#include<stdio.h>  
#include<stdlib.h>
#include<malloc.h>

typedef int ElemType;

typedef struct Node *PloyNode;
typedef struct Node *PloyList;

/*結構體*/
struct Node
{
	int coef;
	int expn;
    PloyNode next;
};

/*帶表頭的單向連結串列*/
void CreatePloy(PloyList &L ,int n)
{
	int i;
	PloyNode p,q;
    L=(PloyList)malloc(sizeof(struct Node));  //生成頭結點
	L->coef=0;
	L->expn=0;
	L->next=NULL;              //初始化頭結點
	printf("輸入多項式每項係數和冪\n");

	q=L;
	for(i=0;i<n;i++)
	{
		p=(PloyList)malloc(sizeof(struct Node));
		scanf("%d%d",&p->coef,&p->expn);
		q->next=p;
		q=q->next;
	}
	q->next=NULL;
}

/* 輸出多項式*/
void PolyShow(PloyList L, void(*vi)(ElemType ,ElemType ))
{
	PloyList p=L->next;
	
	while(p)
	{
		vi(p->coef ,p->expn);
	    if(p->next)
		{
	  	    printf("+");
		}
	    p=p->next;
	}
	printf("\n");
}

void visit(ElemType coef, ElemType expn)
{
	if(coef!=0)
	{
		printf("%dX^%d",coef,expn);
	}
}

PloyList AddPloy(PloyList La,PloyList Lb)
{
	PloyList Lc;
	PloyNode Pa,Pb,Pc;
	Pa=La->next;
	Pb=Lb->next;

    Lc=(PloyList)malloc(sizeof(struct Node));  //生成頭結點
	Lc->coef=0;
	Lc->expn=0;
	Lc->next=NULL; 
	
	Pc=Lc;
	while(Pa!=NULL&&Pb!=NULL)
	{
		if(Pa->expn > Pb->expn) //取係數小的那一項
		{
			Pc->next=Pb;
			Pb=Pb->next;
		}
		else if(Pa->expn < Pb->expn) //取係數小的那一項
		{
			Pc->next=Pa;
			Pa=Pa->next;
		}
		else
		{
			Pa->coef=Pa->coef+Pb->coef;
			Pc->next=Pa;
			Pb=Pb->next;
			Pa=Pa->next;
		}
		Pc=Pc->next;
	} //while end

	while(Pa!=NULL)
	{
		Pc->next=Pa;
		Pc=Pc->next;
		Pa=Pa->next;
	}
	while(Pb!=NULL)
	{
		Pc->next=Pb;
		Pc=Pc->next;
		Pb=Pb->next;
	}

	return Lc;
}

int main()
{
	PloyList a, b, c;  //因為a,b,c只是宣告，沒有一個地址指向，所以前面需要用到引用
	printf("輸入多項式a, ");
	CreatePloy(a,5);

	printf("輸入多項式b, ");
	CreatePloy(b,5);

	printf("多項式a :");  
    PolyShow(a, visit);  
    printf("\n");  
    printf("多項式b :");  
    PolyShow(b, visit);  
    printf("\n");  

	c = AddPloy(a,b);  
    PolyShow(c, visit);  

	return 0;
}