map

#include<iostream>
#include<string>
#include<cstring>
#include<map>
using namespace std;
unordered_map<int,int> mp;
typedef struct tagStudentinfo{  
	int niD;
	string   strName;  
  
}Studentinfo, *PStudentinfo; //学生信息  
  
class sorted{  
	public:  
    bool operator() (Studentinfo const &_A, Studentinfo const &_B) const  {  
        if(_A.niD < _B.niD)  
            return true;  
        if(_A.niD == _B.niD)  
            return _A.strName.compare(_B.strName) < 0;  
    return false;  
    }  
}; 
 map<Studentinfo, int, sorted>mapStudent;  
 /******************************/
 
 
typedef struct ip_tuple
{
    int src_port;
    int dst_port;
    char* src_ip;
 
    bool operator <(const ip_tuple& other) const
    {
        if (src_port < other.src_port)        //src_port按升序排序
        {
            return true;
        }
        else if (src_port == other.src_port)  //src_port相同，按dst_port升序排序
        {
            if(dst_port < other.dst_port)
            {
                return true;
            }
            else if(dst_port == other.dst_port)//dst_port,src_port相同，比较src_ip
            {
                if(strcmp(src_ip,other.src_ip)!=0)
                {
                    return true;
                }
            }
 
        }
        return false;
    }
} IPTUPLE;
map<IPTUPLE, int>m_roadMap;
 /*********************************/
int main()
{
    int T;
    cin>>T;
    while(T--)
    {
        string fruit,place;
        int num,n;
        cin>>n;
        map<string,map<string,int> >a;     
        map<string,map<string,int> >::iterator p;     
        while(n--){
            cin>>fruit>>place>>num;
            a[place][fruit]+=num;
        }
        for(p=a.begin();p!=a.end();p++){
            cout<<p->first<<endl;
            map<string,int>::iterator p1;    
            for(p1=p->second.begin();p1!=p->second.end();p1++)
                cout<<"   |----"<<p1->first<<"("<<p1->second<<")"<<endl;
        }
        if(T) cout<<endl;
    }
    return 0;
}

https://www.cnblogs.com/fnlingnzb-learner/p/5833051.html