模拟双链表简单操作.

[_谦言万语]

#include <stdio.h>
#include <malloc.h>

typedef struct DNode
{
	char data;
	struct DNode *prior;
	struct DNode *next;
}DLinkNode;

void CreateListF(DLinkNode *&L, char a[], int n)
{
	DLinkNode *s;
	L=(DLinkNode *)malloc(sizeof(DLinkNode));
	L->prior=L->next=NULL;
	for(int i=0; i<n; i++)
	{
		s=(DLinkNode *)malloc(sizeof(DLinkNode));
		s->data=a[i];
		s->next=L->next;
		if(L->next!=NULL) L->next->prior=s;
		s->prior=L;
		L->next=s;
	}
}

void CreateListR(DLinkNode *&L, char a[], int n)
{
	DLinkNode *s,*r;
	L=(DLinkNode *)malloc(sizeof(DLinkNode));
	L->prior=L->next=NULL;
	r=L;
	for(int i=0; i<n; i++)
	{
		s=(DLinkNode *)malloc(sizeof(DLinkNode));
		s->data=a[i];
		r->next=s;
		s->prior=r;
		r=s; //往后挪一位 
	}
	r->next=NULL; 
} 

void InitList(DLinkNode *&L)
{
	L=(DLinkNode *)malloc(sizeof(DLinkNode));
	L->prior=L->next=NULL;
}

void DestroyList(DLinkNode *&L)
{
	DLinkNode *pre=L, *p=L->next;
	while(p!=NULL)
	{
		free(pre);
		pre=p;
		p=p->next;
	}
	free(pre);
}
bool ListEmpty(DLinkNode *L)
{
	return (L->next==NULL);
} 

int ListLength(DLinkNode *L)
{
	DLinkNode *p=L;
	int i=0;
	while(p->next!=NULL)
	{
		i++;
		p=p->next;
	}
	return i;
}

void DispList(DLinkNode *L)
{
	DLinkNode *p=L->next;
	while(p!=NULL)
	{
		printf("%c ",p->data);
		p=p->next;
	}
	printf("\n");
}

bool ListInsert(DLinkNode *&L, int i, char e)
{
	int j=0;
	DLinkNode *p=L, *s;
	if(i<=0) return false;
	while(j<i-1 && p!=NULL)
	{
		j++;
		p=p->next;
	}
	if(p==NULL) return false;
	else 
	{
		s=(DLinkNode *)malloc(sizeof(DLinkNode));
		s->data=e;
		s->next=p->next;
		if(p->next!=NULL) p->next->prior=s;
		s->prior=p;
		p->next=s;
		return true;
	}
}

//删除的是q指向的结点 
bool ListDelete(DLinkNode *&L,int i)
{
	int j=0;
	DLinkNode *p=L,*q;
	if(i<=0) return false;
	while(j<i-1 && p!=NULL)
	{
		j++;
		p=p->next;
	}
	if(p==NULL) return false;
	else
	{
		q=p->next;
		if(q==NULL) return false;
		p->next=q->next;
		if(q->next!=NULL)
			q->next->prior=p; 
		free(q);
		return true;
	}
}

bool GetElem(DLinkNode *L,int i,char &e)
{
	int j=0;
	DLinkNode *p=L;
	if(i<=0) return false;
	while(j<i && p!=NULL)
	{
		j++;
		p=p->next;
	}
	if(p==NULL) return false;
	else
	{
		e=p->data;
		return true;
	}
}

int LocateElem(DLinkNode *L,char e)
{
	int i=1;
	DLinkNode *p=L->next;
	while(p!=NULL && p->data!=e)
	{
		i++;
		p=p->next;
	}
	if(p==NULL) return 0;
	else return i;
}

int main()
{
	DLinkNode *h;
	char e;
	printf("双链表的基本运算如下：\n");
	printf("  (1)初始化双链表h\n");
	InitList(h);
	printf("  (2)依次采用尾插法插入a,b,c,d,e元素\n");
	ListInsert(h,1,'a'); 
	ListInsert(h,2,'b');
	ListInsert(h,3,'c');
	ListInsert(h,4,'d');
	ListInsert(h,5,'e');
	printf("  (3)输出双链表h:"); DispList(h);
	printf("  (4)双链表h的长度：%d\n",ListLength(h));
	printf("  (5)双链表h为%s\n",(ListEmpty(h) ? "空" : "非空"));
	GetElem(h,3,e);
	printf("  (6)双链表h的第3个元素:%c\n",e);
	printf("  (7)元素a的位置：%d\n",LocateElem(h,'a'));
	printf("  (8)在第4个元素位置上插入f元素\n");
	ListInsert(h,4,'f'); 
	printf("  (9)输出双链表h:"); DispList(h);
	printf("  (10)删除h的第3个元素\n");
	ListDelete(h,3);
	printf("  (11)输出双链表h:"); DispList(h);
	printf("  (12)释放双链表h\n");
	DestroyList(h);
	return 0;
}