在数据结构中，链接列表是数据元素的线性集合。列表中的每个元素或节点都包含两项-数据和对下一个节点的引用。最后一个节点具有对null的引用。在链接列表中，入口点称为列表的开头。
在“循环双链表”中，两个连续元素通过上一个和下一个指针链接或连接，最后一个节点通过下一个指针指向第一个节点，第一个节点也通过前一个指针指向最后一个节点。
Begin We shall create a class circulardoublylist which have the following functions: nod *create_node(int) = To memory allocated for node dynamically. insert_begin() = To Insert elements at beginning of the list. A) If the list is empty, then insert the node and set next and previous pointer as NULL. B) If the list is not empty, insert the data and set next and previous pointer and update them. insert_end() = To Insert elements at end of the list: A) If the list is empty create a node as circular doubly list. B) Find last node. C) Create node dynamically. D) Start going to be the next of new node. E) Make new node as previous node. F) Make last previous of new node. G) Make new node next of old last. insert_pos() = To insert elements at a specified position of the list: A) Insert the data. B) Enter the position at which element to be inserted. C) If the list is empty insert node at first. D) If list is not empty find node having position and next node. E) Insert the node between them. delete_pos() = To delete elements from specified position of the list: A) If list is empty, then return. B) Enter the position from which node needs to be deleted. C) If list has one node delete it and update next and prev pointers. D) If list has more than one nodes, then delete the node at particular position and update next and prev pointer. search() = To search element in the list: A) If the list is empty, then return. B) Enter the value to be searched. C) Print the position at which element to be found. D) If the element is not found, print not found. update() = To update value at a particular node: A) If the list is empty, then return. B) Enter the position of node to be updated. C) Enter the new value. D) Update the node. display() = To display the list. reverse() = To reverse the list. End
#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;
struct nod {
int info;
struct nod *n;
struct nod *p;
}*start, *last;
int count = 0;
class circulardoublylist {
public:
nod *create_node(int);
void insert_begin();
void insert_end();
void insert_pos();
void delete_pos();
void search();
void update();
void display();
void reverse();
circulardoublylist() {
start = NULL;
last = NULL;
}
};
int main() {
int c;
circulardoublylist cdl;
while (1) //perform switch operation {
cout<<"1.Insert at Beginning"<<endl;
cout<<"2.Insert at End"<<endl;
cout<<"3.Insert at Position"<<endl;
cout<<"4.Delete at Position"<<endl;
cout<<"5.Update Node"<<endl;
cout<<"6.Search Element"<<endl;
cout<<"7.Display List"<<endl;
cout<<"8.Reverse List"<<endl;
cout<<"9.Exit"<<endl;
cout<<"输入您的选择： ";
cin>>c;
switch(c) {
case 1:
cdl.insert_begin();
break;
case 2:
cdl.insert_end();
break;
case 3:
cdl.insert_pos();
break;
case 4:
cdl.delete_pos();
break;
case 5:
cdl.update();
break;
case 6:
cdl.search();
break;
case 7:
cdl.display();
break;
case 8:
cdl.reverse();
break;
case 9:
exit(1);
default:
cout<<"选择错误"<<endl;
}
}
return 0;
}
nod* circulardoublylist::create_node(int v) {
count++;
struct nod *t;
t = new(struct nod);
t->info = v;
t->n = NULL;
t->p = NULL;
return t;
}
void circulardoublylist::insert_begin() {
int v;
cout<<endl<<"输入要插入的元素： ";
cin>>v;
struct nod *t;
t = create_node(v);
if (start == last && start == NULL) {
cout<<"元素插入空lis-t"<<endl;
start = last = t;
start->n = last->n = NULL;
start->p = last->p = NULL;
} else {
t->n = start;
start->p = t;
start = t;
start->p = last;
last->n = start;
cout<<"元素已插入"<<endl;
}
}
void circulardoublylist::insert_end() {
int v;
cout<<endl<<"输入要插入的元素： ";
cin>>v;
struct nod *t;
t = create_node(v);
if (start == last && start == NULL) {
cout<<"元素插入空lis-t"<<endl;
