SCHOOL OF CODE BUILDERS: Linked List Implementation(detect a loop in a linked list)

Linked List Implementation(detect a loop in a linked list)

#include <stdio.h>
#include <stdlib.h>
struct node
{
 int data;
 struct node *next;
};

struct node* newnode(int data)
{
 struct node *new=(struct node*)malloc(sizeof(struct node));
 new->data=data;
 new->next=NULL;
 return new;
}

void insertastail(struct node **head,int data)
{
 struct node *temp;
 struct node *current=*head;
 if(current==NULL)
 {
  *head=newnode(data);
 }
 else
 {
  temp=newnode(data);
  while(current->next!=NULL)
   current=current->next;
  current->next=temp;
 }
}

void printlist(struct node *head)
{
 struct node *current=head;
 while(current!=NULL)
 {
  printf("%d ",current->data);
  current=current->next;
 }
}

int detectloop(struct node *head)
{
 struct node *slow=head;
 struct node *fast=head;
 while(fast!=NULL && fast->next!=NULL)
 {
  slow=slow->next;
  fast=fast->next->next;
  if(slow==fast)
   return 1;
 }
 return 0;
}

int main(void) {
 struct node *head=NULL;
 struct node *current;
 int data,size;
 int i,n;
 scanf("%d",&size);
 for(i=0;i<size;i++)
 {
  scanf("%d",&data);
  insertastail(&head,data);
 }
 printlist(head);
 printf("\n");
 //Uncomment the following block to enable the loop
 /*
 current=head;
 while(current->next!=NULL)
 {
  current=current->next;
 }
 current->next=head->next->next;*/
 if(detectloop(head))
  printf("loop detected");
 else
  printf("loop not detected");
 return 0;
}

Pages

Linked List Implementation(detect a loop in a linked list)