290. Word Pattern

class WordPattern {
public:
    bool wordPattern(string pattern, string str) {
        if (pattern.empty() && str.empty())
        {
            return true;
        }
        if (pattern.empty() || str.empty())
        {
            return false;
        }
        map<char
 
, string> mc2str;
        map<string, char> mstr2c;
        vector<string> vstr = split(str, " ");
        if (pattern.size() != vstr.size())
        {
            return false;
        }
        for (int i = 0; i < pattern.size(); i++)
        {
            if ((mc2str.find(pattern[i]) != mc2str.end() && mstr2c.find(vstr[i]) == mstr2c.end()) ||
                (mc2str.find(pattern[i]) == mc2str.end() && mstr2c.find(vstr[i]) != mstr2c.end()))
            {
                return
 
 false;
            }
            if (mc2str.find(pattern[i]) == mc2str.end())
            {
                mc2str[pattern[i]] = vstr[i];
                mstr2c[vstr[i]] = pattern[i];
            }
            else
            {
                if (mc2str[pattern[i]] != vstr[i])
                {
                    return
 
 false;
                }
            }
        }
        return true;
    }

    vector<string> split(string str,string pattern)
    {
        string::size_type pos;
        vector<string> result;
        str += pattern;//擴充套件字串以方便操作
        int size = str.size();

        for(int i = 0; i < size; i++)
        {
            pos = str.find(pattern, i);
            if(pos < size)
            {
                std::string s = str.substr(i, pos-i);
                result.push_back(s);
                i = pos + pattern.size() - 1;
            }
        }
        return result;
    }
};