start = last = t;
start->n= last->n = NULL;
start->p = last->p= NULL;
} else {
last->n= t;
t->p= last;
last = t;
start->p = last;
last->n= start;
}
}
void circulardoublylist::insert_pos() {
int v, pos, i;
cout<<endl<<"输入要插入的元素： ";
cin>>v;
cout<<endl<<"Enter the position of 元素已插入: ";
cin>>pos;
struct nod *t, *s, *ptr;
t = create_node(v);
if (start == last && start == NULL) {
if (pos == 1) {
start = last = t;
start->n = last->n = NULL;
start->p = last->p = NULL;
} else {
cout<<"位置超出范围"<<endl;
count--;
return;
}
} else {
if (count < pos) {
cout<<"位置超出范围"<<endl;
count--;
return;
}
s = start;
for (i = 1;i <= count;i++) {
ptr = s;
s = s->n;
if (i == pos - 1) {
ptr->n = t;
t->p= ptr;
t->n= s;
s->p = t;
cout<<"元素已插入"<<endl;
break;
}
}
}
}
void circulardoublylist::delete_pos() {
int pos, i;
nod *ptr, *s;
if (start == last && start == NULL) {
cout<<"List is empty, nothing to delete"<<endl;
return;
}
cout<<endl<<"输入要删除的元素的位置： ";
cin>>pos;
if (count < pos) {
cout<<"位置超出范围"<<endl;
return;
}
s = start;
if(pos == 1) {
count--;
last->n = s->n;
s->n->p = last;
start = s->n;
free(s);
cout<<"元素已删除"<<endl;
return;
}
for (i = 0;i < pos - 1;i++ ) {
s = s->n;
ptr = s->p;
}
ptr->n = s->n;
s->n->p = ptr;
if (pos == count) {
last = ptr;
}
count--;
free(s);
cout<<"元素已删除"<<endl;
}
void circulardoublylist::update() {
int v, i, pos;
if (start == last && start == NULL) {
cout<<"The List is empty, nothing to update"<<endl;
return;
}
cout<<endl<<"输入要更新的节点的位置： ";
cin>>pos;
cout<<"输入新值： ";
cin>>v;
struct nod *s;
if (count < pos) {
cout<<"位置超出范围"<<endl;
return;
}
s = start;
if (pos == 1) {
s->info = v;
cout<<"节点已更新"<<endl;
return;
}
for (i=0;i < pos - 1;i++) {
s = s->n;
}
s->info = v;
cout<<"节点已更新"<<endl;
}
void circulardoublylist::search() {
int pos = 0, v, i;
bool flag = false;
struct nod *s;
if (start == last && start == NULL) {
cout<<"The List is empty, nothing to search"<<endl;
return;
}
cout<<endl<<"输入要搜索的值： ";
cin>>v;
s = start;
for (i = 0;i < count;i++) {
pos++;
if (s->info == v) {
cout<<"Element "<<v<<" 在以下位置找到： "<<pos<<endl;
flag = true;
}
s = s->n;
}
if (!flag)
cout<<"在lis中找不到元素t"<<endl;
}
void circulardoublylist::display() {
int i;
struct nod *s;
if (start == last && start == NULL) {
cout<<"The List is empty, nothing to display"<<endl;
return;
}
s = start;
for (i = 0;i < count-1;i++) {
cout<<s->info<<"<->";
s = s->n;
}
cout<<s->info<<endl;
}
void circulardoublylist::reverse() {
if (start == last && start == NULL) {
cout<<"The List is empty, nothing to reverse"<<endl;
return;
}
struct nod *p1, *p2;
p1 = start;
p2 = p1->n;
p1->n = NULL;
p1->p= p2;
while (p2 != start) {
p2->p = p2->n;
p2->n = p1;
p1 = p2;
p2 = p2->p;
}
last = start;
start = p1;
cout<<"列表反转"<<endl;
}输出结果
1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 1 输入要插入的元素： 7 元素插入空lis-t 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 1 输入要插入的元素： 6 元素已插入 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 2 输入要插入的元素： 4 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 2 输入要插入的元素： 5 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 7 6<->7<->4<->5 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 6 输入要搜索的值： 7 Element 7 在以下位置找到： 2 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 6 输入要搜索的值： 2 在lis中找不到元素t 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 4 输入要删除的元素的位置： 4 元素已删除 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 3 输入要插入的元素： 5 Enter the position of 元素已插入: 2 元素已插入 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 7 6<->5<->7<->4 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 8 列表反转 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 7 4<->7<->5<->6 1.Insert at Beginning 2.Insert at End 3.Insert at Position 4.Delete at Position 5.Update Node 6.Search Element 7.Display List 8.Reverse List 9.Exit 输入您的选择： 9