polynomial.c

自己做的常用库和实现的数据结构。public domain.

/* Demo of polynomial expression, using dynamic link data structure.
 *
 * Written by Cyril Hu ([e-mail]), public domain.
 */
#include "my.h"

typedef struct pn {
	int coef;
	int pow;
	struct pn *next;
} PN;

PN *initln(size_t n)
{
	size_t i;
	PN *t, *head, *p;
	for(i=0; i<n; i++) {
		p = mem('m', sizeof(PN));
		do {
			puts("Input coeffienct( coeffienct != 0 ) & power(one bye one, in descending order)");
			scanf("%d%d", &p->coef, &p->pow);
		} while(p->coef == 0);
		i ? t->next = p : (head = p);
		t = p;
	}
	p->next = NULL;
	return head;
}

void pntln(PN *head)
{
	int i;
	printf("PolyNomial Expression = ");
	while(head != NULL) {
		printf("%d*", head->coef);
		for(i=0; i < head->pow; i++) 
			printf("x*");
		printf("\b + ");
		head = head->next;
	}
	printf("\b\b \n");
}
int compar(PN *p1, PN *p2)
{
	return p1->pow - p2->pow;
}
void merge(PN *dst, PN **p2)
{
	PN *t;
	dst->coef += (*p2)->coef;
	t = (*p2)->next;
	free(*p2);
	*p2 = t;
}
void cmpln(PN *head, PN *p2)
{
	int cmp;
	PN *p1;
	if( !(p1 = head->next) || ! p2) {
		head->next = p2;
		return;
	}
	if( (cmp = compar(p1, p2)) == 0) {
		merge(p1, &p2);
		cmpln(head, p2);
	} else if(cmp>0)
		cmpln(p1, p2);
	else {
		head->next = p2;
		cmpln(p2, p1);
	}
}
PN *addln(PN *p1, PN *p2)
{
	int cmp = compar(p1, p2);
	PN *head = NULL;
	if(! p1 && p2)
		return p2;
	if(p1 && ! p2)
		return p1;
	if(p1 && p2) {
		if(cmp >= 0) {
			if(cmp==0)
				merge(p1, &p2);
			cmpln(head=p1, p2);
		} else 
			cmpln(head=p2, p1);
	}
	return head;
}

int main(void)
{
	size_t m,n;
	PN *p1, *p2;

	puts("How many nodes to create?");
	scanf("%d", &m);
	p1 = initln(m);
	pntln(p1);

	puts("How many nodes to create?");
	scanf("%d", &n);
	p2 = initln(n);
	pntln(p2);

	p1 = addln(p1, p2);
	puts("\nAfter adding 2 polynomial expression together,");
	pntln(p1);
	return 0;
}