int num; //總學生人數

class student {
friend class studentMessage;
private:
string ID;
string name;
double score[5]; //1-4代表math、English、OPP和總成績 ，0號單元空出
student * next;
public:
student();
string getName(){return name;}
string getID(){return ID;}
double getMath(){return score[1];}
double getEnglesh(){return score[2];}
double getOPP(){return score[3];}
double gettotol(){return score[4];}
student* getNext(){return next;}

static void analyse(int ,student * ); //分析成績
void display();                          //打印成績
void swap();                          //交換對象和對象->next的信息

};

student::student()
{
cout<<"請輸入學生學號 : ";cin>>ID;
cout<<"請輸入學生姓名 : ";cin>>name;
cout<<"請輸入學生的數學、英語和OPP成績 : "<<endl;
int a,b,c;
cin>>a;
while(a<0||a>100)
{
cout<<"輸入成績有誤，請重新輸入: "<<endl;
cin>>a;
}
cin>>b;
while(b<0||b>100)
{
cout<<"輸入成績有誤，請重新輸入: "<<endl;
cin>>b;
}
cin>>c;
while(c<0||c>100)
{
cout<<"輸入成績有誤，請重新輸入: "<<endl;
cin>>c;
}
score[1]=a;
score[2]=b;
score[3]=c;
score[4]=a+b+c;
next=NULL;
}

void student::analyse(int a,student * first)
{
int you=0,liang=0,zhong=0,jige=0,bujige=0;
student * t=first;
double average=0; //平均分
while(t)
{
int b = int(t->score[a]/10);
switch(b)
{
case 10:
case 9:you++;break;
case 8:liang++;break;
case 7:zhong++;break;
case 6:jige++;break;
default:bujige++;
}
average+=t->score[a];
t=t->next;
}
average=average/num;
cout<<" 考生總人數 : "<<num<<" 平均分 : "<<average<<endl;
cout<<"\n 優 良 中 及格 不及格 "<<endl;
cout<<" "<<you<<" \t"<<liang<<" \t"<<zhong<<"\t"<<jige<<"\t"<<bujige<<endl;
}

void student::display()
{
cout<<" "<<setw(3)<<ID<<" "<<setw(3)<<name<<" ";
for (int i=1;i<=4;i++)
{
cout<<setw(3)<<score[i]<<" ";
}
cout<<endl;
}

void student::swap()
{
int j;
string na,id;
double sco[5];
na=name;name=next->name;next->name=na;
id=ID;ID=next->ID;next->ID=id;
for(j=1;j<=4;j++)
{
sco[j]=score[j];
score[j]=next->score[j];
next->score[j]=sco[j];
}
}

class studentMessage{
private:
student * first;
student * last;
public:
studentMessage();
student* getFirst(){return first;}
student* getLast(){return last;}
int getNum(){return num;}
void add(); //向表中增加學生成績記錄
void search(); //在表中查找學生成績記錄
void del(); //在表中刪除學生成績記錄
void showOne(); //分析一門課的成績
void showAll(); //輸出所有同學所有科目的成績
void sort(); //按一門課成績或總成績排序
void clear(); //清空所有信息并退出系統

};

studentMessage::studentMessage()
{
first=NULL;
last=NULL;
num=0;
}

void studentMessage::add()
{
student * t =new student;
student *p = first;
while(p){
if(p->IDt->ID)
{
cout<<"\n學號輸入錯誤或該學生成績已經存在！(如需修改，請先刪除再重新錄入)"<<endl;
return;
}
p=p->next;
}
num++;
if(firstNULL)
{
first=last=t;

