Big number in linked list C++

Big number in linked list

#include <iostream>
#include <string.h>
using namespace std;

struct NODE
{
	int data;
	NODE *pNext, *pPred;
}; typedef struct NODE NODE;

typedef struct
{
	NODE *pHead, *pTail;
}LIST;

void Init(LIST &L)
{
	L.pHead = L.pTail = NULL;
}
template <class T>
NODE *CreateNode(T &x)
{
	NODE *newnode = new NODE;
	if (newnode == NULL) //Khong du bo nho cap phat
		return NULL;
	newnode->data = x;
	newnode->pNext = NULL;
	newnode->pPred = NULL;
	return newnode;
}
void AddHead(LIST &L, NODE *p)
{
	if (L.pHead == NULL)
	{
		L.pHead = L.pTail = p;
		return;
	}
	else
	{
		p->pNext = L.pHead;
		L.pHead->pPred = p;
		L.pHead = p;
	}
}
void AddTail(LIST &L, NODE *p)
{
	if (L.pHead == NULL)
	{
		L.pHead = L.pTail = p;
	}
	else
	{
		L.pTail->pNext = p;
		p->pPred = L.pTail;
		L.pTail = p;
	}
}
void DisplayHead(LIST L)
{
	if (L.pHead == NULL)
		return;
	for (NODE *p = L.pHead; p != NULL; p = p->pNext)
		cout << p->data;
}
void DeleteHead(LIST &L)
{
	if (L.pHead == NULL)
		return;
	else if (L.pHead == L.pTail)
	{
		delete L.pHead;
		Init(L);
	}
	else
	{
		NODE *p = L.pHead;
		L.pHead = L.pHead->pNext;
		delete p;
	}
}
int Count(LIST L)
{
	int count = 0;
	if (L.pHead == NULL)
		return count;
	for (NODE *p = L.pHead; p != NULL; p = p->pNext)
		count++;
	return count;
}

void Nhap2Chuoi(LIST &L, LIST &L2, char s[100], char s2[100])
{
	cout << "\nNhap So Thu Nhat:";
	fflush(stdin);
	gets(s);
	cout << "\nNhap So Thu Hai:";
	fflush(stdin);
	gets(s2);

	for (int i = 0; i < strlen(s); i++)
	{
		int temp = s[i] - 48;
		NODE *p = CreateNode(temp);
		AddTail(L, p);
	}
	for (int i = 0; i < strlen(s2); i++)
	{
		int temp2 = s2[i] - 48;
		NODE *q = CreateNode(temp2);
		AddTail(L2, q);
	}
}
void Nhap1Chuoi(LIST &L, char s[100])
{
	cout << "\nNhap So:";
	fflush(stdin);
	gets(s);
	for (int i = 0; i < strlen(s); i++)
	{
		int temp = s[i] - 48;
		NODE *p = CreateNode(temp);
		AddTail(L, p);
	}
}
void CanBangChuSo(LIST &L, LIST &L2)
{
	int k = 0, x = 0;
	int CountL = Count(L), CountL2 = Count(L2);
	if (CountL > CountL2)
	{
		k = CountL - CountL2;
		for (int i = 0; i < k; i++)
		{
			NODE *p = CreateNode(x);
			AddHead(L2, p);
		}
	}
	if (CountL2 > CountL)
	{
		k = CountL2 - CountL;
		for (int i = 0; i < k; i++)
		{
			NODE *q = CreateNode(x);
			AddHead(L, q);
		}
	}
}
void XoaSo0Du(LIST &L)
{

