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#include <stdio.h>
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#include <stdlib.h>
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// Node structure definition
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struct Node {
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    int data;
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    struct Node* next;
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};
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// Function to create a new node
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struct Node* createNode(int data) {
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    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
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    if (!newNode) {
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        printf("Memory allocation failed!\n");
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        exit(1);
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    }
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    newNode->data = data;
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    newNode->next = NULL;
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    return newNode;
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}
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// Function to insert a node at the end
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void insertAtEnd(struct Node** head, int data) {
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    struct Node* newNode = createNode(data);
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    if (*head == NULL) {
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        *head = newNode;
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        return;
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    }
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    struct Node* temp = *head;
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    while (temp->next != NULL)
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        temp = temp->next;
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    temp->next = newNode;
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}
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// Function to insert a node at the beginning
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void insertAtBeginning(struct Node** head, int data) {
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    struct Node* newNode = createNode(data);
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    newNode->next = *head;
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    *head = newNode;
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}
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// Function to delete a node with a given key
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void deleteNode(struct Node** head, int key) {
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    struct Node* temp = *head, *prev = NULL;
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    // If head node itself holds the key
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    if (temp != NULL && temp->data == key) {
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        *head = temp->next;
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        free(temp);
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        return;
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    }
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    // Search for the key
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    while (temp != NULL && temp->data != key) {
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        prev = temp;
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        temp = temp->next;
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    }
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    // Key not found
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    if (temp == NULL) {
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        printf("Node with value %d not found!\n", key);
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        return;
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    }
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    // Unlink the node and free memory
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    prev->next = temp->next;
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    free(temp);
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}
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// Function to search for a node
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int search(struct Node* head, int key) {
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    struct Node* temp = head;
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    while (temp != NULL) {
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        if (temp->data == key)
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            return 1; // Found
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        temp = temp->next;
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    }
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    return 0; // Not found
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}
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// Function to display the linked list
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void display(struct Node* head) {
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    struct Node* temp = head;
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    if (head == NULL) {
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        printf("List is empty!\n");
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        return;
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    }
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    while (temp != NULL) {
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        printf("%d -> ", temp->data);
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        temp = temp->next;
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    }
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    printf("NULL\n");
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}
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// Main function to demonstrate linked list operations
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int main() {
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    struct Node* head = NULL;
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    int choice, value, key;
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    while (1) {
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        printf("\nMenu:\n");
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        printf("1. Insert at Beginning\n");
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        printf("2. Insert at End\n");
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        printf("3. Delete Node\n");
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        printf("4. Search Node\n");
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        printf("5. Display List\n");
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        printf("6. Exit\n");
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        printf("Enter your choice: ");
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        scanf("%d", &choice);
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        switch (choice) {
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            case 1:
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                printf("Enter value to insert at beginning: ");
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                scanf("%d", &value);
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                insertAtBeginning(&head, value);
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                break;
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            case 2:
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                printf("Enter value to insert at end: ");
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                scanf("%d", &value);
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                insertAtEnd(&head, value);
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                break;
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            case 3:
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                printf("Enter value to delete: ");
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                scanf("%d", &key);
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                deleteNode(&head, key);
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                break;
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            case 4:
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                printf("Enter value to search: ");
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                scanf("%d", &key);
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                printf("Search result: %s\n", search(head, key) ? "Found" : "Not Found");
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                break;
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            case 5:
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                printf("Linked List: ");
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                display(head);
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                break;
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            case 6:
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                printf("Exiting program...\n");
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                exit(0);
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                break;
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            default:
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                printf("Invalid choice! Please enter a valid option.\n");
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        }
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    }
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    return 0;
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}