Add code to implement a Circular Linked List

C/Linked Lists/circular_ll.c

@@ -0,0 +1,223 @@
+// Circular Linked List
+
+#include <stdio.h>
+#include <conio.h>
+#include <stdlib.h>
+
+struct Node {
+    int data;
+    struct Node *next;
+};
+
+struct Node *node = NULL, *list = NULL, *last = NULL, *temp = NULL, *p = NULL;
+int count = 0;
+
+struct Node *createNode(int info) {
+    node = (struct Node*)malloc(sizeof(struct Node));
+    node->data = info;
+    node->next = NULL;
+    count++;
+    return node;
+}
+
+void AddAtFront(int info) {
+    node = createNode(info);
+    if (list == NULL) {
+        list = last = node;
+        last->next = list; // Point last to the first node
+    } else {
+        node->next = list;
+        list = node;
+        last->next = list; // Maintain circular link
+    }
+}
+
+void AddAtEnd(int info) {
+    node = createNode(info);
+    if (list == NULL) {
+        list = last = node;
+        last->next = list; // Point last to the first node
+    } else {
+        last->next = node;
+        last = node;
+        last->next = list; // Maintain circular link
+    }
+}
+
+void AddAtPosition(int info, int pos) {
+    if (pos == 1) {
+        AddAtFront(info);
+    } else if (pos == (count + 1)) {
+        AddAtEnd(info);
+    } else {
+        node = createNode(info);
+        temp = list;
+        for (int i = 1; i < pos - 1; i++) {
+            temp = temp->next;
+        }
+        node->next = temp->next;
+        temp->next = node;
+    }
+}
+
+void DeleteAtFront() {
+    if (list == NULL) {
+        printf("\nList is Empty!\n");
+    } else {
+        temp = list;
+        if (list == last) { // Only one node in the list
+            list = last = NULL;
+        } else {
+            list = list->next;
+            last->next = list; // Maintain circular link
+        }
+        printf("\nNode deleted: %d\n", temp->data);
+        free(temp);
+        count--;
+    }
+}
+
+void DeleteAtEnd() {
+    if (list == NULL) {
+        printf("\nList is Empty!\n");
+    } else {
+        temp = list;
+        if (list == last) { // Only one node in the list
+            printf("\nNode deleted: %d\n", last->data);
+            free(last);
+            list = last = NULL;
+        } else {
+            while (temp->next != last) {
+                temp = temp->next;
+            }
+            printf("\nNode deleted: %d\n", last->data);
+            temp->next = list; // Maintain circular link
+            free(last);
+            last = temp;
+        }
+        count--;
+    }
+}
+
+void DeleteAtPosition(int pos) {
+    if (pos == 1) {
+        DeleteAtFront();
+    } else if (pos == count) {
+        DeleteAtEnd();
+    } else {
+        temp = list;
+        p = NULL;
+        for (int i = 1; i < pos; i++) {
+            p = temp;
+            temp = temp->next;
+        }
+        printf("\nNode deleted: %d\n", temp->data);
+        p->next = temp->next;
+        free(temp);
+        count--;
+    }
+}
+
+int Search(int info) {
+    int pos = 1;
+    if (list == NULL) {
+        printf("\nList is Empty!");
+        return -1;
+    } else {
+        temp = list;
+        do {
+            if (temp->data == info) {
+                return pos;
+            }
+            temp = temp->next;
+            pos++;
+        } while (temp != list);
+    }
+    return -1;
+}
+
+void SearchAndDelete(int info) {
+    int pos = Search(info);
+    if (pos != -1) {
+        DeleteAtPosition(pos);
+    } else {
+        printf("\nNo Data Found!");
+    }
+}
+
+void Display() {
+    if (list == NULL) {
+        printf("\nList is Empty!\n");
+    } else {
+        temp = list;    
+        do {
+            printf("%d -> ", temp->data);
+            temp = temp->next;
+        } while (temp != list);
+        printf("(back to %d)\n", list->data); // Indicate circular nature
+    }
+}
+
+void main() {
+    int choice, data, pos;
+
+    clrscr();
+
+    do {
+        printf("\nEnter choice: \n1. Add At Front\n2. Add At End\n3. Add At Position\n4. Delete At Front\n5. Delete At End\n6. Delete At Position\n7. Search\n8. Exit\n");
+        scanf("%d", &choice);
+        switch (choice) {
+            case 1: 
+                printf("\nEnter data: ");
+                scanf("%d", &data);
+                AddAtFront(data);
+                Display();
+                break;
+            case 2: 
+                printf("\nEnter data: ");
+                scanf("%d", &data);
+                AddAtEnd(data);
+                Display();
+                break;
+            case 3: 
+                printf("\nEnter data: ");
+                scanf("%d", &data);
+                printf("\nEnter position: ");
+                scanf("%d", &pos);
+                AddAtPosition(data, pos);
+                Display();
+                break;
+            case 4: 
+                DeleteAtFront();
+                Display();
+                break;
+            case 5: 
+                DeleteAtEnd();
+                Display();
+                break;
+            case 6: 
+                printf("\nEnter position: ");
+                scanf("%d", &pos);
+                DeleteAtPosition(pos);
+                Display();
+                break;
+            case 7: 
+                printf("\nEnter data: ");
+                scanf("%d", &data);
+                pos = Search(data);
+                if (pos != -1) {
+                    printf("\nPosition: %d\n", pos);
+                } else {
+                    printf("\nData Not Found!");
+                }
+                break;
+            case 8: 
+                printf("\nExiting...\n");
+                break;
+            default: 
+                printf("\nEnter valid choice!\n");
+        }
+    } while (choice != 8);
+
+    getch();
+}