# Check if given key is exist in doubly linked list

Here given code implementation process.

``````//C Program
//Find node in doubly linked list
#include <stdio.h>

#include <stdlib.h> //for malloc function

//create structure
struct Node {
int data;
struct Node *next;
struct Node *prev;
};

struct Node *head = NULL, *tail = NULL;

//insert Node element of end of linked list
void insert(int value) {

//Create a dynamic Node
struct Node *node = (struct Node *) malloc(sizeof(struct Node));
if (node == NULL) {
printf("Memory overflow\n");
} else {
//set data value
node->data = value;
node->next = NULL;
node->prev = NULL;
tail = node;

} else {
node->prev = tail;
tail->next = node;

tail = node;

}
}
}
//display element of Node
void display() {
if (temp == NULL) {
} else {

printf("\n Head to Tail Nodes : \n");
//Traverse doubly linked list from front to rear
while (temp != NULL) {
//print Node value
printf("%3d", temp->data);
temp = temp->next;
}
printf("\n Tail to Head Nodes : \n");

temp = tail;

//Traverse doubly linked list from rear to front
while (temp != NULL) {
//print Node value
printf("%3d", temp->data);
temp = temp->prev;
}
}

}
void find_node(int key)
{
{
return;
}
int status = 0;
while(front!=NULL && rear != NULL)
{
if(front->data == key || rear->data == key)
{
status = 1;
break;
}

if(front==rear || front->next == rear)
{

//means gievn key not exist
break;
}
//visit to new node
front = front -> next;
rear = rear ->prev;
}
if(status==1)
{
printf("\n Node %d is exist\n",key );
}
else
{
printf("\n Node %d are not exist\n",key );
}

}
int main() {

insert(8);
insert(2);
insert(23);
insert(-4);
insert(7);
insert(3);
insert(9);
//display all node

display();
find_node(-4);
find_node(11);
find_node(3);
return 0;
}```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````/*
C++ Program
Find node in doubly linked list
*/

#include<iostream>

using namespace std;
class Node {
public:
int data;
Node *next;
Node *prev;
Node(int value) {
this->data = value;
this->next = NULL;
this->prev = NULL;
}
};
public:
Node *tail;
this->tail = NULL;
}
void insert(int value) {
Node *node = new Node(value);
if (node == NULL) {
cout << "Memory overflow\n";
return;
}
this->tail = node;
} else {
node->prev = this->tail;
this->tail->next = node;
this->tail = node;
}
}
void display() {
if (temp == NULL) {
return;
}
cout << "\n Head to Tail Nodes : \n  ";
while (temp != NULL) {
cout << temp->data << "  ";
temp = temp->next;
}
temp = this->tail;
cout << "\n Tail to Head Nodes : \n  ";
while (temp != NULL) {
cout << temp->data << "  ";
temp = temp->prev;
}
}
void find_node(int key) {
return;
}
int status = 0;
Node *front = this->head, *rear = this->tail;
while (front != NULL && rear != NULL) {
if (front->data == key || rear->data == key) {
status = 1;
break;
}
if (front == rear || front->next == rear) {
break;
}
front = front->next;
rear = rear->prev;
}
if (status == 1) {
cout << "\n Node " << key << " is exist\n";
} else {
cout << "\n Node " << key << " are not exist\n";
}
}
};
int main() {
obj.insert(8);
obj.insert(2);
obj.insert(23);
obj.insert(-4);
obj.insert(7);
obj.insert(3);
obj.insert(9);
obj.display();
obj.find_node(-4);
obj.find_node(11);
obj.find_node(3);
return 0;
}```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````/*
Java Program
Find node in doubly linked list
*/
class Node {

public int data;

public Node next;

public Node prev;

public Node(int value) {
//Setup initial values of linked list node
this.data = value;
this.next = null;
this.prev = null;
}
}

public Node tail;

tail = null;
}
public void insert(int value) {
Node node = new Node(value);

if (node == null) {

System.out.print("Memory overflow\n");
return;
}
tail = node;
} else {
node.prev = tail;
tail.next = node;
tail = node;
}
}

public void display() {
if (temp == null) {
return;
}

System.out.print("\n Head to Tail Nodes : \n  ");

while (temp != null) {
System.out.print(temp.data + "  ");
temp = temp.next;
}

temp = tail;

System.out.print("\n Tail to Head Nodes : \n  ");

while (temp != null) {
System.out.print(temp.data + "  ");
temp = temp.prev;
}

}
public void find_node(int key) {

return;
}
int status = 0;
Node front = head, rear = tail;

while (front != null && rear != null) {

if (front.data == key || rear.data == key) {
status = 1;
break;
}

if (front == rear || front.next == rear) {
break;
}
front = front.next;
rear = rear.prev;
}

if (status == 1) {

System.out.print("\n Node " + key + " is exist\n");
} else {

System.out.print("\n Node " + key + " are not exist\n");
}
}

public static void main(String[] args) {
obj.insert(8);
obj.insert(2);
obj.insert(23);
obj.insert(-4);
obj.insert(7);
obj.insert(3);
obj.insert(9);
//display all node

obj.display();
obj.find_node(-4);
obj.find_node(11);
obj.find_node(3);
}

}```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````/*
C# Program
Find node in doubly linked list
*/
using System;
public class Node {

public int data;

public Node next;

public Node prev;

public Node(int value) {
//Setup initial values of linked list node
this.data = value;
this.next = null;
this.prev = null;
}
}

public Node tail;

tail = null;
}
public void insert(int value) {
Node node = new Node(value);

if (node == null) {

Console.Write("Memory overflow\n");
return;
}
tail = node;
} else {
node.prev = tail;
tail.next = node;
tail = node;
}
}

public void display() {
if (temp == null) {
return;
}

Console.Write("\n Head to Tail Nodes : \n  ");

while (temp != null) {
Console.Write(temp.data + "  ");
temp = temp.next;
}

temp = tail;

Console.Write("\n Tail to Head Nodes : \n  ");

while (temp != null) {
Console.Write(temp.data + "  ");
temp = temp.prev;
}

}
public void find_node(int key) {

return;
}
int status = 0;
Node front = head, rear = tail;

while (front != null && rear != null) {

if (front.data == key || rear.data == key) {
status = 1;
break;
}

if (front == rear || front.next == rear) {
break;
}
front = front.next;
rear = rear.prev;
}

if (status == 1) {

