翻转单词顺序列

https://www.nowcoder.com/practice/3194a4f4cf814f63919d0790578d51f3?tpId=13&tqId=11197&tPage=3&rp=1&ru=%2Fta%2Fcoding-interviews&qru=%2Fta%2Fcoding-interviews%2Fquestion-ranking

思路：

先对整体的句子进行翻转，然后对句子的每个单子进行翻转

class Solution {
public:

	string ReverseSentence(string str)
	{
        int length = str.length();
		if(length == 0)
			return "";
		reverse(str, 0, length - 1);//整体句子翻转
		
		int i = 0;
		int s,e;//分别指向翻转部分的起点和终点
		while(i < length)
		{
			while(i < length && str[i] == ' ')//过滤掉空格
				i++;
			s  = i;//空格后的第一个字符
		
			while(i < length && str[i] != ' ')//找到字符的结尾
				i++;
			e = i - 1;
			reverse(str, s, e);//局部翻转
		}
		return str;
			

	}

	//翻转s的startt~end的字符
	void reverse(string & s, int start, int end)
	{	
		string temp = s;
		int p = start;
		for(int i = end; i >= start; i--)
		{
			temp[p] = s[i];
			p++;
		}
		s = temp;

	}
};