第1个回答 2011-12-09
编了两天，希望楼主打赏点财富值
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
struct polylink
{
char ch; /*变量名*/
float coef; /* 系数域*/
int expn; /* 指数域*/
struct polylink *next; /* 链域*/
};
/*初始化链表*/
polylink *initpoly()
{
polylink *p;
p = (polylink *)malloc(sizeof(polylink));
if(p == NULL)
{
printf("memory error!");
exit(0);
}
p->next = NULL;
return p;
}
/*销毁链表*/
void destroy_link(polylink *p)
{
polylink *q;
while(p != NULL)
{
q = p;
p = p->next;
free(q);
}
}
/*将多项式存入链表*/
polylink * creat_ploy(polylink *p)
{
char c[1];
int i = 0, n=0;
polylink *p1;
p = initpoly();
printf("input variable's name 输入变量名：\n");
scanf("%s", c);
printf("input the polynomial's number 输入多项式项数：\n");
scanf("%d", &n);
for(i = 0; i < n; i++)
{
p1 = (polylink *)malloc(sizeof(polylink));
if(p1 == NULL)/*分配不成功时*/
{
printf("memory error!");
exit(0);
}
printf("input the %dst's coefficient 输入第%d项的系数：\n", i+1, i+1);
scanf("%f", &p1->coef);
printf("input the variable's index 输入变量的指数：\n");
scanf("%d", &p1->expn);
p1->ch = c[0];
p1->next = p->next;
p->next = p1;
}
return p;
}
/*删除节点函数*/
polylink *delnode(polylink * h , polylink * maxp) /*删除一个节点，返回剩下的链表首地址*/
{
polylink *t;
t = h;
while(t->next != maxp )
t=t->next; /*找到maxp 的前节点t */
t->next = maxp->next ; /*删除maxp，maxp后面的接到t后面*/
maxp->next = NULL;
return h; /*链首依然是h ,返回 */
}
/*求表长函数*/
void link_lenth(polylink *p, int &a)/* &是引用*/
{
while(p->next != NULL)
{
p = p->next;
a++;
}
}
/*排序*/
polylink *sort(polylink *h)
{
int min; /*保存指数最小的值*/
polylink *t=NULL, *minp=NULL, *head=NULL;
if(h ->next == NULL)
{
printf("don't exist number");
exit(0);
}
while(h->next !=NULL) /*只要当前链中不为空就循环 */
{
t= h->next; // t ：临时指针
min=t->expn; minp=t; /*把当前t中的值作为最小*/
while (t->next !=NULL) /*只要t后面还有节点就循环*/
{
t=t->next ; /*t往后移动一个*/
if (t->expn < min) /*如果t中的值大于maxn，则记下其值和位置*/
{
min = t->expn;
minp=t;
}
} /*找出当前头开始在链中最大节点 maxp*/
h = delnode(h, minp); /*删除minp节点,返回剩下的链表*/
minp->next=head; /*将每次的最小节点接在头结点之前*/
head = minp; /*head 重新回到该链的开头*/
}
h->next = head; /*将head 接在头节点之后*/
return h;
}
/*对一元多项式求导*/
polylink *poly_derivation(polylink *p)
{
polylink *n, *q;
q= p;
if(p->next == NULL)
{
printf("polynomial don't exist!\n");
}
while(p->next != NULL)
{
p = p->next;
if(p->expn == 0 || p->coef == 0) /*指数为零或者系数为零就删除*/
{
q = delnode(q, p);
}
}
n = q; /*保存删除无用节点的链表之后的头结点， 用于返回*/
if(q->next == NULL)
{
printf("polynomial don't exist!\n");
}
while(q->next != NULL)
{
q = q->next;
q->coef = q->coef * q->expn; /*系数乘指数*/
q->expn = q->expn - 1; /*指数减一*/
}
return n;
}
/*显示多项式*/
void display_poly(polylink *p)
{
int a;
p = sort(p); /*排序*/
while(p->next != NULL )
{
p = p->next;
a = 1;
if(p->coef < 0) a = 0;
a ? printf(" +"): printf(" ");
printf("%.1f%c^%d", p->coef, p->ch, p->expn);
}
printf("\n");
}
/*查找函数*/
polylink *locate_link(polylink *p, int index)
{
p = p->next;
while(p != NULL && p->expn != index)
p = p->next;
if(p == NULL)
return NULL;
else
return p;
}
/*为了代码重用*/
void creat(polylink *&p1, polylink *&p2)
{
p1 = creat_ploy(p1); /*创建多项式*/
printf("another polynomial building:\n");
p2 = creat_ploy(p2); /*创建多项式*/
printf("first :\n");
display_poly(p1); /*显示创建的多项式*/
printf("the second:\n");
display_poly(p2); /*显示创建的多项式*/
}
/*多项式相加*/
polylink * poly_add(polylink *head1, polylink *head2, char a)
{
char ch[1];
polylink *p1, *p2, *p, *r;
p1 = head1;
p2 = head2;
if(a == '+') /*其他函数调用时不执行*/
{
system("cls");
creat(p1, p2); /*创建p1 p2*/