Console.Write("\n Node " + key + " is exist\n");
} else {

Console.Write("\n Node " + key + " are not exist\n");
}
}

public static void Main(String[] args) {
obj.insert(8);
obj.insert(2);
obj.insert(23);
obj.insert(-4);
obj.insert(7);
obj.insert(3);
obj.insert(9);
//display all node

obj.display();
obj.find_node(-4);
obj.find_node(11);
obj.find_node(3);
}

}```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````# Python 3 Program
# Find node in doubly linked list

class Node :

def __init__(self, value) :
self.data = value
self.next = None
self.prev = None

def __init__(self) :
self.tail = None

def insert(self, value) :
node = Node(value)
if (node == None) :
print("Memory overflow\n")
return

self.tail = node
else :
node.prev = self.tail
self.tail.next = node
self.tail = node

def display(self) :
if (temp == None) :
return

print("\n Head to Tail Nodes :  ")
while (temp != None) :
print(temp.data ,end="  ")
temp = temp.next

temp = self.tail
print("\n Tail to Head Nodes :  ")
while (temp != None) :
print(temp.data ,end="  ")
temp = temp.prev

def find_node(self, key) :
return

status = 0
rear = self.tail
while (front != None and rear != None) :
if (front.data == key or rear.data == key) :
status = 1
break

if (front == rear or front.next == rear) :
break

front = front.next
rear = rear.prev

if (status == 1) :
print("\n Node ", key ," is exist")
else :
print("\n Node ", key ," are not exist")

def main() :
obj.insert(8)
obj.insert(2)
obj.insert(23)
obj.insert(-4)
obj.insert(7)
obj.insert(3)
obj.insert(9)
obj.display()
obj.find_node(-4)
obj.find_node(11)
obj.find_node(3)

if __name__ == "__main__":
main()```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````# Ruby Program
# Find node in doubly linked list

class Node
attr_accessor :data, :next, :prev
def initialize(value)
self.data = value
self.next = nil
self.prev = nil
end
end

def initialize()
@tail = nil
end
def insert(value)
node = Node.new(value)
if (node == nil)
print("Memory overflow\n")
return
end
@tail = node
else
node.prev = @tail
@tail.next = node
@tail = node
end
end
def display()
if (temp == nil)
return
end
print("\n Head to Tail Nodes  :\n  ")
while (temp != nil)
print(temp.data ,"  ")
temp = temp.next
end
temp = @tail
print("\n Tail to Head Nodes  :\n  ")
while (temp != nil)
print(temp.data ,"  ")
temp = temp.prev
end
end
def find_node(key)
return
end
status = 0
rear = @tail
while (front != nil and rear != nil)
if (front.data == key or rear.data == key)
status = 1
break
end
if (front == rear or front.next == rear)
break
end
front = front.next
rear = rear.prev
end
if (status == 1)
print("\n Node ", key ," is exist\n")
else
print("\n Node ", key ," are not exist\n")
end
end
end
def main()
obj.insert(8)
obj.insert(2)
obj.insert(23)
obj.insert(-4)
obj.insert(7)
obj.insert(3)
obj.insert(9)
obj.display()
obj.find_node(-4)
obj.find_node(11)
obj.find_node(3)
end

main()```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````<?php
/*
Php Program
Find node in doubly linked list
*/

class Node {
public \$data;
public \$next;
public \$prev;

function __construct(\$value) {
\$this->data = \$value;
\$this->next = null;
\$this->prev = null;
}
}
public \$tail;

function __construct() {
\$this->tail = null;
}
public  function insert(\$value) {
\$node = new Node(\$value);
if (\$node == null) {
echo("Memory overflow\n");
return;
}
\$this->tail = \$node;
} else {
\$node->prev = \$this->tail;
\$this->tail->next = \$node;
\$this->tail = \$node;
}
}
public  function display() {
if (\$temp == null) {
return;
}
echo("\n Head to Tail Nodes : \n  ");
while (\$temp != null) {
echo(\$temp->data ."  ");
\$temp = \$temp->next;
}
\$temp = \$this->tail;
echo("\n Tail to Head Nodes : \n  ");
while (\$temp != null) {
echo(\$temp->data ."  ");
\$temp = \$temp->prev;
}
}
public  function find_node(\$key) {
return;
}
\$status = 0;
\$rear = \$this->tail;
while (\$front != null && \$rear != null) {
if (\$front->data == \$key || \$rear->data == \$key) {
\$status = 1;
break;
}
if (\$front == \$rear || \$front->next == \$rear) {
break;
}
\$front = \$front->next;
\$rear = \$rear->prev;
}
if (\$status == 1) {
echo("\n Node ". \$key ." is exist\n");
} else {
echo("\n Node ". \$key ." are not exist\n");
}
}
}

function main() {
\$obj->insert(8);
\$obj->insert(2);
\$obj->insert(23);
\$obj->insert(-4);
\$obj->insert(7);
\$obj->insert(3);
\$obj->insert(9);
\$obj->display();
\$obj->find_node(-4);
\$obj->find_node(11);
\$obj->find_node(3);
}
main();```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````/*
Node Js Program
Find node in doubly linked list
*/

class Node {

constructor(value) {
this.data = value;
this.next = null;
this.prev = null;
}
}

constructor() {
this.tail = null;
}
insert(value) {
var node = new Node(value);
if (node == null) {
process.stdout.write("Memory overflow\n");
return;
}
this.tail = node;
} else {
node.prev = this.tail;
this.tail.next = node;
this.tail = node;
}
}
display() {
if (temp == null) {
return;
}
process.stdout.write("\n Head to Tail Nodes : \n  ");
while (temp != null) {
process.stdout.write(temp.data + "  ");
temp = temp.next;
}
temp = this.tail;
process.stdout.write("\n Tail to Head Nodes : \n  ");
while (temp != null) {
process.stdout.write(temp.data + "  ");
temp = temp.prev;
}
}
find_node(key) {
return;
}
var status = 0;
var rear = this.tail;
while (front != null && rear != null) {
if (front.data == key || rear.data == key) {
status = 1;
break;
}
if (front == rear || front.next == rear) {
break;
}
front = front.next;
rear = rear.prev;
}
if (status == 1) {
process.stdout.write("\n Node " + key + " is exist\n");
} else {
process.stdout.write("\n Node " + key + " are not exist\n");
}
}
}

function main() {
obj.insert(8);
obj.insert(2);
obj.insert(23);
obj.insert(-4);
obj.insert(7);
obj.insert(3);
obj.insert(9);
obj.display();
obj.find_node(-4);
obj.find_node(11);
obj.find_node(3);
}

main();```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````
``````/*
Swift 4 Program
Find node in doubly linked list
*/

