text: #include<bits/stdc++.h>
  using namespace std;
  struct node{
    int data;
    node *next;
    node(val){
      data = val;
      next = NULL;
    }
  };
  bool isCycle(node *head){
    //1 -> 2 -> 3 -> 4 -> 5 return 3
    //11 -> 12 -> 13 -> 14 return 12
    if(!head)
      return false
    node *fast = head, *slow = head;
    while(1){
      fast = fast -> next;
      if(!fast)
        break;
      fast = fast->next;
      if(!fast)
        break;
      slow = slow->next;
      
      if(fast == slow)
        return true;
    }
    return false;
  }
  
  int main(){
    //call here
  }
  