Added a Program for Doubly Linked List.

DSA_CPP/creatingDoublyLL.c

@@ -0,0 +1,116 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef int itemType;
+
+//self referential structure
+typedef struct node
+{
+    itemType info;
+    struct node *link, *prev;
+}node;
+
+typedef struct List
+{
+    node *head, *tail;
+}List;
+
+node *createNode(itemType x)
+{
+    node *p;
+    p = (node *)malloc(1*sizeof(node));
+    if (p==NULL)
+    {
+        printf("Memory not allocated\n");
+        exit(1);
+    }
+    p->info = x;
+    p->link = NULL;
+    p->prev = NULL;
+    return p;
+}
+void show(List *lp)
+{
+    node *p;
+
+    p = lp->head;
+    printf("Linked list is: ");
+    while(p != NULL)
+    {
+        printf("%d---->", p->info);
+        p = p->link;
+    }
+    printf("NULL\n\n");
+}
+void showReverse(List *lp)
+{
+    node *p;
+
+    p = lp->tail;
+    printf("Linked list is: ");
+    while(p != NULL)
+    {
+        printf("%d---->", p->info);
+        p = p->prev;
+    }
+    printf("NULL\n\n");
+}
+
+void insertAtTail(List *lp, itemType x)
+{
+    node *p;
+
+    p = createNode(x);
+
+    if (lp->head == NULL)
+        lp->head = p;
+    else
+    {
+        lp->tail->link = p;
+        p->prev = lp->tail;
+    }
+    lp->tail = p;
+}
+
+void initialize(List *lp)
+{
+    lp->head = NULL;
+    lp->tail = NULL;
+}
+List *createList()
+{
+    List *lp;
+    itemType x;
+    int n, i;
+
+    //allocate space for head and tail
+    lp = (List *)malloc(sizeof(List));
+    if (lp==NULL)
+    {
+        printf("Memory not allocated\n");
+        exit(1);
+    }
+    initialize(lp);
+
+    printf("Enter count of items: ");
+    scanf("%d", &n);
+
+    srand(time(0));
+    for (i=0; i<n; ++i)
+    {
+        x = rand()%100;
+        insertAtTail(lp, x);
+    }
+    return lp;
+}
+
+int main()
+{
+    List *lp;
+
+    lp = createList();
+    show(lp);
+    showReverse(lp);
+
+    return 0;
+}