Question

You are given a pointer to a singly linked list. The singly linked list has cycles due to a programming error.
Write a C program to detect whether the linked list has cycles without storing all the pointers to the
nodes. The function detect_cycles should return 1 when a cycle is found and 0 when there are no cycles.
Your code should handle all corner cases carefully and should not cause segmentation fault.
Figure shows various examples of cycles for a list with 3 nodes. The number of nodes in the input list
can range from 0 to a billion nodes.

struct node{
void* data;
struct node* next;
};
int detect_cycles(struct node* list){

Answer 1

//C program

#include<stdio.h>

struct node{
   void* data;
   struct node* next;
};

int detect_cycles(struct node* list){
   struct node *slow_ptr = list, *fast_ptr = list;
  
while (slow_ptr != NULL && fast_ptr != NULL && fast_ptr->next != NULL ) {
slow_ptr = slow_ptr->next;
fast_ptr = fast_ptr->next->next;
if (slow_ptr == fast_ptr) return 1;
}
return 0;

}