leetcode:反转字符串II

题目链接

string reverse(string s1)
{
	string s2;
	string::reverse_iterator rit = s1.rbegin();
	while (rit != s1.rend())
	{
		s2 += *rit;
		rit++;
	}
	return s2;
}
class Solution {
public:
    string reverseStr(string s, int k) {
        string s1;
        int i = 0;//标记字符串下标
        int j = 0;
        int length =s.length();

        
             for (i = 0; i < length; i+=2*k)
            {
	            if (i+2*k<length)
	            {
		            string tmp = s.substr(i, k);//字符串s从i号下标位置取k个字符
		            tmp = reverse(tmp);
		            s1 += tmp;
		            s1 += s.substr(i + k, k);
	            }
	            else if (i + 2 * k >= length&&i+k<length)
	            {
		            string tmp = s.substr(i, k);//字符串s从i号下标位置取k个字符
		            tmp = reverse(tmp);
		            s1 += tmp;
		            s1 += s.substr(i + k, length - (i + k));
	            }
	            else//i+k>length
	            {
		            string tmp = s.substr(i, length);//字符串s从i号下标位置取k个字符
		            tmp = reverse(tmp);
		            s1 += tmp;
	            }
            }
        
        return s1;
    }
};