字符串中旋轉單詞

/*
問題描述：給定一個字符串，單詞以空格隔開，對字符串進行轉換，例如“I love you”轉換成“you love I”，要求空間複雜度爲O(1)
來源：網易算法課
日期：2017-10-24
說明：共分爲兩步，第一步：將整個字符串進行翻轉；第二步：對每個單詞進行翻轉
*/

#include <iostream>
#include <string>
using namespace std;

void reverseString(string& str, int begin, int end)
{
	int i = begin, j = end;
	while (i < j)
	{
		char c = str[i];
		str[i] = str[j];
		str[j] = c;
		i++;
		j--;
	}
	//cout << str << endl;
}

void reverseWord(string& str)
{
	reverseString(str, 0, str.length() - 1);
	cout << str << endl;
	int begin = 0, end = begin;

	while (end < str.length())
	{
		while (str[end] != ' ' && end < str.length())
			end++;
		reverseString(str, begin, end - 1);
		begin = end + 1;
		end = begin;

	}

}
/*
int main()
{
	string str = "im love you";
	//reverseString(str, 0, str.length() - 1);
	reverseWord(str);

	cout << str << endl;
	return 0;
}
*/