学籍管理

题源 map的基本操作

#include<bits/stdc++.h>
using namespace std;
int n,op,sc;
string name;
int main()
{
	map<string,int>m;
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>op;
		if(op==1){
			cin>>name>>sc;
			m[name]=sc;
			cout<<"OK"<<endl;
		}
		else if(op==2){
			cin>>name;
			if(m.find(name)==m.end()){
				cout<<"Not found"<<endl;
			}
			else{
				cout<<m[name]<<endl;
			}
		}
		else if(op==3){
			cin>>name;
			if(m.find(name)==m.end()){
				cout<<"Not found"<<endl;
			}
			else{
				m.erase(name);
				cout<<"Deleted successfully"<<endl;
			}
		}
		else{
			cout<<m.size()<<endl;
		}
	}
	return 0;
 }