Cộng Đa Thức

#include <iostream>
using namespace std;

struct Node
{
    int heso, somu;
    Node *pNext;
};
struct List
{
    Node *pHead, *pTail;
};

void AddHead(List &L, Node *p)
{
    if (L.pHead == NULL)
    {
        L.pHead = L.pTail = p;
    }
    else
    {
        p->pNext = L.pHead;
        L.pHead = p;
    }
}

void CreateList(List &L)
{
    L.pHead = L.pTail = NULL;
}

Node * CreateNode(int heso, int somu)
{
    Node *p = new Node;
    if (!p) exit(1);
    p->heso = heso;
    p->somu = somu;
    p->pNext = NULL;
    return p;
}

void NhapDaThuc(List &L)
{
    int x, y;
    int n;
    cout << "bac cua da thuc: ";
    cin >> n;
    do
    {
        cout << "he so: ";
        cin >> x;
        cout << "so mu: ";
        cin >> y;
        AddHead(L, CreateNode(x, y));
        n--;
    } while (n >= 0);
}

void AddDaThuc(List &L, Node *pAdd)
{
    Node *p = L.pHead;
    while (p != NULL && p->somu != pAdd->somu)
        p = p->pNext;
    if (p == NULL) AddHead(L, pAdd);
    else
    {
        p->heso += pAdd->heso;
        delete pAdd;
    }
}

void CongDaThuc(List &L, List &L1)
{
    Node *p = NULL;
    while (L1.pHead != NULL)
    {
        p = L1.pHead;
        L1.pHead = p->pNext;
        p->pNext = NULL;
        AddDaThuc(L, p);
    }
}
void Output(List L)
{
    Node *p = L.pHead;
    while (p)
    {
        cout << p->heso << " * x ^ " << p->somu << " + ";
        p = p->pNext;
    }
}
void main()
{
    List L1, L2;
    CreateList(L1);
    CreateList(L2);
    NhapDaThuc(L1);
    NhapDaThuc(L2);
    CongDaThuc(L1, L2);
    Output(L1);
}