int end = 0;
        for (int i = 0; i <= s.length(); ++i) {
            //如果遇到了空格，就准备颠倒每个字符串的值
            if (s[i] == ' ' || s[i] == '\0') {
                end = i;
                // 转换每个单词的值，end是单词的结尾长度，j是单词开始长度。
                for (int j = begin; j < end; ++j) {
                    std::swap(s[j], s[--end]);
                }
                begin = i + 1;
            }
        }
        return s;
    }
};