Deleting every Nth node from a linked lint - Implementaion Using C - Interview Question

                             Scenario

Consider  a game in which players are arranged circularly. The

game has to be played in a way demonstrared as follows.

1.) The games starts from first player as current player.

2.)A random number(n) from 1 to 10 is generated.

3.)  *The count goes from the current player and deletes the             

         Nth player…

      *After deleting the player, now the game starts from the player

         next to the  deleted player…

      *The game is to be stopped if there is only one player and the 

        player is  declared as a winner…

      (Design an algorithm for the game)

 #include<stdio.h>
#include<stdlib.h>
typedef struct Node
 {
    int data;
    struct Node *prev;
    struct Node *next;
 }Node;
Node *start=NULL;

void insert(Node *temp)
{
    Node *var,*last;
    Node *ptr=start;
  
    if(start==NULL)
    {
        temp->next=temp;
        temp->prev=temp;
        start=temp;
    }
    else
    {
      while(ptr->next!=start)
        {  
            ptr=ptr->next;
        }
         last=start->prev;
         ptr->next=temp;
         temp->prev=last;
         last->next=temp;
         temp->next=start;
         start->prev=temp;
    }
}

void display(Node *start)
{
  
    Node *ptr=start;
    if(start==NULL)
    printf("\n No elements present");
    else
    {
         printf("\n Elements in the Linked List are:");
        while(ptr->next!=start)
        {  
            printf("\n%d",ptr->data);      
            ptr=ptr->next;
        }
            printf("\n%d",ptr->data);  
    }
return;
}

int delete1(Node *start,int n)
{
    Node *t=start,*p,*q;
    int count;
    while(t->next!=t->next->next)  
    {       
        count=1;
        while(count<n)
        {  
            t=t->next;
            count++;
        }
        p=t->prev; q=t->next;
        p->next=q; q->prev=p;  
        free(t);
      
        t=q;  
    }
    return t->data;
}

Node *createNode(int data)
{
    Node *temp=(struct Node*)malloc(sizeof(struct Node));
    temp->data=data;
    return temp;  
}
int main()
{
    int data;
    Node *temp;

    temp=createNode(10);
    insert(temp);
      
    temp=createNode(20);
    insert(temp);  
  
    temp=createNode(30);
    insert(temp);  
  
    temp=createNode(40);
    insert(temp);  
  
    temp=createNode(50);
    insert(temp);  
  
    display(start);
  
    data=delete1(start,4);     /*Winner */
    printf("\n Winner is :: %d",data);  
    return 0;
}

 

 

O/P:  when N=4