Added Files for Linked List programs in C++

c++/CircularLL.cpp

@@ -0,0 +1,66 @@
+#include <iostream>
+using namespace std;
+class Node
+{
+public:
+    int data;
+    Node *next;
+};
+Node *Insert(int pos,int x,Node *head)
+{
+    Node *t,*p;
+    if (pos ==0)
+    {
+        if(head == NULL){
+        t = new Node;
+        t->data = x;
+        t->next = t;
+        head=t;
+        }
+        else
+        {
+            Node *temp;
+            temp = new Node;
+            while(temp->next!=head) // for going towards the last node
+                temp=temp->next;
+            temp->next=t;
+            t->data=x;
+            t->next=head;
+        }
+    }
+    else if(pos >0 )
+    {
+        p = head;
+        for (int i = 0; i < pos-1 ; i++)
+            p=p->next;
+            t = new Node;
+            t->data = x;
+            t->next = p->next;
+            p->next = t;
+    }
+    return head;
+}
+void display(Node *head)
+{
+    Node *p=head;
+    do
+    {
+    cout<<p->data<<" ";
+    p=p->next;
+    }while (p!=head);
+}
+int main()
+{
+    int n,x;
+    Node *first=NULL;
+    cout<<"Enter the number of elements in the list: ";
+    cin>>n;
+    cout<<"Enter the elements of the list: ";
+    for (int i = 0; i < n; i++)
+    {
+        cin>>x;
+        first=Insert(i,x,first);
+    }
+    display(first);
+return 0;
+}

c++/DoublyLL.cpp

@@ -0,0 +1,60 @@
+#include <iostream>
+using namespace std;
+class Node
+{
+public:
+    Node *previous;
+    int data;
+    Node *next;
+};
+Node *Insert(int pos,int x, Node *head)
+{
+     Node *t,*p;
+     if(pos ==0)
+     {
+        t=new Node;
+        t->data=x;
+        t->previous=NULL;
+        t->next=head;
+        if(head !=NULL)
+        head->previous=t;
+        head=t;
+     }
+     else
+     {
+        p=head;
+        for(int i=0;i<pos-1;i++)
+            p=p->next;
+        t=new Node;
+        t->data=x;
+        t->previous=p;
+        t->next=p->next;
+        if(p->next)
+        p->next->previous=t;
+        p->next=t;
+     }
+     return head;
+}
+void display(Node *head)
+{
+    Node *p=head;
+    while(p!=NULL)
+    {
+        cout<<p->data<<" ";
+        p=p->next;
+    }
+}
+int main()
+{
+    Node *first=NULL;
+    int n,x,pos;
+    cout<<"Enter the number of elements in the list: ";
+    cin>>n;
+    for(int i=0;i<n;i++)
+    {
+        cin>>x;
+        first=Insert(i,x,first);
+    }
+    display(first);
+return 0;
+}

c++/LoopinLL.cpp

@@ -0,0 +1,98 @@
+#include <iostream>
+using namespace std;
+class Node
+{
+public:
+    int data;
+    Node *next;
+};
+Node *Insert(int pos,int x,Node *head)
+{
+    Node *t,*p;
+    if(pos==0)
+    {
+        t=new Node;
+        t->data=x;
+        t->next=head;
+        head=t;
+    }
+    else if(pos >0)
+    {
+        p=head;
+        for(int i=0;i<pos-1 &&p;i++)
+        p=p->next;
+        if(p)
+        {
+            t=new Node;
+            t->data=x;
+            t->next=p->next;
+            p->next=t;
+        }
+    }
+    return head;
+}
+void Display(Node *head)
+{
+    Node *p=head;
+    while(p)
+    {
+        cout<<p->data<<" ";
+        p=p->next;
+    }
+}
+bool Loop(Node *head)
+{
+    bool var;
+    Node *p,*q;
+    p=head;
+    q=head;
+    // while(p && q && p!=q)
+    // {
+    //     p=p->next;
+    //     q=q->next;
+    //     if(q!=NULL)
+    //     q->next;
+    //     else
+    //     q=q;
+    // }    
+    // if(p==q)
+    // var =true;
+    // else
+    // var = false;
+    do
+    {
+    p=p->next;
+    q=q->next;
+    q=q?q->next:q;
+    }
+    while(p && q && p!=q);
+    if(p==q)
+    var=true;
+    else
+    var=false;
+    return var;
+}
+int main()
+{
+Node *first=NULL;
+int x;
+int n;
+cout<<" Enter the Number of elements you want to enter "<<endl;
+cin>>n;
+for(int i=0;i<n;i++)
+{
+    cin>>x;
+    first=Insert(i,x,first);
+}
+// Display(first);
+// cout<<endl;
+Node *t1,*t2;
+// t1=first->next->next;
+// t2=first->next->next->next->next;
+// t2->next=t1;
+if(Loop(first))
+cout<<" linked List has a Loop "<<endl;
+else
+cout<<" linked list does not have a Loop "<<endl;
+return 0;
+}

c++/SearchinLinkedList.cpp

@@ -0,0 +1,70 @@
+#include <iostream>
+using namespace std;
+class Node
+{
+    public:
+    int data;
+    Node *next;
+}
+*first;
+void Create(int A[],int n)
+{
+    Node *t,*last;
+    int i;
+    first=new Node;
+    first->data=A[0];
+    first->next=NULL;
+    last=first;
+    for(i=1;i<n;i++)
+    {
+        t=new Node;
+        t->data=A[i];
+        t->next=NULL;
+        last->next=t;
+        last=t;
+    }
+}
+Node* Search(Node *head,int key)
+{
+    Node *p=head;
+    while(p!=NULL)
+    {
+        if(p->data==key)
+        {
+            cout<<"\nElement found";
+            return p;
+        }
+        p=p->next;
+    }
+}
+Node* RecSearch(Node *head,int key)
+{
+    Node *p=head;
+    if(p==NULL)
+    return NULL;
+    if(p->data==key)
+    return p;
+    else
+    return RecSearch(p->next,key);
+}
+int main()
+{
+    int n,i,a[100];
+    cout<<"Enter the size of the array : ";
+    cin>>n;
+    cout<<"Enter the elements of the array : ";
+    for(i=0;i<n;i++)
+    {
+        cin>>a[i];
+    }
+    Create(a,n);
+    int key;
+    cout<<"\nEnter the element to be searched : ";
+    cin>>key;
+    Node *p=RecSearch(first,key);
+    if(p==NULL)
+    cout<<"\nElement not found";
+    else
+    cout<<"\nElement found  ";
+return 0;
+}