字符串的排列

class Solution {
public:
    vector<string> res;
    void pmu(string str,int begin,int len)
        {
        if(begin==str.size()-1)
            {
            res.push_back(str);
            return;
        }
        sort(str.begin()+begin,str.end());
        for(int i=begin;i<len;i++)
            {
            if(begin!=i&&str[begin]==str[i])
                continue;
            char tmp=str[begin];
            str[begin]=str[i];
            str[i]=tmp;
            pmu(str,begin+1,len);
            tmp=str[i];
            str[i]=str[begin];
            str[begin]=tmp;
        }
    }
    vector<string> Permutation(string str) {
        if(str.empty())
            return res;
        pmu(str,0,str.size());
        return res;
        //str.push_back(str);
    }
};