rotate string

code

class Solution {
public:
    /**
     * @param str: a string
     * @param offset: an integer
     * @return: nothing
     */
    void rotateString(string &str,int offset){
        //wirte your code here
        if(str.empty())
        {
            return ;
        }
        int n = (int)str.length();
        offset = offset%n;
        string shadow;
        for(int i = 0; i<n; i++)
        {
            int j = (n-offset+i)%n;
            shadow.push_back(str[j]);
        }
        str = shadow;
    }
};