一元多项式计算器

• 题目：多项式计算器要实现一元多项式运算，首先要设计表示一元多项式P的合适的数据结构，并支持多项式的下列运算

1. 建立多项式
2. 输出多项式
3. 两个多项式相加，建立并输出和多项式
4. 两个多项式相减，建立并输出差多项式

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

typedef struct node    //结构体
{
	int p;    //系数
	int power;     //指数
	struct node *next;
}LNode,*Linklist;

void PrintList(Linklist L)    //打印链表
{
	int a;
	L = L -> next;
	if(L -> power == 0)
	{
		printf("%d ",L -> p);
		L = L -> next;
	}
	else 
	{
		if(L -> p == 1  && L -> power != 1)
		{
			printf("X^%d ",L -> power);
	        L = L -> next;
		}
		else if(L -> power == 1 && L -> p != 1)
		{
			printf("%d * X ",L -> p,L -> power);
	        L = L -> next;
		}	
		else if(L -> p == 1 && L -> power == 1)
		{
			printf("X ",L -> p,L -> power);
	        L = L -> next;
		}
		else
		{
			printf("%d * X^%d ",L -> p,L -> power);
			L = L -> next;
		}
	}
	while(L != NULL)
	{
		if(L -> power != 0 && L -> p > 0)
		{
			printf("+ %d * X^%d ",L -> p,L -> power);
			L = L -> next;
		}
		else if (L -> p < 0)
		{
			a = 0 - L -> p;
			printf("- %d * X^%d ",a,L -> power);
			L = L -> next;
		}
	}
	printf("\n");
}

Linklist Listcreat()    //建立链表
{
	int p,power;
	Linklist L;
	LNode *r,*s;
	L = (Linklist)malloc(sizeof(LNode));
	r = L;
	printf("输入指数和系数：");
	scanf("%d,%d",&p,&power);    //输入系数和指数
	while(p != 0)
	{
		s = (Linklist)malloc(sizeof(LNode));
		s -> p = p;
		s -> power = power;
		r -> next = s;
		r = s;
		printf("输入指数和系数，当系数为零时结束输入：");
		scanf("%d,%d",&p,&power);
	}
	r -> next = NULL;
	return L;
}

Linklist Listadd(Linklist La,Linklist Lb)    //多项式相加
{
	Linklist a = La -> next;
	Linklist b = Lb -> next;
	Linklist H,pc,qc;
	pc = (Linklist)malloc(sizeof(LNode));
	pc -> next = NULL;
	H = pc;
	while(a != NULL && b != NULL)     //两个链表未扫描完时
	{
		qc =(Linklist) malloc(sizeof(LNode));
		if(a -> power < b -> power)     //la中指数小于lb中指数
		{
			qc -> p = a -> p;
			qc -> power = a -> power;
			a = a -> next;
		}
		else if(a -> power == b -> power)
		{
			qc -> p = a -> p + b -> p;
			qc -> power = a -> power;
			a = a -> next;
			b = b -> next;
		}
		else
		{
			qc -> p = b -> p;
			qc -> power = b -> power;
			b = b -> next;
		}
		if(qc -> p != 0)
		{
			qc -> next = pc -> next;
			pc -> next = qc;
			pc = qc;
		}
		else free(qc);
	} 
	while(a != NULL)
	{
		qc = (Linklist)malloc(sizeof(LNode));
		qc -> p = a -> p;
		qc -> power = a -> power;
		a = a -> next;
		qc -> next = pc -> next;
		pc -> next = qc;
		pc = qc;
	}
	while(b != NULL)
	{
		qc = (Linklist)malloc(sizeof(LNode));
		qc -> p = b -> p;
		qc -> power = b -> power;
		b = b -> next;
		qc -> next = pc -> next;
		pc -> next = qc;
		pc = qc;
	}
	return H;
}

Linklist Listsubtraction(Linklist La,Linklist Lb)    //多项式相减
{
	Linklist H = Lb;
	Linklist b = Lb -> next;
	while(b -> next != NULL)
	{
		b -> p = (-1) * b -> p;
		b = b -> next;
	}
	Linklist Q = Listadd(La,H);
	return Q;
}

Linklist Listderivatives(Linklist L)     //多项式求导
{
	Linklist a = L -> next;
	Linklist H;
	LNode *r,*s;
	r = (Linklist)malloc(sizeof(LNode));
	r -> next = NULL;
	H = r;
	while(a != NULL)
	{
		s = (Linklist)malloc(sizeof(LNode));
		if(a -> power == 0)
		{
			a = a -> next;
		}
		else
		{
			s -> p = a -> p * a -> power;
			s -> power = a -> power - 1;
			r -> next = s;
			r = s;
			a = a -> next;
		}
		r -> next = NULL;
	}
	return H;
}

void main()
{
	Linklist la,lb,P,Q,R,S;
	printf("输入多项式la数据\n");
	la = Listcreat();
	printf("输入多项式lb数据\n");
	lb = Listcreat();
	printf("la = ");
	PrintList(la);     //打印la
	printf("lb = ");
	PrintList(lb);     //打印lb
	printf("la + lb = ");
	P = Listadd(la,lb);      //la和lb相加
	PrintList(P);
	printf("la - lb = ");
	Q = Listsubtraction(la,lb);      //la和lb相减
	PrintList(Q);
	printf("la' = ");
	R = Listderivatives(la);      //la求导
	PrintList(R);
	printf("lb' = ");
	S = Listderivatives(lb);     //lb求导
	PrintList(S);
}