Circular Linked List Program with Basic Operations

data_structures/linked_list/circular_list_operations.c

@@ -0,0 +1,126 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct node {
+    int data;
+    struct node *next;
+};
+
+struct node *first = NULL;
+struct node *last = NULL;
+
+void create() {
+    int n, i;
+    struct node *pnode;
+
+    printf("Enter number of nodes: ");
+    scanf("%d", &n);
+
+    printf("Enter data of each node:\n");
+    for (i = 0; i < n; i++) {
+        pnode = (struct node*)malloc(sizeof(struct node));
+        if (!pnode) {
+            printf("Memory Allocation Failed\n");
+            return;
+        }
+
+        scanf("%d", &pnode->data);
+
+        if (first == NULL) {
+            first = last = pnode;
+        } else {
+            last->next = pnode;
+            last = pnode;
+        }
+        last->next = first;
+    }
+}
+
+void deletenode(int k) {
+    if (first == NULL) {
+        printf("List Empty\n");
+        return;
+    }
+
+    struct node *p = first, *prev = last;
+
+    do {
+        if (p->data == k)
+            break;
+        prev = p;
+        p = p->next;
+    } while (p != first);
+
+    if (p->data != k) {
+        printf("Node not found\n");
+        return;
+    }
+
+    if (first == last && p == first) {
+        first = last = NULL;
+    } else if (p == first) {
+        first = first->next;
+        last->next = first;
+    } else if (p == last) {
+        last = prev;
+        last->next = first;
+    } else {
+        prev->next = p->next;
+    }
+
+    free(p);
+    printf("Node Deleted\n");
+}
+
+void traverse() {
+    if (first == NULL) {
+        printf("List Empty\n");
+        return;
+    }
+
+    printf("Circular Linked List: ");
+    struct node *p = first;
+
+    do {
+        printf("%d ", p->data);
+        p = p->next;
+    } while (p != first);
+
+    printf("\n");
+}
+
+int main() {
+    int ch, k;
+
+    while (1) {
+        printf("\nMenu:\n");
+        printf("1. Create List\n");
+        printf("2. Delete Node\n");
+        printf("3. Traverse\n");
+        printf("4. Exit\n");
+        printf("Enter choice: ");
+        scanf("%d", &ch);
+
+        switch (ch) {
+            case 1:
+                create();
+                break;
+
+            case 2:
+                printf("Enter data to delete: ");
+                scanf("%d", &k);
+                deletenode(k);
+                break;
+
+            case 3:
+                traverse();
+                break;
+
+            case 4:
+                return 0;
+
+            default:
+                printf("Invalid Choice\n");
+        }
+    }
+}