Doubly linked
single linked list in each node stores its own data after removal, also stored address of the next node, the next node is therefore an easy access to, and behind the successor node, but if you want to access the preceding node No, I can't go back anymore. For example, when deleting a node p, the previous node q must be found first, and then the p node can be deleted. The singly linked list can only go backwards, not forwards. What if you need to move forward?
At this time we need the doubly linked list to appear. The doubly linked list adds a pointer to the previous element on the basis of the single-
necklace list. It is in the form of typedef int Elemdata;
typedef struct _DoubleList{ Elemdata data; //Here Elemdata is custom The int element type _DoubleList *next; _DoubleList *prev;
}DoubleList,Node;
/*
Doubly-linked list
1, doubly-linked list initialization
2, doubly-linked
list before insertion method 3, doubly-linked list after insertion method
4, doubly-linked list insertion at any position
5, doubly-linked list delete element
6, doubly-linked list get element
7, two-way The linked list determines whether the element exists.
8, the traversal
of the doubly linked list, the destruction of the doubly linked list. The
so-called doubly linked list is undoubtedly the addition of a prev pointer based on a single necklace list.
*/
On code
#include<stdio.h>
#include<iostream>
#include<Windows.h>
#include<iostream>
using namespace std;
typedef int Elemdata;
typedef struct _DoubleList{
Elemdata data;
_DoubleList *next;
_DoubleList *prev;
}DoubleList,Node;
//1、双向链表初始化
bool initDoubleList(DoubleList *&L){
L= new DoubleList;
if(!L) return false;
L->next=NULL;
L->prev=NULL;
return true;
}
//2、双向链表的后插法
bool insert_end(DoubleList *&L,Node *node){
if(!L||!node) return false;
//查找最后一个结点
Node *p=L;
while(p->next){
p=p->next;
}
//找到最后一个结点后p
node->next = NULL;
node->prev = p;
p->next= node;
return true;
}
//3、双向链表的前面插入法则
bool insert_front(DoubleList *&L,Node *node){
if(!L||!node)return false;
//前插法则要判断前面的那个元素后面有没有元素
Node * p = L;
if(!L->next){
//如果仅有一个头节点,就先当与尾插法
node->next= p->next;//也可以写成node-next =NULL;
node->prev = p;
p->next = node;
}else{
//否则
node->next = p->next;
p->next->prev = node;
node->prev=p;
p->next=node;
}
return true;
}
//4、双向链表的任意位置插入
bool insertPos(DoubleList *&L,int i,Elemdata &e){
if(!L||i<1) return false;
//找到要插入的位置，必须是插入，尾部插入我们在这里不算必须要是在两个元素的中间插入
Node *p = L;
int j=0;
while(p&&j<i){
p=p->next;
j++;
}
//插入位置的next结点必须存在元素
if(!p||j!=i)return false;
Node *s = new Node;
s->data = e;
p->prev->next = s;
s->prev = p->prev;
s->next = p;
p->prev =s;
return true;
}
//5、双向链表删除指定位置的元素
bool deleteElem(DoubleList *&L,int i){
if(!L) return false;
int j=0;
Node *p,*d;
p = L;
//找到该位置的元素
while(j<i&&p){
p = p->next;
j++;
}
if(!p||j!=i) return false;
//判断该位置的下一个结点是否存在
if(p->next){
//下一个结点存在元素
d = p;
p->prev->next = p->next;
p->next->prev = p->prev;
}else{
//下一结点不存在
d = p;
p->prev->next = p->next;
delete d;
}
return true;
}
//获取元素
bool getElemdata(DoubleList *&L,int i,Elemdata &e){
//获取位置为i的元素
if(!L)return false;
DoubleList *p = L;
int j =0;
while(j<i&&p){
p=p->next;
j++;
}
if(!p||i!=j) return false;
e = p->data;
return true;
}
//判断元素是否存在
bool isExitElemdata(DoubleList *&L,Elemdata &e){
if(!L) return false;
Node *p=L->next;
while(p&&p->data!=e){
p = p->next;
}
if(!p)
return false; //如果是到p=NULL结束循环直接返回
else
return true;
//否则 得到元素
}
//双向链表的遍历
void printList(DoubleList *&L){
if(!L)return ;
DoubleList *p = L->next;
printf("顺序法遍历:");
while(p){
printf("%d\t",p->data);
p=p->next;
}
printf("\n");
DoubleList *last =L;
while(last->next){
last = last->next;
}
//找到最后一个节点后
printf("逆序遍历:");
while(last->prev){
printf("%d\t",last->data);
last=last->prev;
}
printf("\n");
}
void destoyed(DoubleList *&L){
if(!L) return ;
Node *p,*d;
p=L;
while(p){
d = p;
p=p->next;
delete d;
}
L = NULL;
}
//测试代码
int main(void){
DoubleList *L = NULL;
Node *s;
if(initDoubleList(L)){
printf("链表初始化成功！\n");
}else{
printf("链表初始化失败!\n");
}
cout<<"请输入5个元素:"<<endl;
for(int i=0;i<5;i++){
s = new Node;
cin>>s->data;
insert_end(L,s);
}
printList(L);
int x=5;
if(insertPos(L,1,x)){
cout<<"元素"<<x<<"插入成功！"<<endl;
}else{
cout<<"元素"<<x<<"插入失败！"<<endl;
}
printList(L);
int e=22;
if(isExitElemdata(L,e)){
cout<<"元素"<<e<<"存在"<<endl;
}else{
cout<<"元素"<<e<<"不存在"<<endl;
}
//获取元素
if(getElemdata(L,1,e)){
cout<<"成功获取元素"<<e<<endl;
}else{
cout<<"失败获取元素"<<e<<endl;
}
//销毁链表
destoyed(L);
if(initDoubleList(L)){
printf("链表初始化成功！\n");
}else{
printf("链表初始化失败!\n");
}
for(int i=0;i<5;i++){
s = new Node;
cin>>s->data;
insert_end(L,s);
}
system("pause");
return 0;
}
The difficulty of the double chain in the data structure algorithm is considered to take more time to understand.