Added a doubly List

doubly_LList.cpp

@@ -0,0 +1,133 @@
+#include<stdio.h>
+#include<stdlib.h>
+struct Node{
+	struct Node *prev;
+	int data;
+	struct Node *next;
+}*first;
+void create(int a[],int n){
+	struct Node *t,*last;
+	first=(struct Node *)malloc(sizeof(struct Node));
+	first->data=a[0];
+	first->prev=NULL;
+	first->next=NULL;
+	last=first;
+	for(int i=1;i<n;i++){
+		t=(struct Node *)malloc(sizeof(struct Node));
+		t->data=a[i];
+		t->next=NULL;
+		last->next=t;
+		t->prev=last;
+		last=t;
+	}
+
+}
+void display(struct Node *p){
+	while(p){
+		printf("%5d",p->data);
+		p=p->next;
+	}
+}
+void insert(int pos,int x){
+	struct Node *t,*p=first;
+	t=(struct Node *)malloc(sizeof(struct Node));
+	t->data=x;
+	if(pos==0){
+		if(first==NULL){
+			first=t;
+			t->prev=NULL;
+			t->next=NULL;	
+		}else{
+			t->prev=NULL;
+			t->next=first;
+			first->prev=t;
+			first=t;
+		}
+	}
+	else{
+		for(int i=0;i<pos-1;i++){
+			p=p->next;
+		}
+		t->next=p->next;
+		t->prev=p;
+		if(p->next!=NULL){
+			p->next->prev=t;
+		}
+		p->next=t;
+	}
+}
+int Delete(int pos){
+	struct Node *p=first;
+	int x;
+	if(pos==1){
+		first=first->next;
+		x=p->data;
+		delete p;
+		if(first){
+			first->prev=NULL;
+		}
+	}
+	else{
+		for(int i=0;i<pos-1;i++){
+			p=p->next;
+		}
+		p->prev->next=p->next;
+		if(p->next){
+			p->next->prev=p->prev;
+		}
+		x=p->data;
+		delete p;
+	}
+	return x;
+}
+void reverse(struct Node *p){
+	struct Node *temp;
+	while(p){
+		temp=p->next;
+		p->next=p->prev;
+		p->prev=temp;
+		p=p->prev;
+		if(p!=NULL && p->next==NULL){
+			first=p;
+		}
+	}
+}
+int mid(struct Node *p){
+	struct Node *q=first;
+	while(q){
+		q=q->next;
+		if(q){
+			q=q->next;
+		}
+		if(q){
+			p=p->next;
+		}
+	}
+	return p->data;
+}
+int main(){
+	int n,pos,x;
+	printf("Enter the number of Nodes: ");
+	scanf("%d",&n);
+	int *a=(int *)malloc(n*sizeof(int));
+	printf("Enter the data for nodes:\n");
+	for(int i=0;i<n;i++){
+		scanf("%d",&a[i]);
+	}
+	create(a,n);
+	display(first);
+	printf("\nEnter the data and position to insert: ");
+	scanf("%d%d",&x,&pos);
+	insert(pos,x);
+	display(first);
+	printf("\nEnter the position to delete: ");
+	scanf("%d",&pos);
+	printf("%d\n",Delete(pos));
+	display(first);
+	reverse(first);
+	printf("\nDisplaying the reversed list:\n");
+	display(first);
+	printf("\nmiddle of linked list is: %d",mid(first));
+
+	return 0;
+}