	if (L.pHead->data != 0)
		return;
	if (L.pHead->pNext == NULL)
		return;
	while (L.pHead->data == 0)
	{
		DeleteHead(L);
		if (L.pHead->pNext == NULL)
			return;
	}
}
LIST TinhTong(LIST L, LIST L2)
{
	LIST Tong;
	Init(Tong);
	int nho = 0, x;
	NODE *z;
	CanBangChuSo(L, L2);
	for (NODE *p = L.pTail, *q = L2.pTail;; p = p->pPred, q = q->pPred)
	{
		int temp = (p->data) + (q->data) + nho;
		nho = temp / 10;
		x = temp % 10;
		z = CreateNode(x);
		AddHead(Tong, z);
		if (q == L2.pHead)
			break;
	}
	if (nho != 0)
	{
		z = CreateNode(nho);
		AddHead(Tong, z);
	}
	return Tong;
}
LIST operator+(LIST L, LIST L2)
{
	LIST kq;
	Init(kq);
	kq = TinhTong(L, L2);
	return kq;
}
int SoSanh2So(LIST L, LIST L2)
{
	CanBangChuSo(L, L2);
	for (NODE *p = L.pHead, *q = L2.pHead; p != NULL; p = p->pNext, q = q->pNext)
	{
		if (p->data > q->data)  // Ket luan So Thu 1 > So Thu 2
			return 1;
		else if (p->data < q->data) //Ket luan So Thu 2 > So Thu 1
			return 2;
	}
	return 0;  // 2 so bang nhau
}
LIST TinhHieu(LIST L, LIST L2)
{
	CanBangChuSo(L, L2);
	LIST Hieu;
	Init(Hieu);
	int nho = 0, x;
	NODE *z;
	for (NODE *p = L.pTail, *q = L2.pTail;; p = p->pPred, q = q->pPred)
	{
		int temp = (p->data) - (q->data) - nho;
		if (temp < 0)
		{
			temp += 10;
			nho = 1;
		}
		else
		{
			nho = temp / 10;
		}
		x = temp % 10;
		z = CreateNode(x);
		AddHead(Hieu, z);
		if (q == L2.pHead)
			break;
	}
	XoaSo0Du(Hieu);
	return Hieu;
}
LIST operator-(LIST L, LIST L2)
{
	LIST kq;
	Init(kq);
	kq = TinhHieu(L, L2);
	return kq;
}
void RemoveList(LIST &L)
{
	if (L.pHead == NULL)
		return;
	while (L.pHead != NULL)
	{
		NODE *p = L.pHead;
		L.pHead = L.pHead->pNext;
		delete p;
	}
	Init(L);
}
LIST TinhTich(LIST L, LIST L2)
{
	int x, ZERO = 0, k, k2 = 0;
	NODE *z;
	LIST Tich, Sum;
	Init(Tich);
	Init(Sum);
	z = CreateNode(ZERO);
	AddHead(Sum, z);
	if (Count(L) > Count(L2))
		k = Count(L);
	else
		k = Count(L2);
	for (NODE *q = L2.pTail;; q = q->pPred)
	{
		int nho = 0;
		for (NODE*p = L.pTail;; p = p->pPred)
		{
			int temp = (p->data) * (q->data) + nho;
			nho = temp / 10;
			x = temp % 10;
			z = CreateNode(x);
			AddHead(Tich, z);
			if (p == L.pHead)
				break;
		}
		if (nho != 0)
		{
			z = CreateNode(nho);
			AddHead(Tich, z);
		}
		for (int i = 1; i <= k; i++)
		{
			z = CreateNode(ZERO);
			AddHead(Tich, z);
		}
		for (int j = 0; j < k2; j++)
		{
			z = CreateNode(ZERO);
			AddTail(Tich, z);
		}
		k--;
		k2++;
		Sum = Sum + Tich;
		RemoveList(Tich);
		if (q == L2.pHead)
			break;
	}
	XoaSo0Du(Sum);
	return Sum;
}
LIST operator*(LIST L, LIST L2)
{
	LIST kq;
	Init(kq);
	kq = TinhTich(L, L2);
	return kq;
}
LIST Thuong(LIST L, LIST L2)
{
	int x = 1;
	NODE *z;
	LIST Temp, thuong;
	Init(Temp);
	Init(thuong);
	for (NODE *p = L.pHead; p != NULL; p = p->pNext)
	{
		int x = p->data;
		int count = 0;
		z = CreateNode(x);
		AddTail(Temp, z);
		while (SoSanh2So(Temp, L2) != 2)
		{
			Temp = Temp - L2;
			count++;
		}
		z = CreateNode(count);
		AddTail(thuong, z);
	}
	XoaSo0Du(thuong);
	return thuong;
}
LIST operator/(LIST L1, LIST L2)
{
	return Thuong(L1, L2);
}
LIST TinhLuyThua(LIST L, int somu)
{
	LIST luythua;
	int ONE = 1;
	NODE *z;
	Init(luythua);
	z = CreateNode(ONE);
	AddHead(luythua, z);
	for (int i = 0; i < somu; i++)
	{
		luythua = luythua * L;
	}
	return luythua;
}
LIST TinhGiaiThua(LIST L)
{
	int ONE = 1;
	LIST gt, k;
	Init(gt);
	Init(k);
	NODE *z;
	z = CreateNode(ONE);
	AddHead(gt, z);
	AddHead(k, z);
	while (SoSanh2So(L, k) != 2)
	{
		gt = gt * L;
		L = L - k;
	}
	return gt;
}


