#include<stdio.h>
#include<stdlib.h>
struct node
{
    int data;
    struct node* link;
}*head=NULL,*temp=NULL,*last=NULL;

int len,takenode=1;

int main()
{
    int ch;
    while(1)
    {
        printf("-----------------------------\n");
        printf("Single Linked List Operations : \n");
        printf("-----------------------------\n");
        printf("1. Node Creation  \n");
        printf("2. Add at beginning\n");
        printf("3. Add at Last \n");
        printf("4. Add at any point\n");
        printf("5. Update any node\n");
        printf("6. Delete any node\n");
        printf("7. Search any node \n");
        printf("8. Display all elements\n");
        printf("9. Length\n");
        printf("10. Quit \n");
        printf("-----------------------------\n");
        printf("Enter your choice : ");
        scanf("%d",&ch);
        switch (ch)
        {
            case 1: node_creation();
            break;

            case 2: first_insert();
            break;

            case 3: last_insert();
            break;

            case 4 : addatanypoint();
            break;

            case 5 : update();
            break;

            case 6 : deleteanynode();
            break;

            case 7 : search();
            break;

            case 8: display();
            break;

            case 9 : len = length();
                    printf("Length is : %d\n\n",len);
            break;

            case 10 : exit(0);
            break;



            default:
            printf("Invalid Input.\n\n");

        }

    }
    return 0;
}

void node_creation()
{
    int num;
     printf("\nValue for Node %d--> :",takenode);
     takenode++;
        if(temp==NULL)
         {
            temp = (struct node*)malloc(sizeof(struct node));
            scanf("%d",&temp->data);
            head=temp;
        }
        else
            {
             temp = (struct node*)malloc(sizeof(struct node));
             scanf("%d",&temp->data);
             last->link=temp;
            }
        last=temp;

    last->link = NULL;
    printf("Node created successfully\n");
}

void first_insert()
{
     temp = (struct node*)malloc(sizeof(struct node));
     printf("Enter your Value :");
     scanf("%d",&temp->data);

     temp->link=head;
     head=temp;
     printf("Value successfully Inserted at the Beginning\n");

}

void last_insert()
{
     temp = (struct node*)malloc(sizeof(struct node));
     printf("Enter value ");
     scanf("%d",&temp->data);
     last->link=temp;
     temp->link=NULL;
     last=temp;

     printf("Value successfully Inserted at the End\n");

}

void addatanypoint()
{
    int loc;
    struct node* temp;
    struct node* p;
    printf("\nEnter location after which, the node will be inserted : \n");
    scanf("%d",&loc);

    len  = length();
    if(loc>length())
    {
        printf("\nInvalid input position... :( \nCurrent list is having %d nodes only\n\n",length());
    }
    else
    {
        int i=1;
        p = head;
        while(i<loc)
        {
            p = p->link;
            i++;
        }

        temp = (struct node*)malloc(sizeof(struct node));

        printf("enter new node data: \n");
        scanf("%d",&temp->data);
        temp->link=p->link;  //right connection
        p->link=temp;  // left connection
    }
}

void update()
{
    temp=head;
    int value,check=0;
    printf("Enter which value you want to update :\n");
    scanf("%d",&value);
    while(temp!=NULL)
    {
        if(temp->data == value){
            check++;
            break;
        }
        temp=temp->link;
    }
    if(check==0)
      printf("Sorry, your value is not found\n");
    else{
        printf("Value is found. Enter the new Value : \n");
        scanf("%d",&temp->data);
        printf("Value updated successfully\n");
    }

}

void search()
{
    struct node* temp;

    temp=head;

    int value,check=0;
    printf("\nEnter which value you want to search :\n");
    scanf("%d",&value);

    while(temp!=NULL)
    {
        if(temp->data == value){
            check++;
        }
        temp=temp->link;
    }

    if(check==0)
      printf("\nValue not found\n");
    else
     printf("\nValue found %d times :)\n",check);

}

void display()
{
    temp = head;

    if(temp==NULL)
    {
        printf("\nNo value in the list\n\n");
    }
    else{
        while(temp!=NULL)
        {
            printf("%d\t",temp->data);
            temp = temp->link;
        }
        printf("\n\n");
    }
}

int length()
{
    int count = 0;

    struct node* temp;
    temp = head;

    if(temp==NULL)
    {
        printf("\nNo value in the list\n\n");
    }

    while(temp!=NULL)
    {
        count++;
        temp = temp->link;
    }

    return count;
}

void deleteanynode()
 {
    int loc;

    printf("Enter the node number you want to delete : ");
    scanf("%d",&loc);

    if(loc>length())
        printf("Invalid position input\n");
    else if (loc==1)
    {
        temp=head;
        head =temp->link;
        temp->link=NULL;
        free(temp);
    }
    else
    {
        int i=1;
        struct node* p=head;
        struct node* q;
        while(i<loc-1)
        {
            p=p->link;
            i++;
        }
        q=p->link;
        p->link=q->link;
        q->link=NULL;
        free(q);
    }
}