Detect and Remove cycle in a single linked list
Write a C Program for Detect and Remove cycle in a single linked list. Here’s simple Program for Detect and Remove cycle in a single linked list in C Programming Language.
What is Linked List ?
Linked list is a linear data structure that contains sequence of elements such that each element links to its next element in the sequence. Each link contains a connection to another link.
Following are the important terms to understand the concept of Linked List.
- Link − Each link of a linked list can store a data called an element.
- Next − Each link of a linked list contains a link to the next link called Next.
Each element in a linked list is called as “Node”. Each node consists of its own data and the address of the next node and forms a chain. Linked Lists are used to create trees and graphs.
Below is the source code for C Program for Detect and Remove cycle in a single linked list which is successfully compiled and run on Windows System to produce desired output as shown below :
SOURCE CODE : :
/* C Program for Detect and Remove cycle in a single linked list */
#include<stdio.h>
#include<stdlib.h>
struct node
{
int info;
struct node *link;
};
struct node *create_list(struct node *start);
void display(struct node *start);
struct node *addatbeg(struct node *start,int data);
struct node *addatend(struct node *start,int data);
struct node *findCycle(struct node *start);
int lengthList(struct node *start, struct node *C);
int main()
{
struct node *start=NULL;
struct node *p,*psave=NULL, *prev, *ptr;
int len,i;
start=create_list(start);
if(start==NULL)
exit(1);
/*Insert a cycle at node containing 0*/
prev=p=start;
while(p!=NULL)
{
if(p->info==0)
psave=p;
prev=p;
p=p->link;
}
if(psave!=NULL)
prev->link=psave;
ptr = findCycle(start);
if(ptr==NULL)
printf("List is NULL terminated\n");
else
{
printf("\nThere is a cycle in the list\n");
len = lengthList(start, ptr);
printf("Length of the list is : %d\n",len);
ptr=start;
for(i=1;i<len;i++)
ptr=ptr->link;
ptr->link=NULL;
printf("Cycle Removed, now the list is NULL terminated\n");
}
display(start);
return 0;
}/*End of main()*/
/*Returns NULL if the list is NULL terminated otherwise returns the node where both pointers meet*/
struct node *findCycle(struct node *start)
{
struct node *slowP, *fastP;
if(start->link==NULL) /*only one element*/
return NULL;
slowP=fastP=start;
while(fastP!=NULL && fastP->link!=NULL)
{
slowP=slowP->link;
fastP=fastP->link->link;
if( slowP==fastP )
return slowP;
}
return NULL;
}/*End of findCycle()*/
int lengthList(struct node *start, struct node *C)
{
struct node *p1, *p2;
int len_Cycle, len_remainingList;
printf("Node at which the cycle was detected is %d\n",C->info);
p1=p2=C;
len_Cycle=0;
do
{
len_Cycle++;
p2=p2->link;
}while(p1!=p2);
printf("Length of cycle is : %d\n",len_Cycle);
len_remainingList=0;
p1=start;
while(p1!=p2)
{
len_remainingList++;
p1=p1->link;
p2=p2->link;
}
printf("Node that causes cycle is : %d\n",p1->info);
printf("Number of nodes not included in the cycle are : %d\n",len_remainingList);
return len_Cycle + len_remainingList;
}/*End of lengthList()*/
struct node *create_list(struct node *start)
{
int i,n,data;
printf("Enter the number of nodes : ");
scanf("%d",&n);
start=NULL;
if(n==0)
return start;
printf("\nEnter the element to be inserted : ");
scanf("%d",&data);
start=addatbeg(start,data);
for(i=2;i<=n;i++)
{
printf("\nEnter the element to be inserted : ");
scanf("%d",&data);
start=addatend(start,data);
}
return start;
}/*End of create_list()*/
void display(struct node *start)
{
struct node *p;
if(start==NULL)
{
printf("\nList is empty\n");
return;
}
p=start;
printf("\nList is :\n");
while(p!=NULL)
{
printf("%d ",p->info);
p=p->link;
}
printf("\n\n");
}/*End of display() */
struct node *addatbeg(struct node *start,int data)
{
struct node *tmp;
tmp=(struct node *)malloc(sizeof(struct node));
tmp->info=data;
tmp->link=start;
start=tmp;
return start;
}/*End of addatbeg()*/
struct node *addatend(struct node *start,int data)
{
struct node *p,*tmp;
tmp=(struct node *)malloc(sizeof(struct node));
tmp->info=data;
p=start;
while(p->link!=NULL)
p=p->link;
p->link=tmp;
tmp->link=NULL;
return start;
}/*End of addatend()*/
OUTPUT : :
/* C Program for Detect and Remove cycle in a single linked list */ ************** OUTPUT **************** Enter the number of nodes : 6 Enter the element to be inserted : 1 Enter the element to be inserted : 2 Enter the element to be inserted : 3 Enter the element to be inserted : 0 Enter the element to be inserted : 4 Enter the element to be inserted : 5 There is a cycle in the list Node at which the cycle was detected is 0 Length of cycle is : 3 Node that causes cycle is : 0 Number of nodes not included in the cycle are : 3 Length of the list is : 6 Cycle Removed, now the list is NULL terminated List is : 1 2 3 0 4 5
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