#include<stdio.h>
#include<stdlib.h>
typedef struct st_info
{
    char name[50];
    int roll;
    struct st_info *next;
} data;
data *head = NULL;
data *list = NULL;


display()
{
    list = head;
    while(list != NULL)
    {
        printf("%s\n",list -> name);
        printf("%d\n",list -> roll);
        list = list -> next;
    }
    return;
}


void make_node(int n)
{
    int i;
    if(n==0)
    {
        head == NULL;
    }
    else
    {
        for(i=0; i<n; i++)
        {
            data *N = (data*)malloc(sizeof(data));
            printf("Enter your name: ");
            scanf(" %[^\n]s",N -> name);
            printf("Enter your roll: ");
            scanf("%d",&N -> roll);
            N -> next = NULL;
            if(head == NULL)
            {
                head = N;
                list = head;
            }
            else
            {
                list -> next = N;
                list = list -> next;
            }
        }
    }
}


void add_in_last()
{
    list = head;
    data *p = (data*)malloc(sizeof(data));
    printf("Enter a name: ");
    scanf(" %[^\n]s",p -> name);
    printf("Enter a roll: ");
    scanf("%d",&p -> roll);
    p -> next = NULL;
    while(list -> next!= NULL)
    {
        list = list -> next;
    }
    list -> next = p;

}

void insert_at_first()
{
    data *q = (data*)malloc(sizeof(data));
    printf("Enter your name: ");
    scanf(" %[^\n]s",q -> name);
    printf("Enter your roll: ");
    scanf("%d",&q -> roll);
    list = head;
    if(head == NULL)
    {
        head = q;

    }
    else
    {
        q -> next = head;
        head = q;
    }
}

void insert_in_nth(int n)
{
    data * temp = NULL;
    int count = 0;
    list = head;
    data *r = (data*)malloc(sizeof(data));
    printf("Enter a name: ");
    scanf(" %[^\n]s",r -> name);
    printf("Enter a roll: ");
    scanf("%d",&r -> roll);
    r -> next = NULL;
    if(head == NULL)
    {
        head = r;

    }
    else
    {
        while(list != NULL)
        {
            temp = list -> next;
            count++;
            if(count == n)
            {
                list -> next = r;
                r -> next = temp;
            }
            list = list -> next;
        }
    }



}

void delete_by_pos(int n)
{
    int i;
    data *temp1=head;
    if(n==1)
    {
        head = temp1->next;
        free(temp1);
        return;
    }
    for(i=1; i<n-1; i++)
    {
        temp1 = temp1 -> next;
    }
    data *temp2 = temp1 -> next;
    temp1 -> next = temp2 -> next;
    free(temp2);
}

void delete_by_valu(int n)
{
    data *list = head;
    data *temp1=list;
    while(list!=NULL)
    {
        if(head -> roll ==n)
        {
            head = temp1 -> next;
            free(temp1);
            return;
        }
        else
        {
            if(list -> roll == n)
            {
                data *temp2 = temp1 -> next;
                temp1 -> next = temp2 -> next;
                free(temp2);
                return;
            }
            temp1 = list;
            list = list -> next;
        }
    }
}

void search_by_pos(int n)
{
    data *list = head;
    int i;
    //data *temp = list;
    for(i=1; i<n; i++)
    {
        list = list -> next;
    }
    printf("%s\n",list -> name);
    printf("%d\n",list -> roll);
}

void search_by_valu(int n)
{
    data *list = head;
    while(list !=NULL)
    {
        if(list -> roll = n )
        {
            printf("%s",list -> name);
            printf("%d\n",list -> roll);
            return;
        }
        else
            list = list -> next;
    }
}

main()
{
    int n,m,x,y,z,h;
    printf("Enter you node amount: ");
    scanf("%d",&n);
    printf(".............\n");
    make_node(n);
    printf(".............\n");
    display();
    printf(".............\n");
    add_in_last();
    printf(".............\n");
    display();
    printf(".............\n");
    insert_at_first();
    printf(".............\n");
    display();
    printf(".............\n");
    printf("Enter position number to add a node: ");
    scanf("%d",&m);
    insert_in_nth( m);
    printf(".............\n");
    display();
    printf(".............\n");
    printf("Enter a position to delete: ");
    scanf("%d",&x);
    delete_by_pos(x);
    printf(".............\n");
    display();
    printf("Enter a value to delete: ");
    scanf("%d",&y);
    delete_by_valu(y);
    printf(".............\n");
    display();
    printf(".............\n");
    printf("Enter a position to search: ");
    scanf("%d",&z);
    search_by_pos(z);
    printf(".............\n");
    printf("Enter a value to search: ");
    scanf("%d",&h);
    search_by_valu(h);
    return 0;

}