shuffle.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 84 行

/* Demo of my guess of Mplayer's -shuffle argv.
 *
 * Written by Cyril Hu ([e-mail]), public domain.
 */
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<time.h>
#define MAX 80
#define N 10
typedef struct plink {
	char *data;
	struct plink *next;
} PL;

PL *head, *t;

void destroy(PL *p)
{
	PL *t;
	while(p) {
		p = p->next;
		free(p);
		free(p->data);
		p = t;
	}
}
void disp(PL *p)
{
	puts("");
	while(p) {
		printf("%s", p->data);
		p = p->next;
	}
}
PL *mvlink(PL *p, size_t n)
{
	size_t i;
	for(i=1; i<n && p; i++,p=p->next);
	return p;
}
void swap(PL *a, PL *b)
{
	char *t = a->data; a->data = b->data; b->data = t;
}
void add_to_link(const char *src, size_t len, size_t cnt)
{
	PL *p;
	char *dst;
	p = (PL *)malloc(sizeof(PL));
        dst = (char *)calloc(len, sizeof(char));
	if(!p || !dst) {
		fprintf(stderr, "Fatal: mem alloc failed");
		exit(EXIT_FAILURE);
	}
	strcpy(dst, src);
	p->data = dst;
	if(cnt == 1) 
		head = t = p;
	else {
		t->next = p;
		t = p;
	}
	t->next = NULL;
}

int main(void)
{
	char buf[MAX];
	size_t i, j, cnt = 0;
	for(i=0; i<N; ++i) {
		fgets(buf, sizeof(buf), stdin);
		add_to_link(buf, strlen(buf), ++cnt);
	}
	srand(time(NULL));
	for(i=1; i<=cnt; i++) {
		j = 1 + (size_t )( (double)cnt * rand() / ( (RAND_MAX) + 1.0));
		swap(mvlink(head, i), mvlink(head, j));
	}
	disp(head);
	destroy(head);
	return EXIT_SUCCESS;
}