}
r = p1;
while(r->next != NULL)
{
p1 = r->next;
r = delnode(r, p1); /*删除p1*/
p = locate_link(p2, p1->expn); /*查找p2中是否有 系数等于p1->expn的节点，有就返回该点，否则返回NULL*/
if(p != NULL)
p->coef = p->coef + p1->coef;
else /*把节点p1插入到链表p2*/
{
p1->next = p2->next;
p2->next = p1;
}
}
if(a == '+') /*被减或者乘运算时不调用*/
{
printf("add result:\n");
display_poly(p2); /*显示*/
printf("whether to derivat:y/n\n");
scanf("%s", ch);
if( ch[0] == 'Y' || ch[0] == 'y')
{
p2 = poly_derivation(p2);
display_poly(p2);
destroy_link(p2); /*销毁链表*/
}
else
destroy_link(p2);/*销毁链表*/
getchar();/*让屏幕显示停在运算结果*/
return NULL;
}
return p2;
}
/*多项式相减*/
void poly_sub(polylink *p1, polylink *p2)
{
char ch[1];
polylink *n, *p;
system("cls"); /*清屏*/
creat(p1, p2);
p = p2;
while(p->next != NULL)
{
p = p->next;
p->coef = -1 * p->coef;
}
printf("\nsub 1st - 2st\n");
n = poly_add(p1, p2, '-'); /*调用加运算函数*/
display_poly(n);
printf("whether to derivat:y/n\n");
scanf("%s", ch);
if( ch[0] == 'Y' || ch[0] == 'y')
{
n = poly_derivation(n); /*求导*/
display_poly(n);
destroy_link(n);
}
else destroy_link(n);
getchar();
}
/*多项式相乘*/
polylink *multiply(polylink *p, float coef, int index)
{ /*传入系数和指数，分别与p的每个节点运算 最后返回该链*/
polylink *q, *n;
n = (polylink *)malloc(sizeof(polylink));
n->next = NULL; /*n作为头节点*/
while(p->next != NULL)
{
p = p->next;
q = (polylink *)malloc(sizeof(polylink));
q->ch = p->ch;
q->coef = coef * p->coef;
q->expn = index + p->expn;
q->next = n->next;
n->next = q;
}
return n;
}
/*多项式相乘所用，另外为了提高代码重用性*/
void run_mul(polylink *p1, polylink *p2, int num)
{
int i = 0;
char ch[1];
polylink **p, *q; /*二维指针存每次multiply（）函数返回的链表*/
p = (polylink **)malloc( num *sizeof(polylink));
while(p1->next != NULL)
{
p1 = p1->next;
p[i++] = multiply(p2, p1->coef, p1->expn);
}
q = poly_add(p[0], p[1], '*');
for(i = 2; i < num; i++)
{
q = poly_add(q, p[i], '*');
}
printf("mul result:\n");
display_poly(q);
printf("whether to derivat:y/n\n");
scanf("%s", ch);
if( ch[0] == 'Y' || ch[0] == 'y')
{
q = poly_derivation(q);
display_poly(q);
destroy_link(q);
}
else destroy_link(q);
getchar();
}
void poly_mul(polylink *p1, polylink *p2)
{
int num1 =0 , num2 = 0; /*用于存放p1 ，p2的表长*/
system("cls");
creat(p1, p2);
link_lenth(p1, num1);
link_lenth(p2, num2);
if(num2 >= num1) /*根据链表*/
{
run_mul(p1, p2, num1);
}
else
{
run_mul(p2, p1, num2);
}
}
/*选择函数*/
int menu_select()
{
int n;
printf("press enter key to enter the menu......"); /*按任一键进入主菜单*/
getchar(); /*从键盘读取一个字符,但不显示于屏幕*/
system("cls"); /*清屏*/
printf("\n\n\n\n\n\n");
printf("\t\t\tIt just for a variables\n\n");
printf("\t*************************************MENU***********************\n\n");
printf("\t\t\t1. 多项式相加 add operation\n\n");
printf("\t\t\t2. 多项式相减 sub operation\n\n"); /*显示*/
printf("\t\t\t3. 多项式相乘 mul operation\n\n"); /*寻找*/
printf("\t\t\t4. 退出 Quit\n\n"); /*删除*/
printf("\t****************************************************************\n\n");
do{
printf("\n\t输入你的选择Enter your choice(1~4):");
scanf("%d",&n);
}while(n < 1 || n > 4); /*如果选择项不在1~4之间则重输*/
return n; /*返回选择项，主函数根据该数调用相应的函数*/
}
void main()
{
polylink *head1=NULL, *head2=NULL, *head3=NULL; /*head3的作用不是很大*/
for(;;) /*循环无限次*/
{
switch( menu_select() )
{
case 1: head3 = poly_add(head1, head2, '+'); break;
case 2: poly_sub(head1, head2); break;
case 3: poly_mul(head1, head2); break;
case 4: exit(0); /*如菜单返回值为4则程序结束*/
}
}
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