C语言数据结构 一元多项式

#include
#include

struct Node {
double coef;
int expn;
Node *next;
};

void CreatPolynomial(Node *&head, int n) // 生成带表头结点的单链表，除头结点外另生成n个结点

{
int i;
head = (Node *)malloc(sizeof(Node));
head->coef = 0;
head->expn = 0;
head->next = NULL; // 初始化头结点

printf("请输入各项系数和指数：\n");
Node *p = head;
for (int i = 0; i < n; i++) {
p->next = (Node *)malloc(sizeof(Node)); // 生成新结点，尾插入生成链表

p = p->next;
scanf("%lf %d",&p->coef,&p->expn);
p->next = NULL;
}
}

void PrintPolynomial(Node *&head)
{
if (head->next == NULL) // 结果是0时直接输出0

putchar('0');
else {
for (Node *p = head->next; p != NULL; p = p->next) {
if (p != head->next && p->coef >0) // 当p非首项且指向的系数为正时才输出'+'

putchar('+'); // 之前只判定了p->coef >0

``````        if (p->coef == 1) {                       //  系数为1或-1时特殊处理
if (p->expn == 0)
putchar('1');                   //  判断条件不能写在一起：
}                                       //  if(p->coef == 1 && p->expn == 0) putchar('1');
else if (p->coef == -1)
putchar('-');
else
printf("%lf\n", p->coef);

switch (p->expn) {                        //  指数为0或1时特殊处理

case 0:
break;

case 1:
putchar('x');
break;

default:
p->expn < 0 ? printf("x^(%d)", p->expn) : printf("x^%d", p->expn);  //  指数小于0时打括号
break;
}
}
}
printf("\n");
``````

}

void Free(Node *&head)
{
Node *q = NULL;
for (Node *p = head; p != NULL; p = q) {
q = p->next;
free(p);
}
}

char cmp(int a, int b)
{
if (a > b)
return '>';
if (a < b)
return '<';
return '=';
}

void AddPolynomial(Node *&pA, Node *&pB) // 传进两个链表的头指针

{
Node *ha = pA;
Node *hb = pB;
Node *qa = ha->next; // ha, hb分别跟在qa, qb的后一位置

Node *qb = hb->next; // qa, qb分别指向Pa, Pb中当前比较元素

while (qa && qb)
{
double sum = 0;
int a = qa->expn;
int b = qb->expn;
switch (cmp(a, b)) {

``````    case '<':
ha = qa;
qa = qa->next;                       //  非ha = ha->next;
break;

case '=':
sum = qa->coef + qb->coef;
if (sum != 0.0) {
qa->coef = sum;
ha = qa;
}
else {
if (ha->next != qa)
printf("Error: ha->next != qa  \n");
ha->next = ha->next->next;     //  删除和为0的结点，ha不变，还在qa后一位置
free(qa);
}
if (hb->next != qb)
printf("Error: hb->next != qb  \n");
hb->next = hb->next->next;
free(qb);
qb = hb->next;
qa = ha->next;
break;

case '>':
hb->next = hb->next->next;         //  删除qb指向的结点
qb->next = ha->next;              //  将qb插入ha后qa前
ha->next = qb;

qb = hb->next;                       //  not qb = ha->next
ha = ha->next;
break;

default:
printf("Error!  \n");
break;
}
}
if (qb)
ha->next = qb;
free(hb);
``````

}

int main(void)
{

Node *A = NULL;
Node *B = NULL;
int lenA;
int lenB;
do
{
printf("请输入A的项数：\n");
scanf(" %d", &lenA);
CreatPolynomial(A, lenA); // 生成A链表

``````    printf("请输入B的项数：\n");//  生成B链表
scanf("%d\n",&lenB);
CreatPolynomial(B, lenB);

printf(" A= ");    //  输出A链表
PrintPolynomial(A);
printf(" B= ");//  输出B链表
PrintPolynomial(B);

AddPolynomial(A, B);                        //  A = A + B
printf(" A+B=  ");
PrintPolynomial(A);                         //  输出和
printf("\n");

Free(A);  //  释放结点
``````

} while (true);
return 0;
}