}
else
{
    last->next=t;
    last=last->next;
}

}

void studentMessage::search()
{
string a;
cout<<"\n請輸入要查找的學生的學號:";cin>>a;
student *t = first;
while(t){
if(t->ID==a)
break;
t=t->next;
}
if(!t)
{
cout<<"\n未找到要查找學生！"<<endl;
return;
}
cout<<"\n查找成功！"<<endl;
cout << " 學號 姓名 數學 英語 OPP 總成績" << endl;
t->display();
}

void studentMessage::del()
{
string a;
cout<<"\n請輸入要刪除的學生的學號: ";cin>>a;
student *t = first;
student *p=NULL;
while(t){
if(t->ID==a)
break;
p=t;
t=t->next;
}
if(!t)
{
cout<<"\n未找到要刪除學生！"<<endl;
return;
}
if(!p)
{
first=first->next;
cout<<"\n成功刪除學生"<<a<<endl;
delete t;
}
else
{
p->next=t->next;
cout<<"成功刪除學生"<<a<<endl;
delete t;
}

num--;

}

void studentMessage::showOne()
{
int a;
while(1)
{
cout<<"\n想要分析哪一門成績？請輸入相應序號(1:math 2:English 3:OPP): ";cin>>a;
if(a!=1&&a!=2&&a!=3)
cout<<"\n輸入序號有誤，請重新輸入！"<<endl;
else
break;
}
cout<<"\n\t成績分析如下: \n"<<endl;
student::analyse(a,first);
}

void studentMessage::showAll()
{
cout << "---------------------成績列表----------------------"<< endl;
cout << " 學號 姓名 數學 英語 OPP 總成績" << endl;
student *t = first;
while(t){
t->display();
t=t->next;
}
}

void studentMessage::sort()
{
int a,n=0; //n--排名
cout<<"想要按照什么成績排序？請輸入相應序號(1.數學 2.英語 3.OPP 4.總成績): ";
while(1)
{
cin>>a;
if (a!=1&&a!=2&&a!=3&&a!=4)
cout<<"\n輸入序號有誤，請重新輸入 : ";
else
break;
}
student *t=first;
student *p=t;
while(p->next)
{
t=first;
while(t->next)
{
if(t->next->score[a]>=t->score[a])
{
t->swap();
}
t=t->next;
}
p=p->next;
}
t = first;
cout<<"\n\t 成績表如下: "<<endl;
cout<<"學號 姓名 成績 排名"<<endl;
while(t){
n++;
cout<<" "<getID()<<" \t"<getName()<<" \t";
switch(a)
{
case 1 :cout<getMath()<<" \t"<<n<<endl;break;
case 2 :cout<getEnglesh()<<" \t"<<n<<endl;break;
case 3 :cout<getOPP()<<" \t"<<n<<endl;break;
case 4 :cout<gettotol()<<" \t"<<n<<endl;break;
}
t=t->next;
}
}

void studentMessage::clear()
{
int x;
cout<<"確認要清空所有信息？請輸入1或2 (1:確認 2:取消) : ";cin>>x;
if (x==2)
{
cout<<"\n取消清空\n"<<endl;
return;
}
student *t = first;
student *p;
while(t){
p=t;
t=t->next;
delete p;
}
cout<<"\n清空成功！\n";
cout<<"退出成功！\n";
}

void showMenu()
{
cout << " \n";
cout << "=\n";
cout << " 學生成績管理系統\n\n";
cout << " 1.顯示所有學生成績\n";
cout << " 2.添加信息\n";
cout << " 3.查詢信息\n";
cout << " 4.刪除信息\n";
cout << " 5.成績排序\n";
cout << " 6.單科成績分析\n";
cout << " 7.清空所有信息并退出系統\n";
cout << " 0.退出系統\n";
cout << "=\n";
cout << " \n";
}

int main()
{
int h;
studentMessage stuM=studentMessage();
while(1)
{
showMenu();
cout << "請輸入操作對應的序號 : ";
cin >>h;
cout<<endl;
switch(h)
{
case 1: stuM.showAll(); break;
case 2: stuM.add(); break;
case 3: stuM.search(); break;
case 4: stuM.del(); break;
case 5: stuM.sort(); break;
case 6: stuM.showOne(); break;
case 7: stuM.clear(); return 0;
case 0: cout<<"\n退出成功！";return 0;
default:cout<<"\n輸入序號有誤！請輸入正確的序號。"<<endl;
}
}
}