我想用链表实现两个多项式的相加操作
例： L1=2X^3+4X^5+6X^7
     L2=3X^4+4X^5
求L1+L2的表达式
但是出现问题了
 
下面是我写的代码   各位有空帮忙看下 

#include <iostream.h> 

typedef struct node
{
    int data;
    int n;
    node* next;
}node;
node* createlist(char n[])
{    int i=0;
    node *head,*t,*end;
    head=new node;
    end=head;
    t=end;
    cout<<"请输入"<<n<<"的第"<<i+1<<"项的系数（输入0为结束）  ";
    cin>>t->data;
    if(t->data!=0)
    {    cout<<"请输入"<<n<<"的第"<<i+1<<"项的次幂                ";
        cin>>t->n;
        i++;
    }
    else
    {
        delete t;end=NULL;end->next=NULL;head=NULL;return head;
    }

    while(t->data!=0)
    {
            end=t;
        t=new node;
        cout<<"请输入"<<n<<"的第"<<i+1<<"项的系数（输入0为结束）  ";
        cin>>t->data;
        if(t->data==0)
        {delete t;end->next=NULL;return head;}
        cout<<"请输入"<<n<<"的第"<<i+1<<"项的次幂                ";
        cin>>t->n;
        i++;
        end->next=t;
    }
    delete t;
    end->next=NULL;
    return head;
}
void dispaly(node *L,char n[])
{    cout<<n<<":    ";
    if(L==NULL)
    {
        cout<<"链表为空！";
    }
    else
        while(L!=NULL)
        {
            cout<<L->data<<"X^"<<L->n;            
            L=L->next;
            if(L!=NULL)
                cout<<"+";
        }
    cout<<endl;
}
node *addlist(node *p1,node *p2)
{    int i=0;
    node *head,*end,*t;
    head=new node;
    end=head;
    t=end;
    while(p1!=NULL&&p2!=NULL)
    {
        if(p1->n<p2->n) 
        {
            t->data=p1->data;
            t->n=p1->n;
            end=t;
            t=new node;
            end->next=t;
            p1=p1->next;
        }
        if(p1->n>p2->n)
        {
            t->data=p2->data;
            t->n=p2->n;
            end=t;
            t=new node;
            end->next=t;
            p2=p2->next;
        }
        if(p1->n==p2->n)
        {
            t->data=p1->data+p1->data;
            t->n=p1->n;
            end=t;
            t=new node;
            end->next=t;
            p2=p2->next;
            p1=p1->next;
        }
    }
    if(p1==NULL)
    {    while(p2!=NULL)
        {
            t->data=p2->data;
            t->n=p2->n;
            end=t;
            t=new node;
            end->next=t;
            p2=p2->next;
        }
    }
    if(p2==NULL)
    {    while(p1!=NULL)
        {
            t->data=p1->data;
            t->n=p1->n;
            end=t;
            t=new node;
            end->next=t;
            p1=p1->next;
        }
    }
    delete t;
    end->next=NULL;
    return head;
}
void main()
{
    node *p1=createlist("L1");
    node *p2=createlist("L2");
    dispaly(p1,"L1");
    dispaly(p2,"L2");
    node *p3=addlist(p1,p2);
    dispaly(p3,"L1+L2");
}