leetcode-----811-子域名访问计数

Map手到擒来，先找访问次数，然后把访问域名拆解成各级域名，再加上访问次数。

class Solution {
public:
    vector<string> subdomainVisits(vector<string>& cpdomains) {
        map<string,int> m;
        for(int i=0;i<cpdomains.size();i++)
        {
            int index_=cpdomains[i].find(' ');
            int count=stoi(cpdomains[i].substr(0,index_));
            string key = cpdomains[i].substr(index_+1);
            m[key]+=count;
            while( (index_=key.find('.'))!=string::npos)
            {
                key=key.substr(index_+1);
                m[key]+=count;
            }
        }
        
        vector<string> r;
        for(auto &i:m)
        {
            r.push_back(to_string(i.second) + " " + i.first);
        }
        return r;
    }
};