对于ios7扫描二维码功能的实现

浏览数：18 / 时间：2015年06月11日

题目如下：

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.

题目要求不仅需要把字符串中的单词进行旋转，而且测试用例中还包含头尾含有空格、单词间空格数大于1个之类的字符串。所以要处理好空格，处理完空格的字符串肯定是小于或等于原字符串长度的，考虑到通过移动字符的方式来减小空格耗时长，我的思路是首先计算出去多余的空格后字符串应有的长度，然后重新定义一个临时字符串，开辟最终应有长度的空间。然后将原字符串逆序copy到新定义的字符串变量中，保证头尾多余空格已去除，保证单词间仅保留一个空格。然后将每个单词再进行一次反转，便实现了题目所要求的功能。AC代码如下：

class Solution {
public:
    void reverseWords(string &s) 
	{
		if(s.empty())
			return;
		int count = 0;
		int index = 0, indexTemp = 0, begin = 0, end = s.length()-1;
		while(s[begin] == ' ' && begin<s.length()-1)
			begin++;
		while(s[end] == ' ' && end>0)
			end--;
		if(end == 0 && s[end] == ' ')
		{
			s = "";
			return;
		}
		else if(end == 0)
		{
			s = s.substr(0,1);
			return;
		}
		index = begin;
		while(index <= end)
		{
			if(s[index] == ' ')
			{
				count++;
				while(s[index] == ' ')
					index++;
			}
			count++;
			index++;
		}
		string temp(count,'\0');
		index = end;
		indexTemp = 0;
		while(index >= begin)
		{
			if(s[index] == ' ')
			{
				temp[indexTemp] = s[index];
				while(s[index] == ' ')
					index--;
				indexTemp++;
			}
			temp[indexTemp] = s[index];
			indexTemp++;
			index--;
		}
		indexTemp = 0;
		begin = -1;
		end = -1;
		while(indexTemp < count)
		{
			if(temp[indexTemp] != ' ' && begin == -1)
			{
				begin = 0;
			}
			else if(indexTemp-1 >= 0 && temp[indexTemp-1] == ' '&&temp[indexTemp] != ' ')
			{
				begin = indexTemp;
			}
			else if((indexTemp+1 < count && temp[indexTemp+1] == ' ' && temp[indexTemp] != ' ') || ((indexTemp == count-1)&&temp[indexTemp] != ' '))
			{
				end = indexTemp;
				reverse(temp, begin, end);

			}
			indexTemp++;
		}
		s = temp;
    }
	
	void reverse(string &s, int begin, int end)
	{
		while(begin < end)
		{
			char temp = s[begin];
			s[begin] = s[end];
			s[end] = temp;
			begin++;
			end--;
		}
	}
};

对于ios7扫描二维码功能的实现,,5-wow.com

郑重声明：本站内容如果来自互联网及其他传播媒体，其版权均属原媒体及文章作者所有。转载目的在于传递更多信息及用于网络分享，并不代表本站赞同其观点和对其真实性负责，也不构成任何其他建议。

对于ios7扫描二维码功能的实现