一元多项式的运算
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以一元多项式加法运算为例:
A,B可用线性链表可以表示为:
“和多项式”链表如下(图中的长方框表示已经被释放的结点):
#include <stdio.h> #include <stdlib.h> typedef struct Polyn{ int data; int index; struct Polyn *next; }Polyn,*Polynlist; void CreatPolyn(Polynlist &p,int m)//输入m项的系数和指数,建立一元多项式P { //有头结点 Polyn *q=p; for(int i=0;i<m;i++) { q->next=(Polyn*)malloc(sizeof(Polyn)); q=q->next; // printf("第%d项系数、指数:",i+1); scanf("%d%d",&q->data,&q->index); } q->next=0; } void PrintPolyn(Polynlist &p)//打印一元多项式P { Polyn *q=p->next; //(x^0)和(x^1)要做特别处理 if(q->index == 0) { printf("%d",q->data); //可能第二项指数为x q=q->next; if(q && q->index == 1) { if(q->data != 1) printf("%+dx",q->data);//正数则在前面加+,否则不加 else printf("+x"); q = q->next; } } else if(q->index == 1){ if(q->data != 1) printf("%dx",q->data); else printf("x"); q = q->next; } else{ printf("%dx^%d",q->data,q->index); q = q->next; } while(q) { printf("%+dx^%d",q->data,q->index); q=q->next; } printf("\n"); } void CopyPolyn(Polynlist &q,Polyn *r)//空指针必须引用去创建,新开辟结点链表并复制(数据域和指针域) { q = (Polyn *)malloc(sizeof(Polyn)); Polyn *q1 = q,*r1 = r->next; while(r1) { q1->next = (Polyn *)malloc(sizeof(Polyn)); q1 = q1->next; q1->data = r1->data; q1->index = r1->index; r1 = r1->next; } q1->next = NULL; } void ShowMenu() { printf("\t\t\t1.多项式相加\n"); printf("\t\t\t2.多项式相减\n"); printf("\t\t\t3.多项式相乘\n"); printf("\t\t\t4.退出\n"); } void AddPolyn(Polyn *p,Polyn *p1)//完成多项式相加运算,p=p+p1,并销毁p1 { Polyn *qa,*qb,*prior,*r;//设置prior是为B链表中的结点插入A链表用 prior = p; qa = p->next; qb = p1->next; while(qa && qb) { if(qa->index < qb->index) { prior = qa; qa = qa->next; } else if(qa->index > qb->index){ r = qb; qb = qb->next; //摘取qb到“和多项式”链表中 r->next = qa; prior->next = r; //更新prior prior = r; } else{ if(qa->data + qb->data != 0) { //修改qa所指结点的系数值,同时释放qb所指的结点 qa->data = qa->data + qb->data; r = qb; qb = qb->next; free(r); } else{ //释放指针qa和qb所指的结点 r = qa; qa = qa->next; prior->next = qa;//衔接 free(r); r = qb; qb = qb->next; free(r); } } } //B链表还有结点 if(qb) { prior->next = qb;//此时qa已为空指针 } free(p1);//释放B头结点 } void reverse(Polyn *p) { Polyn *q = p->next; while(q) { q->data = -(q->data); q = q->next; } } void DestroyPolyn(Polyn *r) { Polyn *q; do{ q = r; r = r->next; free(q); }while(r); } void AdjustPolyn(Polyn *r,int data,int index)//调整每一项 { Polyn *q = r->next; while(q) { q->data *= data; q->index += index; q = q->next; } } void SubtractPolyn(Polynlist &p,Polynlist &p1)//完成多项式相减运算,p=p-p1,并销毁p1 { reverse(p1);//将B链表的data域置反 AddPolyn(p,p1); } void MultiplyPolyn(Polynlist &p,Polyn *p1)//完成多项式相乘运算,p=p*p1,并销毁p1 { Polyn *q,*r = NULL,*r1 = NULL; q = p1->next; //A(x)--》bi*A(x)*x^ei CopyPolyn(r,p); AdjustPolyn(r,q->data,q->index); q = q->next; while(q) { CopyPolyn(r1,p); AdjustPolyn(r1,q->data,q->index); AddPolyn(r,r1);//r1将被销毁 r1 = NULL;//必须将r1置空 q = q->next; } //r-->p,同时释放r链表 DestroyPolyn(p); p = NULL; CopyPolyn(p,r); DestroyPolyn(r); } int main() { int m; Polyn *p=(Polyn*)malloc(sizeof(Polyn)); Polyn *p1=(Polyn*)malloc(sizeof(Polyn)); Polyn *p2 = NULL,*p3 = NULL; printf("按升幂输入多项式A(x),B(x)的系数,指数\n"); printf("A(x)的项数:"); scanf("%d",&m); CreatPolyn(p,m); printf("A(x)="); PrintPolyn(p); printf("B(x)的项数:"); scanf("%d",&m); CreatPolyn(p1,m); printf("B(x)="); PrintPolyn(p1); //保存A,B原始多项式,此处的复制是新开辟结点链表 CopyPolyn(p2,p); CopyPolyn(p3,p1); system("pause"); system("cls"); printf("A(x)="); PrintPolyn(p); printf("B(x)="); PrintPolyn(p1); printf("选择以下一种操作方式:\n"); ShowMenu(); do{ printf("请输入你的选择:"); scanf("%d",&m); switch(m) { case 1: AddPolyn(p,p1); printf("A(x)+B(x)="); PrintPolyn(p); break; case 2: SubtractPolyn(p,p1); printf("A(x)-B(x)="); PrintPolyn(p); break; case 3: MultiplyPolyn(p,p1); printf("A(x)*B(x)="); PrintPolyn(p); break; default: exit(0); } fflush(stdin); DestroyPolyn(p); p1 = p = NULL;//此时的p、p1为游离指针,必须要置空 CopyPolyn(p,p2); CopyPolyn(p1,p3); }while(1); return 0; }
运行结果截图:
按Enter键之后
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