链表

一、单链表（带头结点的）

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

typedef struct node
{ 
int data;
struct node * next;
}node,*pnode;


pnode initialize();//单链表初始化


int isempty(struct node *);

//int isfull();链表只要内存有空间就不会满

void dlb_insert(int x,struct node *);


pnode dlb_search(int x,struct node *);


void dlb_delete(int x, node *proot);


void dlb_print(struct node*);//打印单链表的节点

int  main()
{
pnode root=initialize();
dlb_insert(8,root);
dlb_insert(5,root);
dlb_insert(4,root);
dlb_insert(2,root);
dlb_insert(1,root);
dlb_print(root);
printf("-------------------\n");
printf("look up element:%d\n",dlb_search(5,root)->data);
printf("-------------------\n");
dlb_delete(10,root);
dlb_print(root);
//printf("%d\n",root->next->data);
printf("-------------------\n");
dlb_delete(5,root);
dlb_print(root);
return 0;
}


pnode initialize()
{
pnode proot;
proot=(pnode)malloc(sizeof(struct node));//若要给proot赋值，就需要为其分配内存空间
if(proot==NULL){
perror("initialize faiture!\n");
exit(-1);
}
//proot->data=0;//可以定义头结点的data的意义，比如所有节点的个数什么的
proot->next=NULL;


return proot;
}


int isempty(pnode root)
{
return root->next==NULL?1:0 ;
}


void dlb_insert(int x,struct node * proot)
{
struct node * pre=proot;
struct node * cur=proot->next;
struct node * newn;
while(cur!=NULL&&cur->data<x){
pre=cur;
cur=cur->next;

}
newn=(pnode)malloc(sizeof(struct node));


if(newn==NULL){
perror("malloc faiture!\n");
exit(-1);}


newn->data=x;
newn->next=cur;
pre->next=newn;




}
pnode dlb_search(int x,struct node *proot){
struct node *cur=proot->next;
while(cur!=NULL)
{
if(cur->data==x)
break;
else
cur=cur->next;
}


return cur;
}


void dlb_delete(int x, node *proot)
{
struct node *pre=proot;
struct node *cur=proot->next;

while(cur!=NULL&&cur->data!=x){
pre=cur;
cur=cur->next;
}


if(cur==NULL){
printf("%d not in proot\n",x);
}else{
pre->next=cur->next;
free(cur);
}
return ;
}


void dlb_print(struct node* proot)
{
pnode cur=proot->next;
while(cur!=NULL){
printf("%d%c",cur->data,cur->next==NULL?'\n':' ');
cur=cur->next;
}
return ;

}

二、双链表

该双链表是带头结点的，头结点的next指针指向双链表的第一个节点，头结点的prev指针指向双链表的最后一个节点。

同时第一个节点的prev为空，最后一个节点的next为空。

主要就插入和删除两个函数。

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

typedef struct node{
int data;
struct node* next;
struct node* prev;
}node,*pnode;


pnode initialize();//双链表初始化


void slb_insert(int x,struct node *proot);


void slb_delete(int x,struct node *proot);


pnode slb_search(int x,struct node *proot);


void slb_print(struct node *proot);

int isempty(struct node *proot);

int main()
{
pnode root=initialize();
slb_insert(7,root);
slb_insert(9,root);
slb_insert(5,root);
slb_insert(3,root);
slb_insert(1,root);
printf("the number of element:%d\n",root->data);
slb_print(root);
printf("-----------------\n");
printf("look up element:%d\n",slb_search(5,root)->data);
printf("-----------------\n");
slb_delete(11,root);
slb_delete(5,root);
slb_print(root);
printf("the number of elements:%d\n",root->data);
return 0;
}

int isempty(struct node *proot)
{
if(proot->next==NULL&&proot->prev==NULL)
return 1;
else
return 0;
}

pnode initialize()
{
pnode root;
root=(pnode)malloc(sizeof(struct node));
if(root==NULL){
printf("malloc failture\n");
return root;
}
root->next=NULL;
root->prev=NULL;
root->data=0;//头结点中的data用于记录双链表中节点的个数

return root;

}

/*双链表的插入分四种情况：中间、头、尾、头&&尾
*/
void slb_insert(int x,struct node* proot)
{
struct node * fro;
struct node * cur;
struct node * newd;


fro=proot;
cur=proot->next;
while(cur!=NULL&&cur->data<x)
{
fro=cur;
cur=cur->next;
}


newd=(pnode)malloc(sizeof(struct node));
if(newd==NULL){
perror("malloc failture\n");
return ;
}
newd->data=x;
if(cur!=NULL){
if(fro!=proot){//中间
newd->next=cur;
newd->prev=fro;
cur->prev=newd;
fro->next=newd;
}
else{//头部
newd->next=cur;
newd->prev=NULL;
cur->prev=newd;
fro->next=newd;
}
}
else{//尾部
if(fro!=proot){
newd->next=cur;
fro->next=newd;
newd->prev=fro;
proot->prev=newd;
}
else{//头&&尾
newd->next=cur;
newd->prev=fro;
fro->next=newd;
fro->prev=newd;
}
}

proot->data++;

}


void slb_print(struct node *proot)
{
if(!isempty(proot)){
struct node *cur=proot->next;
while(cur!=NULL){
//printf("not null\n");
printf("%d %c",cur->data,cur->next==NULL?'\n':' ');
cur=cur->next;
}
}
}


pnode slb_search(int x,struct node *proot)
{
if(!isempty(proot)){
struct node * cur;
cur=proot->next;
while(cur!=NULL&&cur->data!=x)
cur=cur->next;


return cur;}
}


void slb_delete(int x,struct node *proot)
{
if(!isempty(proot)){
struct node * fro=proot;
struct node * cur=proot->next;
while(cur!=NULL&&cur->data!=x){
fro=cur;
cur=cur->next;
}


if(cur==NULL){
printf("%d not in slb\n",x);
return ;
}
if(cur->next!=NULL){
if(fro!=proot){
fro->next=cur->next;
cur->next->prev=fro;
}
else{
fro->next=cur->next;
cur->next->prev=NULL;
}
}
else{
if(fro!=proot){
cur->prev->next=NULL;
proot->prev=cur->prev;
}
else{
proot->next=NULL;
proot->prev=NULL;
}
}


proot->data--;




}
}