多项式求和

[不想上班的一天又一天]

#include<stdio.h>
#include<stdlib.h>
#define LEN sizeof(Polynode)

//节点类型定义
typedef struct Polynode{
  int coef;
  int expn;
  struct Polynode * next;
}Polynode,*Polylist;//开辟列表


//建立一元多项式链表,尾插法
Polylist PolyCreate(){
	Polynode *head,*rear,*s;
	int coef,expn;//系数，指数
	head=(Polynode *) malloc (sizeof(Polynode));//建立头结点
	rear=head;
	scanf("请输入多项式的系数和指数项：%d,%d",&coef,&expn);
	while (coef!=0){
		s=(Polynode *)malloc(sizeof(Polynode));//申请新的结点
		s->coef=coef;
		s->expn=expn;
		rear->next=s;//在当前表尾做插入
		rear=s;
		scanf("%d,%d",&coef,&expn);
	}
	rear->next=NULL;
	return(head);

}

/*
遍历表p,每一个结点与s比较指数(查找)
若相同，q指向相同指数项的结点，返回1
若不相同，根据s所指指数大小在链表p中的位置来确定q的指向结点，返回0	
*/
int LocateElem(Polylist p,Polylist s,Polylist &q){
	Polylist p1=p->next;
	Polylist p2=p;//存储每一个多项式
	while(p1){
		if(s->expn > p1->expn){
			p1=p1->next;
			p2=p2->next;
		}else if(s->expn==p1->expn){
			q=p1;
			return 1;
		}else{
			q=p2;
			return 0;
		}
	}
	if(!p1){
		q=p2;
		return 0;
	}
	return 0;
}

//创建带头结点的链表
void CreatePoly(Polylist &p,int m){
	Polylist s,q;
	int i;
	p=(Polylist )malloc(LEN);
	p->next=NULL;
	for(i=0;i<m;i++){
		s=(Polylist ) malloc (LEN);
		printf("请输入系数和指数(以空格隔开)：");
		scanf("%d %d",&s->coef,&s->expn);
		if(!LocateElem(p,s,q)){
			s->next=q->next;
			q->next=s;
		}else{
			q->coef+=s->coef;
		}
	}
}

//比较两结点指数大小，根据情况返回不同的值
int cmp(Polylist pa,Polylist pb){
	if(pa->expn < pb->expn) return -1;
	else if(pa->expn == pb->expn) return 0;
	else return 1;
}

//两个多项式相加得一个新多项式，并且返回新多项式的头结点的指针
//指数递增
Polylist AddPoly(Polylist pa,Polylist pb){	//pa,pb均指向头结点
	Polylist newP,p,q,s,pc;
	int sum;
	p=pa->next;
	q=pb->next;
	newP=(Polylist)malloc(LEN);
	pc=newP;
	while(p&&q){
		switch(cmp(p,q)){
		case -1:
			s=(Polylist)malloc(LEN);//申请一个新结点
			s->coef=p->coef;
			s->expn=p->expn;
			pc->next=s;	//在新表中插入结点
			pc=s;
			p=p->next;//指针移动
			break;
		case 0:
			sum=p->coef+q->coef;
			if(sum!=0){
				s=(Polylist)malloc(LEN);
				s->coef=sum;
				s->expn=p->expn;
				pc->next=s;
				pc=s;
			}
			p=p->next;
			q=q->next;
			break;
		case 1:
			s=(Polylist)malloc (LEN);
			s->coef=q->coef;
			s->expn=q->expn;
			pc->next=s;
			pc=s;
			q=q->next;
			break;
		}
	}
	pc->next=p?p:q;
	return newP;
}
	
//打印输出一元多项式PL
void PrintPoly(Polylist PL){
	Polylist s;
	s=PL->next;
	while(s){
		printf("%d X^%d",s->coef,s->expn);
		s=s->next;
		if(s!=NULL)
			if(s->coef>=0) printf(" +");
	}
	printf("\n");
}

int main(){
    Polylist PA,PB,PC;
    int la,lb;
    printf("请输入第一个多项式PA的项数：");
    scanf("%d",&la);
	CreatePoly(PA,la);
	printf("第一个多项式为：");
    PrintPoly(PA);

	printf("请输入第二个多项式PB的项数：");
    scanf("%d",&lb);
	CreatePoly(PB,lb);
	printf("第二个多项式为：");
    PrintPoly(PB);

	printf("两个多项式相加： ");
	PC=AddPoly(PA,PB);
	PrintPoly(PC);

	return 0;
}

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