Using MAP STL:

int n,q;
cin >> n >> q;
cin.ignore();

map <string,string> attributeDB; // to store attribute-value pairs
string inputstr,tag_preamble="";

// get each HRML line
for (int i=0;i<n;i++) {
    getline(cin,inputstr);    

    // for each HRML line, break it up into token words
    stringstream ss(inputstr);
    string word, attribute, value;
    size_t pos;
    while (getline(ss, word, ' ')) { // for each token word
        // tag detected -> adjust tag_preamble by +/- tag
        if (word[0]=='<') {
            string tag;
            if (word[1]=='/') { // it's tag closing
                tag=word.substr(2);   
                tag=tag.substr(0,tag.length()-1); // rid of ">"
                pos=tag_preamble.find("."+tag);
                if (pos==string::npos) tag_preamble="";
                else tag_preamble=tag_preamble.substr(0,pos);
            }
            else { // it's tag opening
                tag=word.substr(1);
                if (tag.find(">")!=string::npos) 
                tag=tag.substr(0,tag.length()-1); // rid of ">"
                if (tag_preamble=="") tag_preamble=tag;
                else tag_preamble=tag_preamble+"."+tag;
            }
        }
        // value detected
        else if (word[0]=='"') {
            pos=word.find_last_of('"');
            value=word.substr(1,pos-1);
            attributeDB[attribute]=value; // insert into DB
        }
        // attribute name detected
        else if (word[0]!='=') {
            attribute=tag_preamble + "~" + word;  
        }
    }
}

// now we process the queries
for (int i=0;i<q;i++) {
    getline(cin,inputstr); 
    if (attributeDB.find(inputstr)==attributeDB.end())
        cout << "Not Found!" << endl;
    else
        cout << attributeDB[inputstr] << endl;
}