數據結構——兩個一元多項式之和

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

struct List{
	int coef;//係數
	int expn;//冪
	struct List * next;
};
typedef struct List * Link;
typedef struct List Lnode;

/*創建鏈表*/
Link create()
{
	int a, n, i = 1;
	Link head, s, p;
	head = (Link)malloc(sizeof(Lnode));
	head->next = NULL;
	p = head;
	do{
		printf("\n第%d次->係數，冪：",i++);
		scanf("%d %d", &a, &n);
		if (a != 0 || n != 0)
		{
			s = (Link)malloc(sizeof(Lnode));
			s->coef = a;
			s->expn = n;
			s->next = NULL;
			p->next = s;
			p = s;
		}
	} while (a != 0 || n != 0);
	printf("\n");
	return head->next;
}

/*進行相加操作*/
Link add(Link pa, Link pb)
{
	int n;
	Link pc, s, p;
	pc = (Link)malloc(sizeof(Lnode));
	pc->next = NULL;
	p = pc;
	while (pa != NULL&&pb != NULL)
	{
		if (pa->expn > pb->expn)
		{
			s = (Link)malloc(sizeof(Lnode));
			s->coef = pa->coef;
			s->expn = pa->expn;
			s->next = NULL;
			p->next = s;
			p = s;
			pa = pa->next;
		}
		else if (pa->expn < pb->expn)
		{
			s = (Link)malloc(sizeof(Lnode));
			s->coef = pb->coef;
			s->expn = pb->expn;
			s->next = NULL;
			p->next = s;
			p = s;
			pb = pb->next;
		}
		else
		{
			n = pa->coef + pb->coef;
			if (n != 0)
			{
				s = (Link)malloc(sizeof(Lnode));
				s->coef = n;
				s->expn = pb->expn;
				s->next = NULL;
				p->next = s;
				p = s;
			}
			pa = pa->next;
			pb = pb->next;
		}
	}
	while (pa != NULL)
	{
		s = (Link)malloc(sizeof(Lnode));
		s->coef = pa->coef;
		s->coef = pa->coef;
		s->next = NULL;
		p->next = s;
		p = s;
		pa = pa->next;
	}
	while (pb != NULL)
	{
		s = (Link)malloc(sizeof(Lnode));
		s->coef = pb->coef;
		s->coef = pb->coef;
		s->next = NULL;
		p->next = s;
		p = s;
		pb = pb->next;
	}
	return pc->next;
}

void display(Link head)
{
	int first = 1;
	Link p = head;
	while (p != NULL)
	{
		if (first)//顯示第一個結點時，不顯示+號
		{
			if (p->expn == 1)
			{
				printf("%dx", p->coef);
			}
			else if (p->expn == 0)
			{
				printf("%d", p->coef);
			}
			else
			{
				printf("%dx^%d", p->coef, p->expn);
			}
			first = 0;
		}
		else//顯示其他的結點，顯示+號
		{
			if (p->expn == 1)
			{
				printf("+%dx", p->coef);
			}
			else if (p->expn == 0)
			{
				printf("+%d", p->coef);
			}
			else
			{
				printf("+%dx^%d", p->coef, p->expn);
			}
		}
		p = p->next;
	}
	printf("\n");
}

int main()
{
	Link Link1, Link2, Link3;
	Link1 = create();
	Link2 = create();
	Link3 = add(Link1, Link2);
	display(Link1);
	display(Link2);
	display(Link3);
	system("pause");
	return 0;
}