Rearrange a given linked list in-place in Zig Zag

PROBLEM :

Given a singly linked list L0 -> L1 -> … -> Ln-1 -> Ln. Rearrange the nodes in the list so that the new formed list is : L0 -> Ln -> L1 -> Ln-1 -> L2 -> Ln-2.

Input:
You have to complete the method which takes 1 argument: the head of the  linked list. You should not read any input from stdin/console. There are multiple test cases. For each test case, this method will be called individually.

Output:
Your function should return a pointer to the rearranged list so obtained.

Constraints:
1 <=T<= 50
1 <= size of linked lists <= 100

Example:
Input:
2
4
1 2 3 4
5
1 2 3 4 5

Output:
1 4 2 3
1 5 2 4 3

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SIMPLE c++ IMPLEMENTATION :
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/*

The structure of linked list is the following

struct Node
{
int data;
Node* next;
};

*/
struct Node* reverse(struct Node *) ;


Node *inPlace(Node *root)
{
    if(root==NULL||root->next==NULL)
        return root ;
       
    Node *l1,*t1,*t2,*l2 ;
    t1=root ;
    t2=t1->next ;
    l1=root ;
    while(t2!=NULL&&t2->next!=NULL)
    {
        t1=t1->next ;
        t2=t2->next->next ;
    }
    l2=t1->next ;
    t1->next=NULL ;
   
    l2=reverse(l2) ;
   
    t1=l1;t2=l2 ;
   
   
    while(l1!=NULL&&l2!=NULL)
    {
        t1=l2->next ;
        l2->next=l1->next ;
        l1->next=l2 ;
        l1=l1->next->next ;
        l2=t1;
    }
   
    return root ;
   
   
}

struct Node* reverse(struct Node *head)
{
    if(head==NULL)
    return head ;
   
    if(head->next==NULL)
    return head;
   
    struct Node *one,*two,*third ;
    one=head ;
    two=one->next ;
    third=two->next ;
   
    one->next=NULL ;
    two->next=one ;
   
    while(third!=NULL)
    {
        one=two ;
        two=third ;
        third=third->next ;
       
        two->next=one ;
    }
    return two ;
}


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