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LeetCode:Reverse Words in a String

时间:2014-07-22 23:13:32      阅读:309      评论:0      收藏:0      [点我收藏+]

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Reverse Words in a String

  

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

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

  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.
  • 题目大意:给定一个字符串,对字符串进行逆转。
  • 解题思路:看到这道题目有两种思路:

    1)用两个指针从前到后扫描,分开单词,先对每个单词进行逆转,最后再对整个字符串逆转;

    比如题目中给的例子:先对每个单词进行逆转得到的结果:"eht yks si eulb",然后再整体逆转即可得到"blue is sky the"。

    2)根据空格切分字符串,将切分得到的单词存到vector中,然后将vector中的单词从末尾开始输出即可。

    在衡量了两种方法之后,觉得第二种方法代码更加简洁方便,便选择了第二种思路。   

  • 实现:
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void reverseWords(string &s) {
        int i=0,j=0;
        int len = s.length();
        vector<string> splitResult;
             
        while(i<len)
        {
            if(s[i]==‘ ‘)
                i++;
            else
            {
                j=i+1;
                while(j<=len)
                {
                    if(s[j]==‘ ‘||j==len)
                    {
                        string tempStr = s.substr(i,j-i);
                        splitResult.push_back(tempStr);
                        i=j+1;
                        break;
                    }
                    else
                        j++;
                }
                        
            }  
        }
        int size = splitResult.size();
        if(size>0)
        {
            s="";
            for(i=size-1;i>0;i--)
                s+=splitResult[i]+" ";
            s+=splitResult[i];
        }
        else
        {
            s="";
        }
         
    }

  注意的地方:我一开始提交就提示错误,要考虑到空字符串以及只有空格组成的字符串,因此要在最后作一个判断,如果splitResult为空,则直接把s赋值为""即可。  

  

LeetCode:Reverse Words in a String,码迷,mamicode.com

LeetCode:Reverse Words in a String

标签:style   blog   http   color   os   strong   

原文地址:http://www.cnblogs.com/dolphin0520/p/3700019.html

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