class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        if(strs.size() == 0)
            return "";
        string str;
        int lengthmin = strs[0].length();
        for(int i = 0; i < strs.size(); ++i)
        {
            if(lengthmin > strs[i].length())
                lengthmin = strs[i].length();
        }
        for
 
(int i = 0; i < lengthmin; ++i)
        {
            std::vector<string>::iterator iter;
            for(iter = strs.begin()+1; iter != strs.end(); ++iter)
            {
                if((*iter)[i] != (*(iter-1))[i])
                    return str;
            }
            str += strs[0][i];
        }
        return
 
 str;
    }
};