十四、数据结构之链表

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

//数据类型
typedef int ElemType;
//节点存储结构, 头结点用来存储长度
typedef struct Node
{
	ElemType data;
	struct Node *next;		
}Node;

typedef Node *PtrToNode;
//节点指针
typedef PtrToNode Position;
//链表
typedef PtrToNode List;

//链表初始化，对头结点进行初始化，数据域存储链表长度
void Init(List *l)
{
     (*l) = (Position)malloc(sizeof(Node));
     if((*l) == NULL) exit(0); 
	 (*l) -> next = NULL;
	 (*l) -> data = 0;  
}

//链表是否为空
int IsEmpty(List l)
{
	return l -> next == NULL;
}

//节点是否拥有下一个元素
int IsLast(Position p)
{
	return p -> next == NULL;
} 

//获取链表长度
int Length(List l)
{
	return l -> data;
}

//查找节点
Position Find(ElemType data, List l)
{
	Position p = l -> next;
	while(p != NULL && p -> data != data)
	{
		p = p -> next;
	}
	return p;
}

//查找前一个节点
Position FindPrevious(ElemType data, List l)
{
	Position p = l;
	while(p -> next != NULL && p -> next -> data != data)
	{
		p = l -> next;
	}
	return p;
}

//查找最后一个节点
Position FindLast(List l)
{
	Position p = l;
	while(p -> next != NULL)
	{
		p = p -> next;
	}
	return p;
}


//添加
Position Add(ElemType data, List l)
{
	Position p = (Position)malloc(sizeof(Node));
	if(p == NULL) exit(0);
	p -> data = data;
	p -> next = NULL;
	Position lastP = FindLast(l);
	lastP -> next = p;
	l -> data++;
	return p;
}

//执行插入
void Insert(ElemType data, List l, Position p)
{
	Position tempCell = (Position)malloc(sizeof(Node));
	if(tempCell == NULL) exit(0);
	tempCell -> data = data;
	tempCell -> next = p -> next;
	p -> next = tempCell;
	l -> data++;
}

//执行删除
void Delete(List l, Position p)
{
	if(p == NULL) return;	
	Position tmpCell = p -> next;
	p -> next = tmpCell -> next;
	free(tmpCell);
	l -> data--;
}

//清空链表
void Empty(List l)
{
	Position p = l -> next;
	Position f;
	while(p != NULL)
	{
		f = p -> next;
		free(p);
		p = f;
		l -> data--;
	}
	l -> next = NULL;
}

int main(void)
{
	List l;
	Init(&l);
	Position p = Add(3, l);
	printf("%d, %d\n", Length(l), p -> data);
	Position p2 = FindPrevious(3, l);
	Insert(2, l, p2);
	//Position p3 = Find(2, l);
	Position p4 = FindLast(l);
	printf("%d, %d\n", Length(l), p4 -> data);
	Delete(l, p2);
	printf("%d, %d\n", Length(l), l -> next -> data);
	Empty(l);
	printf("%d, %d\n", Length(l), l -> data);
	return 0;
}