Detect Loop in linked list

PROBLEM :

Given a linked list, check if the the linked list has a loop. Linked list can contain self loop.

Input:

In this problem, method takes one argument: the head of the linked list. The function should not read any input from stdin/console.
The node structure has a data part which stores the data and a next pointer which points to the next element of the linked list.
There are multiple test cases. For each test case, this method will be called individually.

Output:

Return 1 if linked list has a loop else 0.

Constraints:

1<=T<=50
1<=N<=300

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SIMPLE c++ IMPLEMENTATION :
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/*
Detect a cycle in a linked list. Note that the head pointer may be 'NULL' if the list is empty.

A Node is defined as:
    struct Node {
        int data;
        struct Node* next;
    }
*/

bool has_cycle(struct Node* head) {
 
    struct Node *one,*two ;
    if(head==NULL||head->next==NULL)
        return 0 ;
 
    one=head ;
    two=head ;
 
    while((one!=NULL)&&(two!=NULL)&&(two->next!=NULL))
        {
        one=one->next ;
        two=two->next->next ;
     
         if(one==two)
         {
             return 1 ;
         }
    }
    return 0 ;
}


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