LeetCode Reverse Words in a String(反转字符串)_leetcode reversewords c++-优快云博客

本文详细介绍了如何使用C++编程语言实现输入字符串中单词的逆序操作，包括去除首尾空格、处理连续空格以及最终输出逆序后的字符串。

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题目要求：

Given an input string, reverse the string word by word.

For example,
Given s = "the sky is blue",
return "blue is sky the".

click to show clarification.

Clarification:

What constitutes a word?
A sequence of non-space characters constitutes a word.
Could the input string contain leading or trailing spaces?
Yes. However, your reversed string should not contain leading or trailing spaces.
How about multiple spaces between two words?
Reduce them to a single space in the reversed string

我是用c++ 写的：

class Solution {
public:
  void reverseWords(string &s) {
    size_t idx_start = 0;
    size_t idx_end;
    //erase the space at head and trail
    idx_start = s.find_first_not_of(" ");
    s.erase(0, idx_start);
    idx_end = s.find_last_not_of(" ");
    s.erase(idx_end + 1);
    reverse(s.begin(), s.end());
    idx_start = 0;
    string ret;
    string tmp;
    while(true)
    {
      tmp.clear();
      idx_end = s.find(' ', idx_start);
      if(idx_end == string::npos)
        break;
      //deal the sitution of contiguous spaces like "   "
      if(s[idx_start] == ' ')
      {
        idx_start = idx_end + 1;
        continue;
      }
      tmp = s.substr(idx_start, idx_end - idx_start);
      reverse(tmp.begin(), tmp.end());
      ret.append(tmp);
      ret.append(" ");
      idx_start = idx_end + 1;
    }
    //reverse the last word
    tmp = s.substr(idx_start);
    reverse(tmp.begin(), tmp.end());
    ret.append(tmp);
    s = ret;
  }
};