C++ Object-Oriented Programming 044: Fill in the Blanks in Programming: Student Information in the Database ---- (Peking University Mooc)

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Special blog link

Peking University C++ POJ After-Class Exercises Blog Full Solution Record

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Advance

Beginner C++ is indeed for this question.
I am not very good at inheritance and some details.
This answer is based on the code of Delin Enbao.
After writing this question, all the questions of Peking University Mooc are almost finished
. I can't write about the world anymore. I'll
reprint it later.

This is also regarded as
a day after I first started to try to use C++ to brush Leetcode. If you do
n’t use C anymore, you have to get used to it
and then show C++ Prime.

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Original title

#include <iostream>
#include <string>
#include <map>
#include <iterator>
#include <algorithm>
using namespace std;
// 在此处补充你的代码
struct Student 
{
    
    
	string name;
	int score;
};
template <class T>
void Print(T first,T last) {
    
    
	for(;first!= last; ++ first)
		cout << * first << ",";
	cout << endl;
}
int main()
{
    
    
	
	Student s[] = {
    
     {
    
    "Tom",80},{
    
    "Jack",70},
					{
    
    "Jone",90},{
    
    "Tom",70},{
    
    "Alice",100} };
	
	MyMultimap<string,int> mp;
	for(int i = 0; i<5; ++ i)
		mp.insert(make_pair(s[i].name,s[i].score));
	Print(mp.begin(),mp.end()); //按姓名从大到小输出

	mp.Set("Tom",78); //把所有名为"Tom"的学生的成绩都设置为78
	Print(mp.begin(),mp.end());
	
	
	
	MyMultimap<int,string,less<int> > mp2;
	for(int i = 0; i<5; ++ i) 
		mp2.insert(make_pair(s[i].score,s[i].name));
	
	Print(mp2.begin(),mp2.end()); //按成绩从小到大输出
	mp2.Set(70,"Error");          //把所有成绩为70的学生，名字都改为"Error"
	Print(mp2.begin(),mp2.end());
	cout << "******" << endl;
	
	mp.clear();
	
	string name;
	string cmd;
	int score;		
	while(cin >> cmd ) {
    
    
		if( cmd == "A") {
    
    
			cin >> name >> score;
			if(mp.find(name) != mp.end() ) {
    
    
				cout << "erroe" << endl;
			}
			mp.insert(make_pair(name,score));
		}
		else if(cmd == "Q") {
    
    
			cin >> name;
			MyMultimap<string,int>::iterator p = mp.find(name);
			if( p!= mp.end()) {
    
    
				cout << p->second << endl;
			}
			else {
    
    
				cout << "Not Found" << endl; 
			}		
		}
	}
	return 0;
}

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Code

template<class key,class T,class Pred = greater<key> >
class MyMultimap:public multimap<key,T,Pred>
{
    
    
public:
    void Set(key str,T score)
    {
    
    
        typename multimap<key, T, Pred>::iterator p1,p2;
        p1 = multimap<key, T, Pred>::lower_bound(str) ;
        p2 = multimap<key, T, Pred>::upper_bound(str);
        for(;p1!= p2;p1++)
        {
    
    
            if(p1->first == str)
                p1->second = score;
        }
    }
};

template<class T1,class T2>
ostream& operator <<(ostream& os,const pair<T1,T2> & p)
{
    
    
    os<<'('<<p.first<<','<<p.second<<')';
    return os;
}