struct topic_info_t {    int topic_id;    float topic_pr;};float sim(const vector<topic_info_t>& query_info,const vector<topic_info_t>& adwords){    vector<topic_info_t>::iterator it1 = query_info.begin();    vector<topic_info_t>::iterator it2 = adwords.begin();    float sim = 0.0;    for (; it1 != query_info.end() && it2 != adwords.end() ;){        if(it1->topic_id == it2->topic_id){            sim += it1->topic_pr*it2->topic_pr;            it1++;            it2++;        }        else if(it1->topic_id < it2->topic_id)            it1++;        else            it2++;        }    return sim;}float max_sim(const vector<topic_info_t>& query_info,                const vector<topic_info_t> adwords_topic_info[],int adwords_number){    if (NULL == adwords_topic_info || adwords_number <= 0)        return 0.0;    float maxSim = sim(query_info,adwords_topic_info[0]);    int i = 1;    while(i<adwords_number){        simI = sim(query_info,adwords_topic_info[i]);        if(simI > maxSim)            maxSim = simI;    }    return maxSim;}