单链表的基本操作

今天我们来看看单链表的基本操作：初始化，插入（头插、尾插），查找，删除，判空，求长，摧毁，逆置。

.cpp:

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "list.h"

void InitList(List plist)
{
	assert(plist != NULL);

	plist->next = NULL;
	//plist->data不用操作
}

//头插
bool Insert_Head(List plist,int val)
{
	Node *p = (Node *)malloc(sizeof(Node));
	p->data = val;
	p->next = plist->next;
	plist->next = p;
	return true;
}

//尾插
bool Insert_Tail(List plist,int val)
{
	Node *p = (Node *)malloc(sizeof(Node));
	p->data = val;

	Node *q;
	for(q=plist;q->next!=NULL;q=q->next) ;

	//将p插入在q的后面
	p->next = q->next;//p->next = NULL;
	q->next = p;

	return true;
}

Node *Search(List plist,int key)
{
	for(Node *p=plist->next;p!=NULL;p=p->next)
	{
		if(p->data == key)
		{
			return p;
		}
	}

	return NULL;
}

//查找key的前驱
static Node *SearchPri(List plist,int key)
{
	for(Node *p=plist;p->next!=NULL;p=p->next)
	{
		if(p->next->data == key)
		{
			return p;
		}
	}
	return NULL;
}

bool Delete(List plist,int key)
{
	Node *p = SearchPri(plist,key);
	if(p == NULL)
	{
		return false;
	}

	Node *q = p->next;
	p->next = q->next;//将q从链表中剔除
	//p->next = p->next->next;
	free(q);

	return true;
}

bool IsEmpty(List plist)
{
	return plist->next == NULL;
}

int GetLength(List plist)
{
	int count = 0;
	for(Node *p=plist->next;p!=NULL;p=p->next)
	{
		count++;
	}
	return count;
}

void Show(List plist)
{
	for(Node *p=plist->next;p!=NULL;p=p->next)
	{
		printf("%d ",p->data);
	}
	printf("\n");
}

void Clear(List plist)
{
	Destroy(plist);
}

void Destroy(List plist)
{
	Node *p;
	while(plist->next != NULL)//第一种方法总删除第一个数据节点
	{
		p = plist->next;
		plist->next = p->next;
		free(p);
	}
	/*
	Node *p = plist->next;//第二种方法
	//Node *q = p->next;//bug
	Node *q;
	while(p != NULL)
	{
		q = p->next;
		free(p);
		p = q;
	}

	plist->next = NULL;
	*/
}

void Revers(List plist)//逆置
{
	//第一种方法头插的思想
	if(plist==NULL || plist->next==NULL ||
	   plist->next->next==NULL)
	{
		return ;
	}
	Node *p = plist->next;
	Node *q;
	plist->next = NULL;//

	while(p != NULL)
	{
		q = p->next;
		//将p头插进链表
		p->next = plist->next;
		plist->next = p;
		p = q;
	}
//第二种方法	
#if 0
	/*if(plist->next->next==NULL ||
	   plist==NULL || plist->next==NULL 
	   )*///error
	if(plist==NULL || plist->next==NULL ||
	   plist->next->next==NULL)
	{
		return ;
	}
	Node*p = plist->next;
	Node *q = p->next;
	Node *s;
	p->next = NULL;

	while(q != NULL)
	{
		s = q->next;
		q->next = p;
		p = q;
		q = s;
	}

	plist->next = p;
#endif
}

.h:

#pragma once
//带头节点的单链表

typedef struct Node
{
	int data;//数据域
	struct Node *next;//指向下一个节点
}Node,*List;//List == Node*

void InitList(List plist);//Node *plist

//头插
bool Insert_Head(List plist,int val);

//尾插
bool Insert_Tail(List plist,int val);

Node *Search(List plist,int key);//List 
Node *Search_before(List plist,int key);

bool Delete(List plist,int key);

bool IsEmpty(List plist);

int GetLength(List plist);

void Show(List plist);

void Clear(List plist);

void Destroy(List plist);

void Revers(List plist);