doublelink.c

来自「自己做的常用库和实现的数据结构。public domain.」· C语言 代码 · 共 103 行

/* Demo of simple double link manipulation.
 *
 * Written by Cyril Hu ([e-mail]), public domain.
 */

#include<stdio.h>
#include<stdlib.h>

#define MAX_LEN 10
#define MEM(X) if( ((X)=(A *)malloc(sizeof(A))) == NULL) { \
			fprintf(stderr, "Fatal: MEM alloc fail"); \
			exit(EXIT_FAILURE); \
		}

typedef struct a {
	int sn;
	struct a *prev;
	struct a *next;
} A;

static A *rev(A *head, int n)
{
	A *t, *p;
	int i,j;
	for(p=head,i=0; i < n/2; i++,p = p->next) {
		for(j=1,t=head; j < n-i; j++) {
			t = t->next;
		}
		j = p->sn; p->sn = t->sn; t->sn = j;
	}
	return head;
}

int main(void)
{
	A a, *head, *tail, *t, *p;
	int i;

	for(p=&a,i=0; i<MAX_LEN; i++) {
		MEM(p->next)
		p = p->next;
		p->sn = i;
	}
	p->next = NULL;

	puts("original link");
	for(p=a.next; p != NULL; p = p->next) {
		printf("%d ", p->sn);
	}

	puts("\nlink reversed");
	head = rev(a.next, MAX_LEN);
	for(p=head; p != NULL; p = p->next) {
		printf("%d ", p->sn);
	}

	puts("\nreversed again");
	head = rev(head, MAX_LEN);
	for(p=head; p != NULL; p = p->next) {
		printf("%d ", p->sn);
	}

	for(i=0; i<MAX_LEN; i++) {
		MEM(p)
		p->sn = i+10;
		if(i == 0) {
			head = t = p;
			p->prev = NULL;
		} else {
			t->next = p;
			p->prev = t; 
			t = p;
		}
	}
	tail = p;
	p->next = NULL;

	puts("\n\nprint new original link from head to tail");
	for(p=head; p != NULL; p = p->next) {
		printf("%d ", p->sn);
	}

	puts("\nprint from tail to head");
	for(p=tail; p != NULL; p = p->prev) {
		printf("%d ", p->sn);
	}

	puts("\nlink reversed, print from head to tail");
	head = rev(head, MAX_LEN);
	for(p=head; p != NULL; p = p->next) {
		printf("%d ", p->sn);
	}

	puts("\nreversed again, print from tail to head");
	head = rev(head, MAX_LEN);
	for(p=tail; p != NULL; p = p->prev) {
		printf("%d ", p->sn);
	}
	puts("");

	return EXIT_SUCCESS;
}