#include<bits/stdc++.h>
using namespace std;
int main(){
    //
    set<int>s;
    map<string,int>m;
    set<int>::iterator it_s;
    map<string,int>::iterator it_m;
    s.insert(1);
    s.insert(2);
    s.insert(3);
    s.insert(1);
    cout<<"set:"<<s.size()<<'\n';
    for(it_s=s.begin();it_s!=s.end();it_s++)
        printf("%d ",*it_s);
    printf("\ns.begin:%d",*s.begin());
    printf("\ns.rbegin:%d",*s.rbegin());
    printf("\ns.end:%d",*s.end());
    printf("\ns.rend:%d",*s.rend());
    printf("\n--s.end:%d",*--s.end());
    printf("\n--s.rend:%d",*--s.rend());
    m["a"]=1,m["b"]=2;
    m["c"]=3,m["d"]=4;
    m["A"]=27,m["B"]=28;
    m["C"]=29,m["D"]=30;
    printf("\nmap:size=%d\n",m.size());
    for(it_m=m.begin();it_m!=m.end();it_m++)
        cout<<it_m->first<<':'<<it_m->second<<' ';
    cout<<endl<<"m.begin="<<m.begin()->first<<':'<<m.begin()->second;
    cout<<endl<<"m.end="<<m.end()->first<<':'<<m.end()->second;
    cout<<endl<<"m.rbegin="<<m.rbegin()->first<<':'<<m.rbegin()->second;
    cout<<endl<<"m.rend="<<m.rend()->first<<':'<<m.rend()->second;
    return 0;
}

没输出