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DS/C/Lab/Week9/Doubly_Circular_LL.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct cnode *cnptr;
+typedef struct cnode
+{
+    int data;
+    cnptr next;
+    cnptr prev;
+}cnode;
+cnptr last=NULL;
+
+cnptr createCnode(int val)
+{
+    cnptr temp=(cnptr)malloc(sizeof(cnode));
+    temp->data=val;
+    temp->next=NULL;
+    temp->prev=NULL;
+    return temp;
+}
+void insertBegin(int val)
+{
+    cnptr temp=createCnode(val);
+    if(last==NULL)
+    {
+        last=temp;
+        last->next=last;
+        last->prev=last;
+    }
+    else
+    {
+        temp->next=last->next;//head
+        last->next->prev=temp;
+        temp->prev=last;
+        last->next=temp;
+    }
+}
+void deleteend()
+{
+    cnptr current;
+    if(last==NULL)
+    {
+        printf("List is empty");
+    }
+    else
+    {
+        cnptr previous=last->prev;
+        previous->next=last->next;
+        last->next->prev=previous;
+        free(last);
+        last=previous;
+    }
+}
+void revtraverse()
+{
+    cnptr current=last;
+    printf("%d ",current->data);
+    current=current->prev;
+    while(current!=last)
+    {
+        printf("%d ",current->data);
+        current=current->prev;
+    }
+    printf("\n");
+}
+void traverse()
+{
+    cnptr current=last;
+    current=current->next;
+    while(current!=last)
+    {
+        printf("%d ",current->data);
+        current=current->next;
+    }
+    printf("%d\n",current->data);
+}
+int main()
+{
+    char contin='y';
+    int choice;
+    while(contin=='y')
+    {
+        printf("What do you want to do? \n 1. For inserting at beginning \n 2. For deleting at the end. \n 3. For traversing the doubly LL\n");
+        scanf("%d",&choice);
+        switch(choice)
+        {
+        case 1:
+            {
+                int val;
+                printf("Enter the value\n");
+                scanf("%d",&val);
+                insertBegin(val);
+                break;
+            }
+        case 2:
+            {
+                deleteend();
+                printf("Element deleted\n");
+                break;
+            }
+        case 3:
+            {
+                printf("elements of the list are\n");
+                traverse();
+                break;
+            }
+        }
+        printf("continue?(y/n)\n");
+        fflush(stdin);
+        scanf("%c",&contin);
+    }
+
+}
+
+