Câu 3 cuối kì OOP Đại học CNTT

//https://www.facebook.com/pages/C%C3%B9ng-h%E1%BB%8Dc-l%E1%BA%ADp-tr%C3%ACnh/632038696941833
#include <iostream>
#include <string>
using namespace std;

class SinhVien
{
protected:
	string MSSV, HoTen, DiaChi;
	int TongChi;
	float DTB;
	virtual void Input(istream &in) = 0;
	virtual void Output(ostream &out) const = 0;
public:
	friend istream& operator >> (istream& in, SinhVien &SV)
	{
		fflush(stdin);
		cout << "Ten: ";
		getline(in, SV.HoTen);
		cout << "MSSV: ";
		getline(in, SV.MSSV);
		cout << "Dia Chi: ";
		getline(in, SV.DiaChi);
		cout << "Tong Chi: ";
		in >> SV.TongChi;
		cout << "DTB: ";
		in >> SV.DTB;
		SV.Input(in);
		return in;
	}
	friend ostream& operator << (ostream& out, const SinhVien &SV)
	{
		fflush(stdin);
		out << "Ten: " << SV.HoTen << endl;
		out << "MSSV: " << SV.MSSV << endl;
		out << "Dia Chi: " << SV.DiaChi << endl;
		out << "Tong Chi: " << SV.TongChi << endl;
		out << "DTB: " << SV.DTB << endl;
		SV.Output(out);
		return out;
	}
	virtual int XetTotNghiep() = 0;
	float GetDTB(){ return this->DTB; }
	int KieuSinhVien;
};

class SVDH : public SinhVien
{
private:
	string TenLuanVan;
	float DiemLV;
public:
	void Input(istream &in)
	{
		fflush(stdin);
		cout << "Ten Luan Van: ";
		getline(in, this->TenLuanVan);
		cout << "Diem Luan Van: ";
		in >> this->DiemLV;
	}
	void Output(ostream &out) const
	{
		out << "Ten Luan Van: " << this->TenLuanVan << endl;
		out << "Diem Luan Van: " << this->DiemLV << endl;
	}
	int XetTotNghiep()
	{
		if (this->TongChi >= 170 && this->DiemLV >= 5.0 && this->DTB >= 5.0) return 1;
		return 0;
	}

};

class SVCD : public SinhVien
{
private:
	float DiemTN;
public:
	void Input(istream &in)
	{
		cout << "Diem Tot Nghiep: ";
		in >> this->DiemTN;
	}
	void Output(ostream &out) const
	{
		out << "Diem Tot Nghiep: " << this->DiemTN << endl;
	}
	int XetTotNghiep()
	{
		if (this->TongChi >= 120 && this->DiemTN >= 5.0 && this->DTB >= 5.0) return 1;
		return 0;
	}

};

void main()
{
	SinhVien **SV = NULL;
	int SoSinhVien, LuaChon;
	do
	{
		system("cls");
		cout << "So Sinh Vien Can Nhap: ";
		cin >> SoSinhVien;
	} while (SoSinhVien <= 0);
	SV = new SinhVien*[SoSinhVien];

	for (int i = 0; i < SoSinhVien; i++)
	{
		system("cls");
		cout << " Nhap SV thu: " << i + 1 << endl;
		do
		{
			cout << "1. Dai Hoc\n2. Cao Dang\n\tLua chon: ";
			cin >> LuaChon;
		} while (LuaChon <= 0 || LuaChon >= 3);
		switch (LuaChon)
		{
		case 1:
			SV[i] = new SVDH;
			break;
		case 2:
			SV[i] = new SVCD;
			break;
		}
		SV[i]->KieuSinhVien = LuaChon;
		cin >> *SV[i];
	}

	int SVTN = 0;
	for (int i = 0; i < SoSinhVien; i++)
	{
		if (SV[i]->XetTotNghiep() == 1) SVTN++;
	}
	cout << "So SV duoc tot nghiep: " << SVTN << endl;
	float max = -1;
	for (int i = 0; i < SoSinhVien; i++)
	{
		if (SV[i]->KieuSinhVien == 1)
		{
			if (max < SV[i]->GetDTB())
			{
				max = SV[i]->GetDTB();
			}
		}
	}
	if (max < 0) cout << "Ca truong deu thap diem, cu the DTB = 0\n";
	else cout << "SV Dai Hoc Co DTB Cao Nhat: " << max << endl;
}