LintCode 927: Reverse Words in a String

最新推荐文章于 2021-10-12 12:38:38 发布

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本文深入探讨了如何使用C++实现字符串的单词反转，重点讲解了string.find()方法的应用，通过实例展示了如何在不分配额外空间的情况下，按单词逆序排列字符串。

题目如下：
927. Reverse Words in a String II
Given an input character array, reverse the array word by word. A word is defined as a sequence of non-space characters.

The input character array does not contain leading or trailing spaces and the words are always separated by a single space.

Example
Given s = “the sky is blue”,
after reversing : “blue is sky the”

Challenge
Could you do it in-place without allocating extra space?

这题主要考string.find()的用法。
注意string.find(’ ', endPos+1)里面的endPos+1可以表示从什么地方开始找。

class Solution {
public:
    /**
     * @param str: a string
     * @return: return a string
     */
    string reverseWords(string &str) {
        string result;
        int startPos = -1, endPos = 0;
        size_t len = str.size();
        
        while (endPos < len) {
  
            endPos = str.find(' ', endPos + 1);
            if (startPos >= 0)
                result = str.substr(startPos + 1, endPos - startPos - 1) + ' ' + result;
            else 
                result = str.substr(startPos + 1, endPos);

            startPos = endPos;
        }
        return result;
    }
};