Toán rời rạc- Buổi 2

#include<conio.h>
#include<iostream>
#include<math.h>
#include<cstdlib>

using namespace std;

void maxmin()
{
int mang[10],n,max,min;
cout<<"Nhap n: ";
cin>>n;
for(int i=0;i<n;i++)
{
cout<<"\nmang["<<i<<"]= ";
cin>>mang[i];
}
max=mang[0];
min=mang[0];
cout<<"\nCac so vua nhap la:\t";
for(int i=0;i<n;i++)
cout<<mang[i]<<"\t";
for(int i=1;i<n;i++)
{
if(min>mang[i])
min=mang[i];
if(max<mang[i])
max=mang[i];
}
cout<<"\nMax la: "<<max;
cout<<"\nMin la: "<<min;
}

void ptb1()
{
float a,b;
cout<<"Nhap a: ";
cin>>a;
cout<<"Nhap b: ";
cin>>b;
if(a==0)
{
if(b==0)
cout<<"Phuong trinh co vo so nghiem!";
else
cout<<"Phuong trinh vo nghiem!";
}
else
cout<<"Phuong trinh co nghiem x="<<-b/a;
}

void ptb2()
{
float a1,b1,c1,d1;
cout<<"Nhap a: ";
cin>>a1;
cout<<"Nhap b: ";
cin>>b1;
cout<<"Nhap c: ";
cin>>c1;
if(a1==0)
{
if(b1==0)
{
if(c1==0)
cout<<"Phuong trinh co vo so nghiem!";
else
cout<<"Phuong trinh vo nghiem!";
}
else
cout<<"Phuong trinh co nghiem x="<<-c1/b1;
}
else
{
d1=b1*b1-4*a1*c1;
if(d1<0)
cout<<"Phuong trinh vo nghiem!";
else
{
if(d1>0)
{
cout<<"\nPhuong trinh co nghiem x1="<<(-b1+sqrt(d1))/(2*a1);
cout<<"\nPhuong trinh co nghiem x2="<<(-b1-sqrt(d1))/(2*a1);
}
else
cout<<"\nPhuong trinh co nghiem kep x="<<-b1/(2*a1);
}
}
}

void diem()
{
float diem;
cout<<"\nNhap diem toan roi rac: ";
cin>>diem;
if(diem>=8.5)
cout<<"\nDiem chu la: "<<"A";
else
{
if(diem>=7)
cout<<"\nDiem chu la: "<<"B";
else
if(diem>=5.5)
cout<<"\nDiem chu la: "<<"C";
else
if(diem>=4)
cout<<"\nDiem chu la: "<<"D";
else
cout<<"\nDiem chu la: "<<"F";
}

}

int main()
{
char t;
maxmin();
cout<<"\n\n---------------------------------\n";
ptb1();
cout<<"\n\n---------------------------------\n";
ptb2();
cout<<"\n\n---------------------------------\n";
diem();
cout<<"\n\nBan muon thoat khong? (y/n)\n";
cin>>t;
if(t=='y'||t=='Y')
getch();
else
{
main();
}
}