6-3 Add Two Polynomials (20 points) (with test points)

Write a function to add two polynomials. Do not destroy the input. Use a linked list implementation with a dummy head node. Note: The zero polynomial is represented by an empty list with only the dummy head node.

Format of functions:

Polynomial Add( Polynomial a, Polynomial b );
where Polynomial is defined as the following:

typedef struct Node *PtrToNode;
struct Node {
    
    
    int Coefficient;
    int Exponent;
    PtrToNode Next;
};
typedef PtrToNode Polynomial;
/* Nodes are sorted in decreasing order of exponents.*/  

The function Add is supposed to return a polynomial which is the sum of a and b.

Sample program of judge:

#include <stdio.h>
#include <stdlib.h>
typedef struct Node *PtrToNode;
struct Node  {
    
    
    int Coefficient;
    int Exponent;
    PtrToNode Next;
};
typedef PtrToNode Polynomial;

Polynomial Read(); /* details omitted */
void Print( Polynomial p ); /* details omitted */
Polynomial Add( Polynomial a, Polynomial b );

int main()
{
    
    
    Polynomial a, b, s;
    a = Read();
    b = Read();
    s = Add(a, b);
    Print(s);
    return 0;
}

/* Your function will be put here */

Sample Input:

4
3 4 -5 2 6 1 -2 0
3
5 20 -7 4 3 1

Sample Output:

5 20 -4 4 -5 2 9 1 -2 0

① A linked list with a head node, where the data is actually stored is the next node

②The nodes whose coefficient sum is 0 are skipped, and are not regarded as nodes in the result list

③Tmp temporary node should be reapplied every time in the loop

Polynomial Add( Polynomial a, Polynomial b ){
    
    
	Polynomial p = a->Next;
	Polynomial q = b->Next;
	Polynomial res = (Polynomial)malloc(sizeof(struct Node));
	Polynomial head = res;
	while(p&&q){
    
    
        Polynomial tmp = (Polynomial)malloc(sizeof(struct Node));
		if(p->Exponent==q->Exponent){
    
    
			tmp->Exponent = p->Exponent;
			tmp->Coefficient = p->Coefficient + q->Coefficient;
			p = p->Next;
			q = q->Next;
			if(tmp->Coefficient!=0){
    
    
                res->Next = tmp;
                res = tmp;
            }
		}
		else if(p->Exponent<q->Exponent){
    
    
			tmp->Exponent = q->Exponent;
			tmp->Coefficient = q->Coefficient;
			q = q->Next;
			res->Next = tmp;
            res = tmp;
		}
		else{
    
    
			tmp->Exponent = p->Exponent;
			tmp->Coefficient = p->Coefficient;
			p = p->Next;
			res->Next = tmp;
            res = tmp;
		}
	}
	if(p)
        res->Next = p;
    if(q)
        res->Next = q;
	return head;
}