#define YES 1
#define NO 0
typedef int elemtype;
typedef struct node
{
elemtype data;
struct node *next;
struct node *prior;
}*dlink;

改：
#ifndef _MYDEFINEFILE_H
#define _MYDEFINEFILE_H

#define YES 1
#define NO 0
typedef int elemtype;
typedef struct node
{
elemtype data;
struct node *next;
struct node *prior;
}*dlink;

#endif