class Node {
var data: Int;
var next: Node? ;
var prev: Node? ;
init(_ value: Int) {
self.data = value;
self.next = nil;
self.prev = nil;
}
}
var tail: Node? ;
init() {
self.tail = nil;
}
func insert(_ value: Int) {
let node: Node? = Node(value);
if (node == nil) {
print("Memory overflow\n");
return;
}
self.tail = node;
} else {
node!.prev = self.tail;
self.tail!.next = node;
self.tail = node;
}
}
func display() {
if (temp == nil) {
return;
}
print("\n Head to Tail Nodes : ");
while (temp != nil) {
print(temp!.data ,terminator:"  ");
temp = temp!.next;
}
temp = self.tail;
print("\n Tail to Head Nodes : ");
while (temp != nil) {
print(temp!.data ,terminator:"  ");
temp = temp!.prev;
}
}
func find_node(_ key: Int) {
return;
}
var status: Int = 0;
var rear: Node? = self.tail;
while (front != nil && rear != nil) {
if (front!.data == key || rear!.data == key) {
status = 1;
break;
}
if (front === rear || front!.next === rear) {
break;
}
front = front!.next;
rear = rear!.prev;
}
if (status == 1) {
print("\n Node ", key ," is exist");
} else {
print("\n Node ", key ," are not exist");
}
}
}
func main() {
obj.insert(8);
obj.insert(2);
obj.insert(23);
obj.insert(-4);
obj.insert(7);
obj.insert(3);
obj.insert(9);
obj.display();
obj.find_node(-4);
obj.find_node(11);
obj.find_node(3);
}
main();```
```

#### Output

`````` Head to Tail Nodes :
8  2 23 -4  7  3  9
9  3  7 -4 23  2  8
Node -4 is exist

Node 11 are not exist

Node 3 is exist
``````

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