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// Online C compiler to run C program online
#include <stdio.h>
#include <stdlib.h>

typedef struct {
    void *next;
    int data;
} Node;

Node *head = NULL;

//add
Node *addNode(int data) {
    Node *new = NULL;
    //2 cases

    //if head is empty/null
    if (head == NULL) {
        new = malloc(sizeof(Node));
        if (new == NULL)
            return NULL;

        new->data = data;
        head = new;
        new->next = NULL;
    }
    else {
        new = malloc(sizeof(Node));
        if (new == NULL)
            return NULL;

        new->data = data;
        new->next = head;
        head = new;
    }

    return new;
}


//delete
int removeNode(int data) {
    Node *current = head;
    Node *prev = head;
    while (current != NULL) {
        if (current->data == data) {
            //if current is head
            if (current == head) {
                head = current->next;
            }
            else {
                prev->next = current->next;
                free(current);
                current = NULL;
            }

            return 1;
        }
        prev = current;
        current = current->next;
    }

    return 0;
}

//insert
Node *insertNode(int data, int position) {
    Node *current = head;
    while (current != NULL && position != 0) {
        position--;
    }
    if (position != 0) {
        printf("Request position too far into list\n");
        return NULL;
    }

    Node *new = malloc(sizeof(Node));
    if (new == NULL) {
        return NULL;
    }
    new->data = data;
    new->next = current->next;
    current->next = new;

    return new;
}


//print node
void printList() {
    Node *current = head;
    while (current != NULL) {
        printf("%d->", current->data);
        current = current->next;
    }
    printf("\n");
    return;
}

//menu options
void printMenu() {
    printf("1. Add node\n");
    printf("2. Delete node\n");
    printf("3. Insert node\n");
    printf("4. Print node\n");
    printf("5. Quit\n");
    printf(">>");
    return;

}

int main() {
    int option = 1;
    int arg1 = 0;
    int arg2 = 0;

    while (option != 5) {
        printMenu();
        int num_received = scanf("%d", &option);
        if (num_received == 1 && option > 0 && option <= 5)
        {
            switch (option) {
                case 1:
                    //add
                    printf("Enter data to insert: ");
                    scanf("%d", &arg1);
                    Node *new = addNode(arg1);
                    break;
                case 2:
                    //delete
                    printf("Enter data to delete: ");
                    scanf("%d", &arg1);
                    int success = removeNode(arg1);
                    if (!success) {
                        printf("Element not found!");
                    }
                    break;
                case 3:
                    int option2 = 0;
                    //insert
                    printf("Enter data to insert: ");
                    scanf("%d", &arg1);
                    printf("Enter Position: ");
                    scanf("%d", &arg2);
                    Node *new2 = insertNode(arg1, arg2);
                    if (new2 == NULL) {
                        printf("Insert Failed!\n");
                    }
                    break;
                case 4:
                    //print
                    printList();
                    break;
                case 5:
                    break;
            }
        }
    }

    return 0;
}