剑指offer-左旋转字符串

37.左旋转字符串

题目内容：

代码及思路：

以图示的栗子为例

#include
#include
using namespace std;
class Solution
{
public:
	string LeftRotateString(string str, int n)
	{
		if (str.length() <= 0)
			return "";
		int length = str.length();
		int firstindex = 0;
		int endfirst = n - 1;
		int secondindex = n;
		int endsecond = length - 1;
		if (n >= 0 && n < length)
		{
				Reverse(str, firstindex, endfirst); //先对第一部分进行求反序列
				Reverse(str, secondindex, endsecond);//先对第二部分进行求反序列
				Reverse(str, 0, length - 1);//对整个序列求反
		}
		return str;
	}
	void Reverse(string& str, int begin, int end)
	{
		if (begin > end)
			return;
		while (begin < end)
		{
			char temp = str[begin];
			str[begin] = str[end];
			str[end] = temp;
			begin++;
			end--;
		}
	}
};
void main()
{
	Solution* object = new Solution;
	string str;
	getline(cin, str);
	int n;
	cin >> n;
	str = object->LeftRotateString(str, n);
	cout << str << endl;
}