int main()
{
	system("color 0a");
	int somu, chon;
	LIST L, L2;
	char s[100], s2[100];
	Init(L);
	Init(L2);
	LIST T, Tich, H, Thuong, LuyThua, GiaiThua;
	do{
		system("cls");
		cout << "\t\t|______________COPYRIGHT TUAN NGUYEN______________|\n";
		cout << "\t1.Tinh Tong 2 Chuoi So Nguyen Duong \n\n";
		cout << "\t2.Tinh Hieu 2 Chuoi So Nguyen Duong\n\n";
		cout << "\t3.Tinh Tich 2 Chuoi So Nguyen Duong\n\n";
		cout << "\t4.Tinh Thuong 2 Chuoi So Nguyen Duong\n\n";
		cout << "\t5.Tinh Luy Thua Chuoi So Nguyen Duong\n\n";
		cout << "\t6.Tinh Giai Thua Chuoi So Nguyen Duong\n\n";
		cout << "\t7.Ket thuc\n";
		cout << "Moi Ban Chon:\n";
		cin >> chon;
		switch (chon)
		{
		case 1:
		{
			Nhap2Chuoi(L, L2, s, s2); CanBangChuSo(L, L2); T = L + L2;
			cout << "\nTong = "; DisplayHead(T); RemoveList(L); RemoveList(L2); system("pause"); break;
		}

		case 2:
		{
			Nhap2Chuoi(L, L2, s, s2); CanBangChuSo(L, L2);
			if (SoSanh2So(L, L2) == 1 || SoSanh2So(L, L2) == 0)
			{
				H = L - L2; if (Count(H) == 0) cout << "Hieu = 0"; else cout << "\nHieu = ";
			}
			else if (SoSanh2So(L, L2) == 2)
			{
				H = L2 - L; if (Count(H) == 0) cout << "Hieu = 0"; else cout << "\nHieu = - ";
			}
			DisplayHead(H); RemoveList(L); RemoveList(L2); system("pause"); break;
		}
		case 3:
		{
			Nhap2Chuoi(L, L2, s, s2); CanBangChuSo(L, L2); Tich = L * L2;
			cout << "\nTich = ";
			if (Count(Tich) == 0)
				cout << "0";
			else
				DisplayHead(Tich); RemoveList(L); RemoveList(L2); system("pause"); break;
		}
		case 4:
		{
			Nhap2Chuoi(L, L2, s, s2); CanBangChuSo(L, L2); Thuong = L / L2;
			cout << "\nThuong = ";
			DisplayHead(Thuong); system("pause"); RemoveList(L); RemoveList(L2); break;
		}
		case 5:
		{
			Nhap1Chuoi(L, s);
			do
			{
				cout << "\nNhap Vao So Mu De Tinh Luy Thua:";
				cin >> somu;
				if (somu < 0)
					cout << "Nhap So Mu >=0!\n";

			} while (somu < 0); LuyThua = TinhLuyThua(L, somu); cout << "\n So Thu Nhat ^ " << somu << " = ";
			DisplayHead(LuyThua);  system("pause"); RemoveList(L); break;
		}
		case 6:
		{
			cout << "Nhap n:\n"; Nhap1Chuoi(L, s); GiaiThua = TinhGiaiThua(L);
			cout << "n! = "; DisplayHead(GiaiThua); system("pause"); RemoveList(L); break;
		}
		}
	}

	while (chon != 7);
	return 0;
}